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 SEX CELL DIFFERENTIATION
 OOGENESIS – EGG DIFFERENTIATION
 SPERMATOGENESIS – SPERM DIFF.
◦ SPERMIOGENESIS – TRANSFORMA...
 IN MAN/MAMMALS, PRIMORDIAL GERM
CELL COMES FROM YOLK SAC ENTODERM
NEAR CAUDAL END OF BODY
 FROM THERE THEY MIGRATE FORW...
 PROLIFERATION IS PERIODIC (MONTHLY
IN FEMALES) URING THE POTENTIAL
CHILD-BEARING YEARS
 CELL PROLIFERATION – PRIMITIVE CELL
REPEATEDLY DIVIDES
 PERIOD OF GROWTH – RAPID
ENLARGEMENT OF THE CELLS PRODUCED
 PE...
 ORIGIN OF THE FOLLICLES
◦ PRIMORDIAL CELLS (OOGONIA)
PROLIFERATE WITHIN THE CORTEX OF
THE OVARY
◦ SMALLER EPITH. CELLS, ...
 370,000 – AT BIRTH
 190,000 – AT PUBERTY
 26,000 – AT AGE 30
 AFTER 30 OR MORE YEARS (CHILD-
BEARING SPAN), FOLLICLES...
 NO ADVANCE BEYOND THE STAGE OF
THE PRIMARY FOLLICLE UNTIL PUBERTY
(14TH YEAR)
 FEW HUNDREDS OF OOCYTES ARE
LIBERATED PE...
 GROWTH OF FOLLICLE STARTS SLOWLY
BUT GROWS RAPIDLY 1-3 DAYS PRIOR TO
RUPTURE
 MATURATION – ACHIEVED BY MEIOSIS
WITH 4 C...
 1 LARGE RIPE OVUM
 3 RUDIMENTARY OVA (POLAR BODIES) OR
POLOCYTES
 CYTOPLASM – GRANULAR AND
CONTAINS FEW TO MANY INERT
...
 YOLK – USEFUL IN CLASSIFYING EGGS.
I. BASED ON RELATIVE ABUNDANCE OF
YOLK:
1. SMALL
2. MEDIUM
3. LARGE
II. DISTRIBUTION OF YOLK IN CELLS:
1. ISOLECITHAL – EQUAL YOLK
MEIOLECITHAL – LITTLE YOLK
- INVERTEBRATES
- ALL MAMALS EXC...
-INVERTEBRATES
-ALL VERTEBRATES LOWER THAN
MARSUPIALS
- CHICK EGG
3. MEDIALECITHAL (MEDIUM YOLK) –
MODERATE YOLK – AMPHIBI...
5. CENTROLECITHAL- DISTINCTIVE
ARRANGEMENT OF YOLK, MASSED
CENTRALLY BUT SORROUNDED BY A
PERIPHERAL SHELL OF CLEAR
CYTOPLA...
- VIGOROUS PART IN DEVT. & WHERE
HIGHEST CAPACITY FOR ACTIVITY RESTS
- VEGETAL POLE- SLUGGISH END OF CELL
AND CONCERNED WI...
2° MEMBRANE- ZONA PELLUCIDA
3° MEMBRANE –ADDED BY THE OVIDUCT
AS THE EGG PASSES THROUGH IT
- JELLY OF FROG’S EGGS
- ALBUME...
CELLULAR CORDS ( GERMINAL
EPITHELIUM)
TESTES TUBULES
 SPERMATOGONIA (STEM CELLS)- LARGER
 INDIFFERENT CELLS- SMALLER
 ...
 DETACHED FROM SERTOLI CELLS AND ARE SET
FREE INSIDE THE SEMINIFEROUS TUBULES
 SPERM CELL- SMALLEST CELL IN MASS MADE
UP...
 CHROMOSOME NUMBERS
(2N) MAN=46 (DIPLOID CHROMOSOME#)
(N) MAN=23 (HAPLOID CHROMOSOME#)
 FEMALE
-22 ORDINARY CHROMOSOME P...
 24 DIFFERENT KINDS OF CHROMOSOMES
COMPARISON OF EGG & SPERM OF
ANIMALS IN GENERAL
FEATURES OVUM SPERMATO-
ZOON
SIZE LARGE SMALL
SHAPE SPHEROIDAL ELONGATED
QUANTITY FEW (ONE) OFTEN IN
MILLIONS
MOTILITY NON...
