Sistem Reproduksi
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Sistem Reproduksi
- 1. REPRODUKSI
- 2. Organ reproduksi pria/jantan Fungsi : • Penis :Urinasi dan kopulasi • Uretra :Transport urin dan semen • Skrotum : Menjaga temperatur testis kira2 30 C dibawah suhu normal tubuh • Testis :Produksi sperma dan testoteron
- 3. • Epididmis : Storage and maturation • Uretra: Transport sperma ke uretra • Vesikel seminalis: Produksi alkalin semen (temasuk fruktosa) utk menyediakan energi utk sperma
- 4. Function: Produce Sperm Seminiferous Tubules Testis
- 5. Testis Cross Section Interstitial Cells Produce Testosterone
- 6. • Prostat :Produksi 1/3 dari semen termasuk nutrien dan enzim utk mengaktifkan sperma • Cowper Gland :sekresi mukus dan bufer alkalin untuk sekresi mukus dan buffer alkalin utk menetralisir kondisi asam uretra.
- 7. Organ reproduksi wanita/betina • Vagina : menerima penis dan semen serta saluran kelahiran dan menstruasi • Uterus: jalur lintas sperma, menerima blastocyst, fetus dan melindungi fetus dari suhu yg tdk sesuai
- 8. • Servix :sekresi mukus utk blocking saluran servik yg ke uterus • Endometrium: lapisan uterus utk implantasi • Miometrium : lapisan uterus utk kontraksi uterus
- 9. . • Tuba fallopi: jalur lintas oocyt dan tempat fertilisasi • Ovarium :produksi oocyt, estrogen dan testoteron • Fimbriae : menangkap oocyt
- 10. Hormon reproduksi • Gonadotropin-releasing Hormone (GnRH) : – sumber: Hypothalamus – Target & Fungsi: • Females & Males - Anterior Pituitary – Stimulasi produksi Follicle Stimulating Hormone (FSH) & Leutinizing Hormone (LH) – Mengatur pelepasan FSH & LH oleh anterior pituitary gland
- 11. Hormon reproduksi • Follicle Stimulating Hormone FSH): – Source: Anterior Pituitary – Targets & Functions: • Females - Ovaries – Stimulasi perkembangan folikel – Stimulasi produksi estrogen • Males - Seminiferous Tubules – Berperanan utk spermatogenesis dgn menstabilkan reseptor testosteron pada tubulus
- 12. Leutenizing Hormone (LH): • Source: Anterior Pituitary – Targets & Functions: • Females - Ovaries – Stimuli oosit primer menjadi oosit sekunder – Memacu ovulasi oosit sekunder – Transform folikel jadi korpus luteum – Stimulasi produsi progesteron oleh corpus luteum • Males - Seminiferous Tubules Corpus luteum – Stimulasi produksi (Spermatogenesis) melalui rangsangan interstitial cells dalam testes utk sekresi testosteron
- 13. Estrogen: • Sources: Pematangan Follicles & Corpus Luteum – Targets & Functions: • Tubuh secara umum – Stimulasi perkembangan organ reproduksi sekunder • Uterus – Stimulasi fase proliferasi siklus estrus • Ovarium – oogenesis • kelenjar mammae – Stimulasi perkembangan duktus kelenjar susu
- 14. Progesteron: • Source: Corpus Luteum & Placenta – Targets & Functions: • Females - Uterus – Penebalan endometrium – Stimulasi pelepasan nutrient – Quiets myometrium • Females – kelenjar susu Corpus luteum – Stimulasi perkembangan alveoli utk produksiair susu • Females - Anterior Pituitary – Menghambat produksi dan pelepasan FSH & LH
- 15. Testosterone: • Sources: Interstitial Cells in Testes – Targets & Functions: • Tubuh secara umumBody in general – Stimulasi perkembangan organ reproduksi jantan meliputi: » development of male genitalia » male skeleton and muscle development » male patterns for hair growth » increased RBC production & higher metabolic rate • Seminiferous tubules – spermatogenesis • Anterior Pituitary – Moderate inhibition of pituitary and hypothalamus
- 16. Oxytocin: • Sources: diproduksi oleh hypothalamus. Disimpan & dilepaskan oleh Posterior Pituitary Positive Feedback Mechanisms: 1. Childbirth – kontraksi uterus and serviks 2. Milk letdown reflex – Targets & Functions: • Uterus – Stimulasi kontraksi miometrium • Kelenjar susu – Stimulasi kontraksi duktus kelenjar susu untuk pelepasan air susu
- 17. Prolactin: • Source: Anterior Pituitary – Targets & Functions: • Breasts – Stimulasi alveoli utk produksi air susu • Regulation – Release of prolactin by anterior pituitary is regulated by hypothalamus production of Prolactin Releasing Hormone (PRH) & Prolactin Inhibiting Hormone (PIH)
- 18. Human Chorionic Gonadotropin (HCG): • Source: Trophoblasts of blastocyst & Chorion – Target & Functions: • Corpus Luteum – Memelihara corpus luteum & menyebabkan produksi progesterone tetap ada pada 4 bulan pertama kehamilan sampai plasenta menghasilkan estrogen dan progesteron dalam jumlah cukup utk memelihara kehamilan.