CYTOPLASM BULKY MINIMAL
YOLK LITTLE TO
MUCH
NONE
CENTRO-
SOME
DISAPPEARS RETAINED –
CENTRIOLE &
AXIAL
FILAMENT
MITOCHON-
D...
GOLGI-
APPARATUS
DIFFUSED IN
ACROSOME
ONLY
NUCLEUS OPEN
STRUCTURED
CONDENSED
AS SPERM
HEAD
NUCLEOLUS TYPICAL INDISTINGUIS
...
 INTERNAL FERTILIZATION
-SMALL NUMBER OF EGGS
 EXTERNAL FERTILIZATION
-LARGE VOLUME OF EGGS
TYPES OF BREEDING:
• CONTINU...
• PROVOKED OVULATION- INDUCED BY
THE ACT OF COPULATION.
• PERIODIC (INTERVALS OF 4 WEEKS)
SPONTANEOUS
 HUMAN FEMALE
-OVUL...
- HORMONAL FACTOR AND LOCAL
WEAKENING OF FOLLICULAR WALL
EGG TRANSPORT- MADE POSSIBLE BY
HORMONAL CONTROL AND OVARY
ACTIV...
 EGG VIABILITY- FERTILIZABLE PERIOD IS
LESS THAN ONE DAY – GENERATION
TAKES PLACE
CORPUS LUTEUM- OVARIAN STRUCTURE
(COLL...
• PSEUDOCOPULATION- INCREASES
CERTAINTY OF UNION
• COPULATION- SEXUAL EMBRACE
SPERM STORAGE- ACCUMULATION AT
EPIDIDYMIS(T...
• SEMINAL VESICLE
• BULBO-URETHRAL GLAND
• PROSTATE GLAND
 3 ML EJACULATE-250,000,000 SPERMS
SPERM TRANSPORT-LASHING,
FL...
 IN VITRO- TWO WEEKS
 HUMAN SEMEN(FROZEN IN GLYCEROL
 AT - 70℃ (CAN SURVIVE FOR MANY
MONTHS
 PROCESS WHEREBY 2 GAMETES FUSE
TOGETHER TO CREATE A NEW INDIVIDUAL
WITH A GENOME DERIVED FROM BOTH
PARENTS
 ACCOMPLISHE...
 1. CONTACT AND RECOGNITION BETWEEN
SPERM AND EGG. THIS ENSURES THAT THE
SPERM AND EGG ARE OF THE SAME SPECIES
 2. REGUL...
 3. FUSION OF THE GENETIC MATERIAL OF
SPERM AND EGG
 4. ACTIVATION OF EGG METABOLISM TO
START DEVELOPMENT
 ANTON VAN LEEUWENHOEK – CO-
DISCOVERER OF SPERM
 NICOLAS HARTSOEKER – CO-DISCOVERER OF
SPERM
 DREW A PICTURE OF A PREF...
 POOLING TOGETHER OF SPERM AND EGG
NUCLEI
• INVERTEBRATES ( ROTIFERS,
CRUSTACEANS INSECTS) DEVELOP
WITHOUT THE BENEFIT OF...
 RESULTS OF FERTILIZATON:
1. REASSOCIATION OF MALE AND FEMALE
SETS OF CHROMOSOMES , RESTORING
THEM TO THE FULL DIPLOID NU...
 SEX DETERMINATION – IS ESTABLISHED
AT THE TIME OF FERTILIZATION
 DURING MEIOSIS, CHROMOSOME NUMBER
IS HALVED
 22+X – F...
 PERIODS OF EARLY DEVELOPMENT:
1) GAMETOGENESIS
2) FERTILIZATION
3) CLEAVAGE
4) GASTRULATION
 FERTILIZED EGG-MANY CELLED...
 CELLS OF BLASTULA- REDISTRIBUTED AS
THE PRIMARY GERM
LAYERS(GASTULATION)
 IT CONTAIN THE MATERIAL OUT OF
WHICH THE EMBR...
 THE VERTEBRATE GROUPS
I. ANAMNIOTA- WITHOUT AMNION
 FISHES-LAMPREY ,
STURGEON,SHARK,BONY FISHES
 AMPHIBIANS-
FROGS,TOA...
MAMMALS – HAIR AND MAMMARY
GLANDS
• MONOTREMES- DUCK-BILL /ECHIDNA
• MARSUPIALS-OPOSSUM/ KANGAROO
• PLACENTALS-YOUNG NOUR...
-DOUBLING/FRACTIONATING PROCESS
PRODUCING COHERING,STICKY,
BLASTOMERES ARRANGED AROUND A
CENTRAL,FREE SPACE(BLASTOCOELE)
...
1. EQUAL-ISOLECITHAL OVA
-EQUAL SIZED BLASTOMERES
• AMPHIOXUS/MARSUPIAL/PLACENTAL
MAMMALS
2. UNEQUAL- MODERATELY
TELOLECIT...
B. PARTIAL- MEROBLASTIC OVA; ONLY
PROTOPLASMIC REGION DIVIDES.
1. DISCOIDAL-HIGHLY TELOLECITHAL
OVA
-MITOSIS RESTRICTED TO...
2. SUPERFICIAL – CENTROLECITHAL OVA;
DIVISION RESTRICTED TO THE
PERIPHERAL CYTOPLASMIC INVESTMENT
• ARTHROPODS
 AMPHIOXUS...
- FISH SHAPED; LOW CHORDATE
- EARLY STAGES OF DEVT. IS SIMILAR TO
SOME INVERTEBRATES
- ISOLECITHAL EGGS
- CLEAVAGE IS TOTA...
MODERATELY TELOLECITHAL (FAIR
AMOUNT OF YOLK)
- CLEAVAGE IS TOTAL BUT UNEQUAL
- UPPER 4 MICROMERES ARE SMALLER
THAN THE LO...
WALL IS MORE THAN 1 CELL THICK
BLASTOCOELE IS RELATIVELY SMALL;
LOCATED ABOVE CENTER DUE TO THE
THICK WALL OF THE VEGETA...
WITH LARGE EGGS
- CLEAVAGE IS PARTIAL & DISCOIDAL
- PRODUCES A DISCOIDAL PLATE OF CELLS
PERCHED ON THE SURFACE OF THE YOLK...
MARSUPIAL & PLACENTAL MAMMALS HAVE
EMBRYOS THAT ARE DEVELOPED WITH
DEPENDENCE ON THE MOTHER.
- EGGS ARE ISOLECITHAL
- CLEA...
- DIVISION BEGINS IN THE UTERINE TUBE
& COMPLETED IN THE UTERUS
- COMPLETED WITHIN A RANGE OF 70
HRS.(RABBIT) TO 190 HRS. ...
INVOLUTION , ELONGATION &
CONVERGENCE
- CHARACTERIZE GASTRULATION IN ALL
CHORDATES
ANIMAL
TYPE
TYPE OF
EGG
CLEA-
VAGE
BLAS-
TULA
BLASTU
-LA
CAVITY
METHO
DS OF
GASTRU
LATION
COMMEN
T ON
GASTRUL
ATION
AMPHIO...
BIRDS TELOLE-
CITHAL
(MASSIV
E YOLK)
PARTIAL;
DISCOI-
DAL
CELL-
DISC;
BLASTO-
DERM)
LIES ON
MASSIVE
YOLK
SHA-
LLOW;
DELAYE...
ECTODERM MESODERM
(INCLUDING
MESENCHYME)
ENTODERM
1. EPIDERMIS,INCLU
DING:
CUTANEOUS
GLANDS HAIR,
NAILS &LENS
2. EPITHELIU...
3. NERVOUS
TISSUE ,
INCLUDING;
HYPOPHYSIS,
CHROMAFFIN
TISSUE
6. BODY
CAVITIES
7.KIDNEY;
URETER
8.GONADS;
GENITAL
DUCTS
9.S...