- 19. Pengaturan hormon ovarium dan siklus menstruasi 1. Hypothalamus melepaskan GnRH. 2. GnRH stimulasi anterior pituitary utk melepaskan FSH. Estrogen FSH 3. FSH stimulasi pertumbuhan folikel dan estrogen.
- 20. Hormonal Regulation of Menstrual & Ovarian Cycles LH 4. Peningkatan kadar Estrogen estrogen menyebabkan Estrogen FSH anterior pituitary produksi LH.
- 21. Hormonal Regulation of Menstrual & Ovarian Cycles 5. estrogen yang tinggi menyebabkan LH dilepas untuk ovulasi dan penebalan Estrogen endometrium (proliferative Estrogen phase). FSH 6. LH stimulasi pembelahan LH meiotik pertama oosit primer
- 22. Hormonal Regulation of Menstrual & Ovarian Cycles 7. LH yg tinggi memacu ovulasi. Estrogen Estrogen 8. LH yg tinggi FSH menyebabkan folikel LH ruptur menjadi corpus luteum.
- 23. Hormonal Regulation of Menstrual & Ovarian Cycles 9. Corpus luteum produksi progesteron Estrogen 10. Progesteron Estrogen Progesterone menghambat produksi X FSH FSH& LH oleh anterior X LH pituitary & stimulasi secretory phase .
- 24. Hormonal Regulation of Ovarian & Menstrual Cycles 11. Pengurangan kadar FSH & LH menyebabkan corpus luteum tdk berkembang dan produksi progesteron sedikit. 12. Pengurangan kadar X Estrogen estrogen & progesteron menyebabkan FSH X Progesterone penghambatan FSH & LH LH dan endometrium yang menebal akan ruptur X (menses).
- 25. Hormonal Regulation of Ovarian & Menstrual Cycles 13. Peningkatan kadar FSH menyebabkan siklus FSH estrus akan dimulai lagi
- 26. Definitions & Functions Relative to Reproduction • Fertilization: – Proses dimana gamet jantan dan betina fusi membentuk zygote diploid. • Polar Bodies: – Sel haploid nonfungsional female yg mempunyai sedikit sitoplasma yg diproduksi pd saat meiosis.
- 27. Gametogenesis: Proses pembentukan gamet • Spermatogenesis: • Oogenesis: – Produksi gamet – Produksi gamet jantan betina (oocytes) – Terjadi pd tubulus – Terjadi pada ovarium seminiferus testis – Pembelahan meisosis – pembelahan meiosis – Terjadi setelah – Terjadi stlh individu pubertas sampai mengalami pubertas menopause – Produksi – Secara normal piap 400.000.000per day siklus estrus.
- 28. Spermatogenesis Spermatogonium (46) Daughter Cells (46) Mitosis
- 29. Spermatogenesis Spermatogonium (46) Daughter Cells (46) Mitosis Growth Primary Spermatocyte (46) Meiosis I Secondary Spermatocytes (23)
- 30. Spermatogenesis Spermatogonium (46) Daughter Cells (46) Mitosis Growth Primary Spermatocyte (46) Meiosis I Secondary Spermatocytes (23) Meiosis II Early Spermatids (23)
- 31. Spermatogenesis Spermatogonium (46) Daughter Cells (46) Mitosis Growth Primary Spermatocyte (46) Meiosis I Secondary Spermatocytes (23) Meiosis II Early Spermatids (23) Spermiogenesis Late Spermatids (23)
- 32. Spermatogenesis Spermatogonium (46) Daughter Cells (46) Mitosis Growth Primary Spermatocyte (46) Meiosis I Secondary Spermatocytes (23) Meiosis II Early Spermatids (23) Spermiogenesis Late Spermatids (23) (Lumen) Spermatozoa (23)
- 33. Oogenesis Oogonium (46) (Mitosis) Primary Oocyte (46) Primary Oocyte (46)
- 34. Oogenesis Oogonium (46) (Mitosis) Primary Oocyte (46) (Meiosis 1) Polar Body (23) Secondary Oocyte (23) Fertilization Ovulation (Meiosis 2)
- 36. Hormonal Regulation if Pregnancy Occurs Blastocyst produksi human Chorionic Gonadotropin (hCG) hormon yg akan memelihara corpus luteum pada trimester pertama. hCG placenta akan memproduksi estrogen & progesteron utk kelangsungan hidup janin.
- 37. Definitions & Functions Relative to Reproduction • Semen: – Campuran dr semen dan cairan dr glandula reproduksi jantan utk mensupply energi, mentralkan kondisi asam pada pd alat reproduksi dan mengaktifkan sperma. • Hyaluronidase: – Enzym pd acrosome menyebabkan nukleus sperma mampu menembus gamet betina
- 38. Definitions & Functions • Zygote: – Hasil fertilisasi, diploid. • Cleavage Divisions: – Pembelahan mitotik dari zigot (preembrio) (2 cell, 4 cell, 8 cell, etc.) • Morula: – preembryonic cells berbentuk spt buah berry .