Gametogenesis
Gametogenesis
Gametogenesis
Gametogenesis
Gametogenesis
Gametogenesis
Gametogenesis
Gametogenesis
Gametogenesis
Gametogenesis
Gametogenesis
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Gametogenesis

proliferation, divisions, mammals, humans, species

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Gametogenesis

  1. 1.  SEX CELL DIFFERENTIATION  OOGENESIS – EGG DIFFERENTIATION  SPERMATOGENESIS – SPERM DIFF. ◦ SPERMIOGENESIS – TRANSFORMATION OF THE MALE GAMETE
  2. 2.  IN MAN/MAMMALS, PRIMORDIAL GERM CELL COMES FROM YOLK SAC ENTODERM NEAR CAUDAL END OF BODY  FROM THERE THEY MIGRATE FORWARD THROUGH THE MESENCHYME OF THE MESENTERY AND INTO THE GENITAL RIDGE WHICH SOON BECOMES THE SEX GLAND  THEN PROLIFERATION
  3. 3.  PROLIFERATION IS PERIODIC (MONTHLY IN FEMALES) URING THE POTENTIAL CHILD-BEARING YEARS
  4. 4.  CELL PROLIFERATION – PRIMITIVE CELL REPEATEDLY DIVIDES  PERIOD OF GROWTH – RAPID ENLARGEMENT OF THE CELLS PRODUCED  PERIOD OF MATURATION – NUCLEAR CHANGES LIMITED TO THE FINAL TWO DIVISIONS
  5. 5.  ORIGIN OF THE FOLLICLES ◦ PRIMORDIAL CELLS (OOGONIA) PROLIFERATE WITHIN THE CORTEX OF THE OVARY ◦ SMALLER EPITH. CELLS, OF GERMINAL- EPITH ORIGIN ENCASED THE OOGONIA AND PRODUCED PRIMARY FOLLICLE ◦ AFTER BIRTH, FORMATION OF HUMAN OOGONIA STOPS THEN CELLS ARE NOW CALLED OOCYTES
  6. 6.  370,000 – AT BIRTH  190,000 – AT PUBERTY  26,000 – AT AGE 30  AFTER 30 OR MORE YEARS (CHILD- BEARING SPAN), FOLLICLES WILL NO LONGER BE SEEN
  7. 7.  NO ADVANCE BEYOND THE STAGE OF THE PRIMARY FOLLICLE UNTIL PUBERTY (14TH YEAR)  FEW HUNDREDS OF OOCYTES ARE LIBERATED PERIODICALLY DURING OVULATION
  8. 8.  GROWTH OF FOLLICLE STARTS SLOWLY BUT GROWS RAPIDLY 1-3 DAYS PRIOR TO RUPTURE  MATURATION – ACHIEVED BY MEIOSIS WITH 4 CELLS HAVING EQUAL NUCLEI WHILE THE CYTOPLASM IS UNEQUALLY DIVIDED
  9. 9.  1 LARGE RIPE OVUM  3 RUDIMENTARY OVA (POLAR BODIES) OR POLOCYTES  CYTOPLASM – GRANULAR AND CONTAINS FEW TO MANY INERT GRANULES  YOLK/DEUTOPLASM – MADE UP OF FATTY AND ALBUMINOUS SUBSTANCE; SERVES AS NOURISHMENT FOR THE EMBRYO
  10. 10.  YOLK – USEFUL IN CLASSIFYING EGGS. I. BASED ON RELATIVE ABUNDANCE OF YOLK: 1. SMALL 2. MEDIUM 3. LARGE
  11. 11. II. DISTRIBUTION OF YOLK IN CELLS: 1. ISOLECITHAL – EQUAL YOLK MEIOLECITHAL – LITTLE YOLK - INVERTEBRATES - ALL MAMALS EXCEPT LOWEST FORMS 2. TELOLECITHAL EGGS – ABUNDANT YOLK AND CONCENTRATED IN ONE HEMISPHERE
  12. 12. -INVERTEBRATES -ALL VERTEBRATES LOWER THAN MARSUPIALS - CHICK EGG 3. MEDIALECITHAL (MEDIUM YOLK) – MODERATE YOLK – AMPHIBIANS 4. MEGALECITHAL- LARGE, YOLK RICH EGGS OF BONY FISHES , REPTILES , BIRDS
  13. 13. 5. CENTROLECITHAL- DISTINCTIVE ARRANGEMENT OF YOLK, MASSED CENTRALLY BUT SORROUNDED BY A PERIPHERAL SHELL OF CLEAR CYTOPLASM. EGG POLARITY: ANIMAL POLE – SITE WHERE POLAR BODIES PINCH OFF
  14. 14. - VIGOROUS PART IN DEVT. & WHERE HIGHEST CAPACITY FOR ACTIVITY RESTS - VEGETAL POLE- SLUGGISH END OF CELL AND CONCERNED WITH THE DEVT. OF NUTRITIVE ORGANS - YOLK LADEN PROTECTIVE MEMBRANES: 1° MEMBRANE-CELL/PLASMA MEMBRANE
  15. 15. 2° MEMBRANE- ZONA PELLUCIDA 3° MEMBRANE –ADDED BY THE OVIDUCT AS THE EGG PASSES THROUGH IT - JELLY OF FROG’S EGGS - ALBUMEN OF RABBIT’S EGG - ALBUMEN AND SHELL OF HEN’S EGG
  16. 16. CELLULAR CORDS ( GERMINAL EPITHELIUM) TESTES TUBULES  SPERMATOGONIA (STEM CELLS)- LARGER  INDIFFERENT CELLS- SMALLER  PUBERTY – SOME SPERMATOGONIA REMAIN AS STEM CELLS WHILE OTHERS BECOME PRIMARY SPERMATOCYTE-2° SPERMATOCYTE-SPERMATID-SPERM
  17. 17.  DETACHED FROM SERTOLI CELLS AND ARE SET FREE INSIDE THE SEMINIFEROUS TUBULES  SPERM CELL- SMALLEST CELL IN MASS MADE UP OF HEAD, NECK & TAIL.  AT THE END OF MATURATION (MEIOSIS) THE DEVT. OF EGG IS COMPLETE AND THE EGG BECOMES FUNCTIONAL WHILE THE MALE GAMETE UNDERGOES A SERIES OF TRANSFORMATIONS BEFORE A FUNCTIONAL SPERM CELL IS DERIVED
  18. 18.  CHROMOSOME NUMBERS (2N) MAN=46 (DIPLOID CHROMOSOME#) (N) MAN=23 (HAPLOID CHROMOSOME#)  FEMALE -22 ORDINARY CHROMOSOME PAIR -23RD PAIR(SEX CHROMOSOME) (XX) PAIR  MALE 22 ORDINARY CHROMOSOME PAIR 23RD PAIR (XY) PAIR
  19. 19.  24 DIFFERENT KINDS OF CHROMOSOMES COMPARISON OF EGG & SPERM OF ANIMALS IN GENERAL
  20. 20. FEATURES OVUM SPERMATO- ZOON SIZE LARGE SMALL SHAPE SPHEROIDAL ELONGATED QUANTITY FEW (ONE) OFTEN IN MILLIONS MOTILITY NON-MOTILE VIGOROUS (FLAGELLATE) PROTECTION EGG ENVELOPES NONE
  21. 21. CYTOPLASM BULKY MINIMAL YOLK LITTLE TO MUCH NONE CENTRO- SOME DISAPPEARS RETAINED – CENTRIOLE & AXIAL FILAMENT MITOCHON- DRIA DIFFUSED IN THE BODY ONLY
  22. 22. GOLGI- APPARATUS DIFFUSED IN ACROSOME ONLY NUCLEUS OPEN STRUCTURED CONDENSED AS SPERM HEAD NUCLEOLUS TYPICAL INDISTINGUIS HABLE SEX DETERMININ G ROLE RARELY TWO KINDS(MOTH S/BIRDS) USUALLY TWO KINDS(MALE &FEMALE)
  23. 23.  INTERNAL FERTILIZATION -SMALL NUMBER OF EGGS  EXTERNAL FERTILIZATION -LARGE VOLUME OF EGGS TYPES OF BREEDING: • CONTINUOUS-ALL THOUGHOUT THE YEAR • SEASONAL/ANNUAL SPAWNING PERIOD • SPONTANEOUS- SEXUAL EXCITEMENT/PERIOD OF HEAT / ESTRUS
  24. 24. • PROVOKED OVULATION- INDUCED BY THE ACT OF COPULATION. • PERIODIC (INTERVALS OF 4 WEEKS) SPONTANEOUS  HUMAN FEMALE -OVULATION (14 YRS.) + 30 YEARS OF SEXUAL ACTIVITY  FOLLICLE RUPTURE- SIMILAR TO THE RUPTURE OF A BOIL; TAKES PLACE AT THE STIGMA
  25. 25. - HORMONAL FACTOR AND LOCAL WEAKENING OF FOLLICULAR WALL EGG TRANSPORT- MADE POSSIBLE BY HORMONAL CONTROL AND OVARY ACTIVITY. TIME OF OVULATION- MIDDLE OF THE CYCLE 28-DAY CYCLE 26-DAY CYCLE 30-DAY CYCLE
  26. 26.  EGG VIABILITY- FERTILIZABLE PERIOD IS LESS THAN ONE DAY – GENERATION TAKES PLACE CORPUS LUTEUM- OVARIAN STRUCTURE (COLLAPSED & FOLDED) VESICULAR FOLLICLE- MADE UP OF LUTEIN CELLS • CORPUS LUTEUM OF OVULATION • CORPUS LUTUEM OF PREGNANCY • CORPUS ALBICANS- WHITE SCAR LEFT MADE UP OF FIBROUS TISSUE.