- 39. Zygote
- 41. Definitions & Functions • Blastocyst: – cairan yg mengisi rongga dr sel yg dibentuk pada morula yg implantasi ke endomterium • Inner Cell Mass: – Kmpulan dr sel yg berada di blastocyst. • Trophoblast: – Bagian dr dinding luar blastocyst yg akn membntuk chorion.
- 43. •implantas i
- 45. Definitions & Functions • Chorionic Villi: – Pertumbuhan sel trophoblast yg mirip spt jari ke endometrium mebntuk placenta.
- 46. Gastrulation • Preembryo menjadi embryo. Prembryo Embryo
- 47. Ectoderm Derivatives • Brain, spinal cord, nerves • Cornea & lens of eyes • Outer skin & accessory structures – hair – nails • Enamel of teeth • Linings of nasal & oral cavities & anal canal
- 48. Endoderm Derivatives • Epithelial lining of digestive tract • Liver and pancreas • Epithelial lining of respiratory tract & tonsils • Epithelial lining of reproductive ducts & glands • Thyroid, parathyroid & thymus glands • Epithelial lining of bladder & urethra
- 49. Mesoderm Derivatives • Muscle: skeletal, cardiac & smooth • Connective tissues: cartilage, bone, adipose • Bone marrow, blood & lymphatic tissues • Endothelial linings of blood & lymphatic vessels • Visceral peritoneum of organs in ventral cavity • Fibrous & vascular tunics of eyes • Organs of urogenital system: kidneys, gonads & reproductive ducts
- 50. Definitions & Functions • Chorion: – Membran embrionik paling luar yg akan mebntuk placenta & produksi human chorionic gonadotropin.
- 51. Definitions & Functions • Amnion: – Membran yg mengelilingi embryo utk membentuk cavum amniotik dan memproduksi cairan amnion.
- 52. Definitions & Functions • Amnionic Fluid: – Melindungi fetus dari trauma &fetus dapat bergerak bebas tanpa terjadi adesi
- 53. Definitions & Functions • Yolk Sack: – Menyediakan nutrisi dan supply sel darah merah.
- 54. Placental Function O Minerals Glucose Vitamins 2
- 55. Placental Function Alcohol
- 56. Placental Function Urea Wastes CO2
- 57. Preembryonic Development Bone Formation
- 58. Smoking During Pregnancy • Increases risk of ectopic pregnancy • Doubles risk of placenta previa & abruptio placenta • Slows fetal development • Doubles risk of low birthweight babies • Increases risk of preterm deliveries • Increases risk of cleft palate & lip • Doubles risk of sudden infant death syndrome (SIDS)
- 59. Placental Function - Smoking CO CO2 O2 Nicotine
- 60. Fetal Alcohol Syndrome • Gangguan pertumbuhan prenatal & postnatal (retardasi) • CNS (central nervous system) – Gangguan neurologis – Perkembangan terhambat • Alcohol berhunbungan dg cacat lahir • Mental retardation • Gangguan bicara dan mendengar • Learning, attention & memory deficits
- 61. Drug Use Antibiotics Nicotine Crack
- 62. Irradiation • High-energy – X-rays – Gamma rays dpt menyebabkan mutasi gen.
- 63. Placenta previa • Placental yg tumbuh sepanjang atau berdekatan dengan servix uterus. • Symptoms: – Spotting during 1st & 2nd trimesters – Sudden, painless & profuse vaginal bleeding
- 64. Ectopic Pregnancy • Implantasi blastocyst diluar uterus • Causes & Risk Factors: – Physical blockage of uterine tube. – Scarring of uterine tube by prior tubal infection (pelvic inflamatory disease). – Pregnancy following tubal ligation reversal or despite oral contraceptive use. • Symptoms: – Lower abdominal or pelvic pain. – Mild cramping on one side of pelvis. – Abnormal vaginal bleeding (spotting).
- 65. Syphilis • Bacterial Pathogen: Treponema pallidum • Transmission: Sexual & transplacental contact.
- 66. • Mitosis dan meiosis • Pelajari!
- 67. • Mitosis: – Proses dimana nucleus of body cells membelah menjadi identical daughter cells utk maintenance, healing & growth. • Meiosis: – Proses dimana gamet dibentuk dari separo jumlah normal kromosom utk reproduksi seksual.
- 68. Mitosis Interphase Prophase Metaphase
- 69. Mitosis Anaphase Telophase Interphase 46 46 • sel dl tubuh : tmbuh, regenerasi, •Tidak ada perubahan jumlah kromosom dalam tiap sel
- 70. Meiosis 46 Interphase Prophase Metaphase
- 71. Meiosis 23 23 Reduction Division Anaphase Telophase Interphase
- 72. Meiosis 23 23 23 23 23 23 •Hanya pada sel kelamin. • Synapsis & shuffling of genetic information providing variation. • Results in reduction of number of chromosomes by half (haploid).
- 73. Mitosis/Meiosis Comparison 46 46 23 23 46 46 23 23 23 23
Notas do Editor
- As you go through the notes associated with each slide in this unit, right click the mouse or depress either the right arrow key or the down arrow key to advance the animation or the slide each time you see this symbol *. Depress the left arrow key or the up arrow to return to the previous slide or animation. *
- Each testis is filled with tiny tubules * * called seminiferous tubules. * It is within the seminiferous tubules that sperm are produced through the process of spermatogenesis which occurs from puberty on. *
- Shown here * is a cross section through a testis showing the seminiferous tubules. The white spaces * represent the central opening or lumen of each tubule. * In this more highly magnified view of seminiferous tubules, you can visualize the development of sperm cells in the walls of the seminiferous tubules. * By the time the sperm cells are fully developed, they are located in the lumen of the tubule. * Between the seminiferous tubules are groups of cells called interstitial cells. * * These are responsible for the production of the male hormone testosterone within the testes. * *
- The vagina * * serves as the birth canal during the delivery of an infant, a passageway for menstrual flow and as the female organ of copulation which receives the penis and semen during sexual intercourse. * *
- The uterine tubes are also know as the oviducts and the fallopian tubes. * * Their function is to receive the oocyte following ovulation, provide a passageway for the oocyte to be transported to the uterus by means of peristalsis and ciliary action, and serve as an area in which fertilization of the oocyte can occur. * *
- Gonadotropin-releasing Hormone (GnRH) * is produced by the hypothalamus. * * It’s target in both males and females is the anterior pituitary gland. * * which it stimulates to produce FSH and LH. * The Hypothalamus also regulates the release of FSH and LH by the anterior pituitary.* *
- Follicle stimulating hormone (FSH) * is produced by the anterior pituitary gland. * * It’s target in females * is the ovaries * in which it stimulates the growth and maturation of a follicle * and causes the maturing follicle to produce the hormone estrogen . * The target of FSH in males is the seminiferous tubules. * The effect of FHS is to cause the development of testosterone receptors on the seminiferous tubules, promoting sperm production. * *
- Leutenizing hormone (LH) * is produced by the anterior pituitary gland. * * It’s targets in the female are the ovaries. * The effect of LH within the ovaries is to stimulate a primary oocyte * to complete its first meiotic division to become a secondary oocyte. * It triggers ovulation (release) of the secondary oocyte, * the transformation of the ruptured follicle into a corpus luteum * and stimulates the production and release of the hormone progesterone from the corpus luteum. In Males, * the target of LH is the interstitial cells between the seminiferous tubules of the testes. Under the influence of LH, the interstitial cells produce and release testosterone * which binds to the receptors on the seminiferous tubules making possible sperm production (spermatogenesis). *
- Estrogen is the principle female hormone. * It is produced by maturing follicles and by the corpus luteum within the ovaries. * Estrogen has a number of targets and functions within the body. * In general, estrogen stimulates the development of female secondary sexual characteristics * which are those that distinguish females from males. These would include the development of female genital organs, breasts, bone development and growth patterns typical of females, etc. * During the uterine cycle, estrogen stimulates the proliferative phase which causes the thickening and growth of the endometrium in preparation for possible implantation of a blastocyst. * Within the ovaries, estrogen promotes oogenesis within a developing and maturing follicle. * It stimulates the development of milk ducts and sinuses (ampullae) within the breasts in preparation for milk production. * Estrogen also has an effect on the anterior part of the pituitary gland in that as estrogen levels in the blood rise to a certain level, it stimulates a burst-like release of the hormone LH from the anterior pituitary. *
- Progesterone * is produced initially by the corpus luteum. * If pregnancy occurs, progesterone is also produced by the placenta as well. * It also has several targets and functions within the body. * One of the target organs of progesterone is the uterus. It maintains the thickened condition of the endometrium, stimulates nutrient release from the blood vessels in the walls of the uterus, and decreases muscular contractions of the myometrium. * Progesterone also affects the breasts by stimulating the development of the milk producing glands (alveoli). * Progesterone has the effect on the anterior pituitary gland of inhibiting the production and release of both FSH and LH. *
- Testosterone is the male sex hormone. * As indicated previously, it is produced by the intersitital cells in the testes. * Like estrogen in females, testosterone in males has a number of targets and functions. It has a generalized effect on the body to stimulate the development of male secondary sexual characteristics including the development of male genital organs, stimulating male type skeleton and muscle development, male patterns for hair growth, increased red blood cell production and a higher rate of metabolism to name a few. * The seminiferous tubules of the testes also are targets for testosterone. When testosterone binds with receptors on the seminiferous tubules, the process of spermatogenesis may be completed. * The anterior pituitary gland also is affected by testosterone in the blood. It’s effect is to cause moderate inhibition of the pituitary and the hypothalamus. *