  27. 27. • PSEUDOCOPULATION- INCREASES CERTAINTY OF UNION • COPULATION- SEXUAL EMBRACE SPERM STORAGE- ACCUMULATION AT EPIDIDYMIS(TRAVERSED IN 12 DAYS) SPERM DISCHARGE- EJACULATION(MALE CLIMAX DURING COITUS) SEMEN (SPERMATOZOA PLUS THE SECRETIONS FROM 3 ACCESSORY GLANDS:
  28. 28. • SEMINAL VESICLE • BULBO-URETHRAL GLAND • PROSTATE GLAND  3 ML EJACULATE-250,000,000 SPERMS SPERM TRANSPORT-LASHING, FLAGELLATED MOVEMENT ; WILL TRAVERSE UTERUS IN 70 MIN.(7 INCHES) SPERM VIABILITY= 1-2 DAYS
  29. 29.  IN VITRO- TWO WEEKS  HUMAN SEMEN(FROZEN IN GLYCEROL  AT - 70℃ (CAN SURVIVE FOR MANY MONTHS
  30. 30.  PROCESS WHEREBY 2 GAMETES FUSE TOGETHER TO CREATE A NEW INDIVIDUAL WITH A GENOME DERIVED FROM BOTH PARENTS  ACCOMPLISHES 2 SEPARATE ENDS; SEX (THE COMBINING OF GENES DERIVED FROM 2 PARENTS) AND REPRODUCTION (THE CREATION OF A NEW ORGANISM)  CONCEPTION CONSISTS OF 4 MAJOR EVENTS:
  31. 31.  1. CONTACT AND RECOGNITION BETWEEN SPERM AND EGG. THIS ENSURES THAT THE SPERM AND EGG ARE OF THE SAME SPECIES  2. REGULATION OF SPERM ENTRY INTO THE EGG. ONLY ONE SPERM CAN ULTIMATELY FERTILIZE THE EGG. THIS IS USUALLY ACCOMPLISHED BY ALLOWING ONLY ONE SPERM TO ENTER THE EGG AND INHIBITING ANY OTHERS FROM ENTERING
  32. 32.  3. FUSION OF THE GENETIC MATERIAL OF SPERM AND EGG  4. ACTIVATION OF EGG METABOLISM TO START DEVELOPMENT
  33. 33.  ANTON VAN LEEUWENHOEK – CO- DISCOVERER OF SPERM  NICOLAS HARTSOEKER – CO-DISCOVERER OF SPERM  DREW A PICTURE OF A PREFORMED HUMAN (HOMUNCULUS)  BELIEF THAT THE SPERM CONTAINED THE ENTIRE EMBRYONIC ORGANISM
  34. 34.  POOLING TOGETHER OF SPERM AND EGG NUCLEI • INVERTEBRATES ( ROTIFERS, CRUSTACEANS INSECTS) DEVELOP WITHOUT THE BENEFIT OF FERTILIZATION(PARTHENOGENESIS)
  35. 35.  RESULTS OF FERTILIZATON: 1. REASSOCIATION OF MALE AND FEMALE SETS OF CHROMOSOMES , RESTORING THEM TO THE FULL DIPLOID NUMBER. 2. SEX DETERMINATION 3. ACTIVATION OF OVUM INTO CELL DIVISION OR CLEAVAGE.