- The hormone onytocin is manufactured by the hypothalamus and is stored by the posterior pituitary. * It is involved in positive feedback mechanisms * including childbirth * and the milk letdown reflex. * The contractions associated with childbirth are triggered by stretching of the cervix and the uterus as term is reached. * Increasing amounts of oxytocin in the blood triggers the myometrium of the uterus to contract causing the lowering of the fetus and labor. * The suckling effect on the breast of a nursing baby * stimulates the release of oxytocin which when bound to the tissues of the milk ducts and sinuses of the breasts, stimulates the release of milk. *
- Prolactin is a hormone stored by the anterior pituitary. * It’s targets * are the alveoli of the breasts, which it stimulates to produce milk. The release of prolactin is regulated by the hypothalamus. * *
- Human Chorionic Gonadotropin (hCG) is a hormone that is initially produced and secreted by the trophoblast cells of the blastocyst and later the chorion. * It’s target is the corpus luteum, * which it maintains in the absence of LH. * The effect of hCG on the corpus luteum * is to cause it to continue the production of progesterone during the first four months of pregnancy. By that time, the placenta is producing sufficient estrogen and progesterone to maintain the pregnancy. *
- The ovarian cycle begins when rising levels of GnRH from the hypothalamus * * stimulate increased production and release of Follicle Stimulating Hormone (FSH) by the anterior pituitary. * * FSH stimulates one or more follicle cells within the ovaries to grow * * and begin producing estrogen. * *
- Rising estrogen levels in the blood * * inhibits further release of FHS while promoting increased production and storage of the hormone Leutinizing Hormone (LH) * within the anterior pituitary gland. *
- When estrogen levels in the blood become high enough, * * LH is released by the anterior pituitary gland in a burst. The high estrogen levels also cause the endometrium to thicken. * The sudden release of LH into the blood,* causes the primary oocyte in the mature follicle to undergo the first meiotic division. * *
- The high LH levels * also cause the mature follicle to release the primary oocyte (ovulation), * and the remains of the ruptured follicle * to become a corpus luteum. * *
- The corpus luteum * * begins to produce and release the hormone progesterone * which inhibits the production of FHS and LH by the anterior pituitary * and stimulates the secretory phase of the ovarian cycle. *
- * Diminishing levels of FSH & LH cause the corpus luteum to deteriorate & produce less progesterone. * * * Diminishing levels of estrogen and progesterone * stop the inhibition of FSH & LH by the pituitary gland. * In the absence of adequate levels of progesterone, the thickened endometrium sloughs, causing menses to occur. *
- * Increasing levels of FSH * cause a new cycle to begin. *
- A spermatozoan * is a male gamete which has completed meiosis 1 and 2, spermiogenesis and is capable of fertilizing a female secondary oocyte. * Fertilization * is the process through which haploid male and female gametes combine to form a single cell (zygote) which has 46 chromosomes. * A human cell with 46 chromosomes (23 from the spermatozoan and 23 from the ovum) is said to be diploid. * Polar bodies * are haploid female cells with an insufficient amount of cytoplasm to be functional for reproductive purposes. * One polar body is produced during the first meiotic division while two additional polarbodies are procuced during the second meiotic division. *
- Gametogenesis * is the process through which male and female gametes are formed. * Spermatogenesis is the process through which male sperm are produced. * As indicated previously, spermatogenesis occurs in the seminiferous tubules of the testes. * It involves the process of meiosis through which the number of chromosomes is reduced by half ( from 46 to 23 ). * This process occurs throughout the life of a healthy male after puberty. * As many as 400,000,000 sperm may be produced a day through this process. * * Oogenesis * is the process through which the female gamete (oocyte) is produced. * As previously discussed, oogenesis takes place in a developing follicle within the ovaries. * It also involves meiosis, in which the number of chromosomes within the oocyte changes from 46 to 23. * Oogenesis takes place as a part of the ovarian cycle from puberty until menopause. * In humans, a single oocyte is typically produced during each ovarian cycle. * *
- Spermatogenesis takes place in the walls of the seminiferous tubules within the testes. Each of the cells forming the outermost layer of cells in the seminiferous tubules * is called a spermatogonum * and has 46 chromosomes. These cells divide by mitosis * * to form identical daughter cells * with 46 chromosomes. *
- Daughter cells go through a growth process * and are referred to as primary spermatocytes * which still have 46 chromosomes. Under the influence of the male hormone testosterone, primary spermatocytes go through the first meiotic division * in which the number of chromosomes is reduced from 46 to 23. * The cells (containing only 23 chromosomes) which are produced through this first meiotic division are referred to as secondary spermatocytes. * *
- The secondary spermatocytes produced by through the first meiotic division go through a second meiotic division * in which there is no change in the number of chromosomes (23). * The cells produced through the second meiotic division are referred to as spermatids. * Note that from a single primary spermatocyte * which goes through meiotic divisions I and II, * four spermatids are formed. * *
- The early spermatids * then go through a process called spermiogenesis * in which they change in shape and form to become late spermatids * with a flagellum * and other specialized organelles necessary for them to function as male gametes. *
- The spermatids * are released into the lumen of the tubule * along which they travel to the epididymis where they complete their development into mature spermatozoa * and are stored. * Note that this entire process of spermatogenesis occurs continually in the walls of the seminiferous tubules after puberty. *
- The process of female gamete production is called oogenesis. Oogenesis starts in the ovaries during fetal development, * when the female oogonia (which have 46 chromosomes), * divide by mitosis, * go through a growth phase, and are surrounded by follicle cells to become primordial follicles. The growing oogonium inside each primordial follicle is called a primary oocyte and continues to have 46 chromosomes. * Although the primary oocytes within the primordial follicles begin meiosis, they become stalled toward the end of prophase I. When a female baby is born, she has within her ovaries all of the primordial follicles she will ever have, * and they are all arrested in prophase I of meiosis. These will remain in this state of suspended animation * during childhood * until puberty. While a small number of follicles are activated each month after puberty, under the influence of FSH, only one follicle is selected to develop. *
- When LH is released in a burst, the primary oocyte within the dominant follicle completes the first meiotic division * to produce a secondary oocyte with 23 chromosomes * and a nonfunctional polar body. * The polar body is non-functional because the secondary oocyte retains almost all of the cytoplasm from the primary oocyte cell. * Under the influence of LH, the secondary oocyte is ovulated (released) from the follicle. * As the secondary oocyte travels down the oviduct, if it encounters sperm and is fertilized * * the penetration of the secondary oocyte by the sperm cell * triggers a second meiotic division, * resulting in the development of an ovum and three non-functional polar bodies from the original primary oocyte. *
- However, the blastocyst * (developing embryo) * produces the hormone human Chorionic Gonadotropin (hCG) * * maintains the corpus luteum * in the absence of FSH & LH for the first trimester of the pregnancy. * Eventually the placenta produces sufficient estrogen and progesterone to sustain the pregnancy. *
- A hormone * is a chemical messenger used to regulate reproductibve cycles and activities by binding with receptors on or in target cells. * Semen * is a mixture of spermatozoa and fluid secretions from male reproductive glands which supplies energy to spermatozoa, neutralizes acidic conditions within the male and female reproductive tracts and activates the spermatozoa. * Hyaluronidase * is an enzyme within the acrosome of a sperm cell that enables the sperm nucleus to enter the female ovum. *
- Objective 11 A zygote * is a fertilized ovum which is diploid due to the combination of the sperm and ovum nuclei. * Cleavage divisions * refer to divisions of the zygote to increase the number and surface area of cells making up the preembryo (ie, 2 cell stage, 4 cell, 8 cell, etc.). * A morula * is a berry shaped cluster of preembryonic cells produced from the cleavage divisions. * *
- Objective 11 A blastocyst * is a hollow, fluid filled sphere of cells formed from the morlula. * The blastocyst implants in the thickened uterine wall, the endometrium. * The inner cell mass * is the mass of cells inside the blastocyst * from which the three primary germ layers develop. * A trophoblast * is the name of the single layer of cells making up the outer wall of the blastocyst. * The trophoblast cells, eventually form the chorion. * *
- Objective 11 The chorionic villi * are the finger-like extensions of the trophoblasts * which grow into the endometrium * to acquire nutrients for the preembryo. * The chorionic villi eventually form the placenta. *
- Objective 11 Gastrulation * is the process through which the preembryo * becomes an embryo * as the three primary germ layers; * the ectoderm * the endoderm * and the mesoderm * develop to allow for the beginning of organ development. *
- Objective 10 The primary germ layer called the ectoderm * produces the brain, spinal cord and nerves; * the cornea and lens of the eyes; * the outer skin and accessory structures * including the hair * and nails; * the enamel of teeth * and the linings of the nasal and oral canals. * *
- Objective 10 The endoderm * is the source of the epithelial linings of the digestive tract; * the liver and pancreas; * the tonsils and the epithelial linings of the respiratory tract; * the epithelial linings of the reproductive ducts and glands; * the thyroid, parathyroid and thymus glands, * and the epithelial linings of the bladder and urethra. * *
- Objective 10 The mesoderm * produces all types of muscle tissue; * connective tissues, including cartilage, bone and adipose; * bone marrow, blood and lymphatic tissues; * the endothelial linings of blood and lymphatic vessels; the visceral peritoneum of visceral organs; * the fibrous and vascular tunics of the eyes; * and the organs of the urogenital system, including the kidneys, gonads and reproductive ducts. * *
- Objective 11 The chorion * is the outermost embryonic membrane * which protects the developing embryo. * The Chorion eventually produces the placenta which provides for the exchange of nutrients and wastes between the mother and the embryo. * *
- Objective 11 The amnion * is the membrane * which surrounds the embryo to form the amniotic cavity. * The amnion produces amniotic fluid which bathes the embryo to protect it. * *