  36. 36.  SEX DETERMINATION – IS ESTABLISHED AT THE TIME OF FERTILIZATION  DURING MEIOSIS, CHROMOSOME NUMBER IS HALVED  22+X – FEMALE  22+X – MALE; 22+Y – MALE  22+X + 22+X = 44+2X  22+X + 22+Y = 44+X+Y
  37. 37.  PERIODS OF EARLY DEVELOPMENT: 1) GAMETOGENESIS 2) FERTILIZATION 3) CLEAVAGE 4) GASTRULATION  FERTILIZED EGG-MANY CELLED INDIVIDUAL(CLEAVAGE) - CELLS TYPICALLY ARRANGE THEMSELVES INTO A HOLLOW SPHERE, THE BLASTULA
  38. 38.  CELLS OF BLASTULA- REDISTRIBUTED AS THE PRIMARY GERM LAYERS(GASTULATION)  IT CONTAIN THE MATERIAL OUT OF WHICH THE EMBRYO AND ALL ITS PARTS WILL DIFFERENTIATE. • ECTO • MESO • ENTO/ENDODERM
  39. 39.  THE VERTEBRATE GROUPS I. ANAMNIOTA- WITHOUT AMNION  FISHES-LAMPREY , STURGEON,SHARK,BONY FISHES  AMPHIBIANS- FROGS,TOAD,SALAMANDERS II. AMNIOTA- WITH AMNION  REPTILES -LIZARD,CROCODILES,SNAKES,TURTLES
  40. 40. MAMMALS – HAIR AND MAMMARY GLANDS • MONOTREMES- DUCK-BILL /ECHIDNA • MARSUPIALS-OPOSSUM/ KANGAROO • PLACENTALS-YOUNG NOURISHED IN THE UTERUS VIA PLACENTA • PRIMATES- WITH NAILS (LEMUR,MONKEY,APE AND MAN) – SUBORDER ANTHROPOIDA
  41. 41. -DOUBLING/FRACTIONATING PROCESS PRODUCING COHERING,STICKY, BLASTOMERES ARRANGED AROUND A CENTRAL,FREE SPACE(BLASTOCOELE)  EGG CLASSIFICATION ON THE BASIS OF ABUNDANCE AND YOLK DISTRIBUTION: A. TOTAL- HOLOBLASTIC OVA; ENTIRE OVUM DIVIDES
  42. 42. 1. EQUAL-ISOLECITHAL OVA -EQUAL SIZED BLASTOMERES • AMPHIOXUS/MARSUPIAL/PLACENTAL MAMMALS 2. UNEQUAL- MODERATELY TELOLECITHAL OVA • LOWER FISHES / AMPHIBIANS
  43. 43. B. PARTIAL- MEROBLASTIC OVA; ONLY PROTOPLASMIC REGION DIVIDES. 1. DISCOIDAL-HIGHLY TELOLECITHAL OVA -MITOSIS RESTRICTED TO THE ANIMAL POLE. • HIGHER FISHES/REPTILES/BIRDS/ MONOTREME MAMMALS
  44. 44. 2. SUPERFICIAL – CENTROLECITHAL OVA; DIVISION RESTRICTED TO THE PERIPHERAL CYTOPLASMIC INVESTMENT • ARTHROPODS  AMPHIOXUS-FISH-SHAPED; LOW CHORDATE  AMPHIBIANS  REPTILES/ BIRDS  MAMMALS
  45. 45. - FISH SHAPED; LOW CHORDATE - EARLY STAGES OF DEVT. IS SIMILAR TO SOME INVERTEBRATES - ISOLECITHAL EGGS - CLEAVAGE IS TOTAL AND NEARLY EQUAL - SUBSEQUENT CELL DIVISIONS IN ALTERNATE PLANES PRODUCES 32,64 ANO 128 CELL STAGES - SIZE OF CELLS ARE PROGRESSIVELY DIMINISHED WHILE THE CENTRAL CAVITY ENLARGES TO FORM THE BLASTOCOELE
  46. 46. MODERATELY TELOLECITHAL (FAIR AMOUNT OF YOLK) - CLEAVAGE IS TOTAL BUT UNEQUAL - UPPER 4 MICROMERES ARE SMALLER THAN THE LOWER 4 - FORMS A CENTRAL BLASTOCOELE WHERE BLASTOMERES AT THE ANIMAL POLE ARE SMALLER; LARGER & FEWER AT VEGETAL POLE
  47. 47. WALL IS MORE THAN 1 CELL THICK BLASTOCOELE IS RELATIVELY SMALL; LOCATED ABOVE CENTER DUE TO THE THICK WALL OF THE VEGETAL POLE
  48. 48. WITH LARGE EGGS - CLEAVAGE IS PARTIAL & DISCOIDAL - PRODUCES A DISCOIDAL PLATE OF CELLS PERCHED ON THE SURFACE OF THE YOLK AND SEPERATED FROM IT BY A CLEFT - CLEAVAGE PRODUCES A MODIFIED BLASTULA( DISCOBLASTULA) WITH THE CELLULAR CAP CALLED A BLASTOCOELE
  49. 49. MARSUPIAL & PLACENTAL MAMMALS HAVE EMBRYOS THAT ARE DEVELOPED WITH DEPENDENCE ON THE MOTHER. - EGGS ARE ISOLECITHAL - CLEAVAGE TAKES PLACE IN THE ZONA PELLUCIDA & THE BLASTOMERES ACCOMMODATE THEMSELVES TO THE SPHEROIDAL CAVITY. - CLEAVAGE IS TOTAL AND NEARLY EQUAL/
  50. 50. - DIVISION BEGINS IN THE UTERINE TUBE & COMPLETED IN THE UTERUS - COMPLETED WITHIN A RANGE OF 70 HRS.(RABBIT) TO 190 HRS. FOR THE COW.