- Objective 11 The amniotic fluid * bathes the embryo/fetus * protecting it from trauma * and permitting free movement without adhesions. * *
- Objective 11 The yolk sack * provides initial nutrients while the placenta is developing, * supplies the first RBC’s * and seeds the gonads with primordial germ cells.* *
- Objective 12 The function of the placenta is to provide for the exchange of nutrients from the maternal blood into the fetal blood, without direct mixing of the two. Nutrients move by simple diffusion from areas of higher concentration of each nutrient into the area of lower concentration. Thus O 2 diffuses from the mother’s blood into the blood of the fetus. * The same is true of glucose,* vitamins *, minerals *, etc. *
- Objective 12 If the mother carrying the fetus consumes alcohol, * it too diffuses across the placenta from the maternal blood into the fetal blood. The abuse of other drugs and even the use of legally prescribed antibiotics can have an adverse effect on the fetus.*
- In addition to supplying nutrients, the placenta also provides a mechanism for the disposal of wastes from the fetus. * Since CO 2 is a metabolic waste and the fetal lungs are not working, concentrations of CO 2 in fetal blood are higher than in the maternal blood. * As a result, excess CO 2 diffuses across the placenta into the maternal blood to be carried off and disposed of. * The same is true of other wastes * including urea. * *
- Objective 9 Preembryonic development * occurs from fertilization of the ovum till the third week of development. * From the third week after fertilization through the eighth week of development, * the conceptus is referred to as an embryo . The conceptus is referred to as an fetus * from the 9th week through birth. * The main event that separates embryonic and fetal development, is the beginning of bone formation * which begins during the ninth week. *
- For reasons not completely understood, research data indicates that smoking during pregnancy * increases the risk of ectopic pregnancy, * doubles the risk of placenta previa and extopic pregnancy, * slows fetal development, * doubles the risk of low birthweight babies, * increases the risk of cleft palate and lip, and * doubles the risk of sudden infant death syndrome (SIDS).
- Cigarette smoke contains more than 2,500 chemicals, not the least of which are carbon monoxide (CO) and nicotine. * Because CO has such a high affinity for hemoglobin, * its effect on RBCs is to reduce the amount of O 2 in the mother’s blood and therefore the amount of O 2 available to the fetus. Because smoking introduces a higher concentration of CO 2 into the lungs, it also effects the CO 2 gradient, thus reducing the amount of CO 2 which diffuses from fetal blood across the placenta in to the maternal blood for elimination. * Smoking also subjects the fetus to the carcinogen nicotine. * *
- Objective 12 Fetal alcohol syndrome * is used to describe a pattern of abnormalities found in children born to mothers who reported consuming moderate to large amounts of alcohol during pregnancy. Effects on the fetus vary widely but typically may include * prenatal and postnatal growth retardation; * Central Nervous System involvement including * neurological abnormalities, * developmental delays; * alcohol related birth defects including skull and facial malformations; * mental retardation; * speech and hearing impairment; * and learning, attention and memory deficits. * Although studies indicate a strong correlation between the seriousness of defects and quantities of alcohol consumed during pregnancy, it is not known whether there is a threshold below which alcohol may be consumed during pregnancy without harming the fetus. Therefore, clinicians generally recommend complete abstinance during pregnancy. *
- Just as nicotine can cross the placenta, * other drugs may do so as well. Even antibiotics * taken by the mother may cross the placenta and have an effect on the rapidly dividing cells of the growing fetus. * Of course hard core drug use may cause the fetus to become addicted along with the mother. *
- Irradiation * including high energy X -rays * and Gamma rays * may affect a fetus by penetrating deeply into fetal tissues, causing ionization of molecules, * may directly or indirectly affect the genetic material of cells, causing point mutations which affect a single base * or break chromosomes causing deletions or translocation of genetic information which may adversely affect fetal cells and tissues. *
- Placenta previa * is the medical term used to refer to growth of the placenta across or adjacent to the opening of the cervical canal of the uterus. * Risk factors include: * the number of prior pregnancies, * multiple pregnancies (including twins or triplets, etc.), * and a prior C-section where the scar is close to the cervix. * Symptoms associated with placenta previa may include * spotting during the 1st and 2nd trimesters, and * sudden, painless but profuse vaginal bleeding at any time during the pregnancy. *
- The term ectopic pregnancy * is used when the blastocyst implants anywhere other than within the uterus. * Common causes and risk factors for ectopic pregnancy include: * physical blockage of a uterine tube, * scarring of uterine tubes due to prior tubal infections such as venereal diseases causing pelvic inflamatory disease, * and pregnancies following tubal ligation reversal or despite oral contraceptive use. Symptoms associated with ectopic pregnancy include: * unexplained lower abdominal or pelvic pain, * mild cramping on one side of the pelvis * and abnormal vaginal bleeding or spotting. *
- Syphilis is a sexually transmitted disease (STD) * caused by the bacterial spirochete Treponema pallidum . * * It is acquired through sexual and transplacental contact with an infected person. Syphilis is the third most commonly reported microbial disease in the U.S.*
- Mitosis * is the process through which the nucleus of cells divide to produce two identical daughter cells, each having the same number of chromosomes as the original cell. * Mitosis is the process through which the body maintains grows, heals and maintains itself. * Meiosis * is the process through which gametes are formed with only half of the normal number of chromosomes (ie, in humans the number changes from 46 to 23). These haploid cells (with 23 chromosomes) develop into gametes for sexual reproduction. * Ovum * is the name of the functional female gamete which, as a result of sperm penetration, has completed the first and second meiotic divisions to become haploid. * *
- In the cell cycle, mitosis is when the nucleus divides. * Cells spend most of their time in interphase. * * This is when the cells has a definite nucleus, the chromosomes are spread out as chromatin and the cell is actively carrying out normal metabolic activities. Mitosis begins with prophase, * when the nuclear membrane disappears, the chromosomes condense and can be seen as discrete structures, and the centrioles move to opposite sides of the cell and send out spindle fibers which attach to each chromosome.* * The centrioles begin to retract the spindle fibers causing the chromosomes to line up on the equatorial plate of the cell. * When the chromosomes are aligned in this way, the cell is in metaphase. *
- As the spindle fibers continue to tug on the chromosomes, the two chromatids making up each chromosome are pulled apart and toward opposite sides of the cell. * Anaphase is the name of this stage when the chromatids from each chromosome are moving to opposite poles of the cell. * * When the chromatids reach the opposite sides of the cell, a nucleus reforms around each cluster, nucleoli reappear and cell membrane forms between the two nuclei to form two identical cells. The division of the cytoplasm is called cytokinesis. All of this occurs in what is called telophase. When the cell membrane completely separates the two daughter cells, telophase is complete * and the daughter cells are considered to be in interphase again. * * During interphase, the DNA making up the chromatids replicates so that each chromosome is composed of two identical chromatids. In mitosis, there is no change in the number of chromosomes or genetic information. If the cell dividing started out with 46 chromosomes, * the daughter cells will have 46 chromosomes. *
- Meiosis is a process that occurs in the gonads. In human cells, each cell undergoing meiosis begins with 46 chromosomes. * In prophase I of meiosis, * the same general things occur that happened during prophase of mitosis. * However, homologous chromosomes (one from each parent) pair up in a process called synapsis. * As the genetic information on the corresponding chromosomes from different parents will contain different genetic information, the synapsis and exchange of chromatid parts results in some shuffling and recombination of genetic information. * The spindle fibers from the centrioles attach to each chromosome pair, rather than to each chromosome. * The synapsed chromosome pairs become aligned on the equatorial plate of the cell in metaphase I of meiosis.* Thus the chromosome pairs in metaphase form a tetrad, a cluster of four chromatids. *
- In anaphase I of meiosis * the chromosomes forming each pair are pulled apart to opposite sides of the cell. * Telophase I is when the nuclear membrane forms around each cluster of chromosomes at each pole of the cell while cytokinesis occurs. * When cytokinesis complete, each of the daughter cells only contains half of the number of chromosomes that were present in the original cell. * In humans this number would be 23. * This is why the first meiotic division is referred to as the reduction division. *
- Meiosis is different from mitosis in that there is a second division of each of the daughter cells just like in mitosis. * The two daughter cells go through the same process as in a normal mitotic division, including prophase II, * metaphase II, * anaphase II, * and finally telophase II and cytokinesis. * There is no change in the chromosome number in the cells. * Thus, as the cells in prophase II have 23 chromosomes, the four daughter cells will contain 23 chromosomes. * * Meiosis is different from mitosis in that * it involved two divisions which only occur in the gonads after puberty, * as a result of the synapsis of homologous chromosomes and the exchange of genetic information that occurs, there is the possibility of greater variation within the daughter cells, * and the number of chromosomes within each of the four daughter cells that go through the process is reduced to half of the normal number * (in humans from 46 chromosomes to 23). *
- Contrasting mitosis and meiosis, in mitosis, * the chromosomes line up in metaphase as individual chromosomes. * There is no change in the number of chromosomes within each daughter cell produced through mitosis. * If the cell started out with 46 chromosomes, the daughter cells will be identical with 46 chromosomes. * In meiosis, * chromosomes synapse to form tetrads in prophase I. * As a result, the chromosomes line up in metaphase as tetrads or pairs of homologous chromosomes. * The daughter cells produced from the first meiotic division are haploid, * or contain only half of the number of chromosomes found in the original cell. * The four daughter cells produced in the second meiotic division are haploid, in that they only contain half of the number of chromosomes that were found in the original cell.* These haploid cells become gametes for sexual reproduction. * Since the chromosomes found in the daughter cells include a random distribution of chromosomes from each parent, each of the daughter cells contains genetic information that is unique. *