  51. 51. INVOLUTION , ELONGATION & CONVERGENCE - CHARACTERIZE GASTRULATION IN ALL CHORDATES
  52. 52. ANIMAL TYPE TYPE OF EGG CLEA- VAGE BLAS- TULA BLASTU -LA CAVITY METHO DS OF GASTRU LATION COMMEN T ON GASTRUL ATION AMPHIOX US ISOLECIT HAL (LITTLE YOLK) TOTAL; EQUAL SPHERE; WALL A SINGLE LAYER SPHERI- CAL RELATIVE LY LARGE INVAGI- NATION; INVOLU- TION VIA BLASTO- PORE EARLY INNER LAYER IS A COMPO- SITE AMPHI- BIANS TELOLE- CITHAL (MODE- RATE YOLK) TOTAL; UNEQUA L SPHERE; WALL LAYERED ;THICK- NESS VARIES SPHERI- CAL; RELATIVE LY SMALL; ECCEN- TRIC CHIEFLY IN VOLU- TION VIA BLASTO- PORE INVOLU- TED LAYERS ARE SEPARA- TE FROM START
  53. 53. BIRDS TELOLE- CITHAL (MASSIV E YOLK) PARTIAL; DISCOI- DAL CELL- DISC; BLASTO- DERM) LIES ON MASSIVE YOLK SHA- LLOW; DELAYE D UNTIL ENTO- DERM FORMS DELAMI- NATION; INVOLU- TION VIA PRIMI- TIVE STREAK OCCURS IN TWO STAGES; MODI- FIED AMPHIBI AN STYLE MAMALS (EXCEPT LOWEST) ISOLECI- THAL (LITTLE YOLK) TOTAL; EQUAL BLASTO- CYST, WITH INNER CELL MASS MERGED WITH YOLK- FREE BLASTO CYST CAVITY DELAMI NATION; INVOLU- TION VIA PRIMI- TIVE STREAK OCCURS IN TWO STAGES; BASICA- LLY SIMILAR TO BIRDS
  54. 54. ECTODERM MESODERM (INCLUDING MESENCHYME) ENTODERM 1. EPIDERMIS,INCLU DING: CUTANEOUS GLANDS HAIR, NAILS &LENS 2. EPITHELIUM OF: SENSE ORGANS. NASAL CAVITY;SINUSES. MOUTH , INCLUDING: ORAL GLANDS; ENAMEL, 1. MUSCLE(ALL TYPES) 2. CONNECTIVE TISSUE ; CARTILAGE;BONE ;NOTOCHORD 3. BLOOD;BONE ARROW 4. LYMPHOID TISSUE. EPITHELIUM OF: 5.BLOOD VESSELS; LYMPHATICS. EPITHELIUM OF: 1. PHARYNX,INCLU DING: ROOT OF TONGUE , AUDITORY TUBE, ETC. TONSILS; THYROID PARATHYROIDS ; THYMUS 2. LARYNX; TRACHEA; LUNGS
  55. 55. 3. NERVOUS TISSUE , INCLUDING; HYPOPHYSIS, CHROMAFFIN TISSUE 6. BODY CAVITIES 7.KIDNEY; URETER 8.GONADS; GENITAL DUCTS 9.SUPRARENAL 10.JOINT CAVITIES , ETC 3.DIGESTIVE TUBE , INCLUDING : ASSOCIATED GLANDS 4.BLADDER 5.VAGINA(ALL?), VESTIBULE. 6.URETHRA , INCLUDING: ASSOCIATED GLANDS.

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