The male reproductive system includes the testes, which produce sperm and hormones. Additional structures like the vas deferens, seminal vesicles, prostate and penis work together in ejaculation. The testes contain seminiferous tubules where spermatogenesis occurs to produce sperm. During ejaculation, seminal fluid containing sperm and secretions from the seminal vesicles and prostate mix to form semen. The penis contains erectile tissue that fills with blood to cause an erection, enabling delivery of semen during intercourse.

1. Introduction: Male Reproductive System

2. Male Reproductive System is responsible for: Production, nourishment and temporary storage of the haploid male gametes(spermatozoa) Suspension of spermatozoa to the female genital system Production of male sex hormones

3. Male Genital System Comprises: Testes- produce spermatozoa, synthesize and secrete androgens

4. Epididymis, Vas deferens, Ejaculatory duct and part of male urethra- forming ductal system for the carriage of spermatozoa to the exterior

6. Seminal Vesicles, Prostate Gland and Cowper’s Gland- providing fluid nutrients to nourish spermatozoa Cowper’s gland

8. SPERMATOGENESIS process by which male primary germ cells undergo division, and produce a number of cells termed spermatogonia, from which the primary spermatocytes are derived. Each primary spermatocyte divides into two secondary spermatocytes, and each secondary spermatocyte into two spermatids or young spermatozoa. These develop into mature spermatozoa, also known as sperm cells. Thus, the primary spermatocyte gives rise to two cells, the secondary spermatocytes, and the two secondary spermatocytes by their subdivision produce four spermatozoa

9. ACCESSORY GLANDS OF THE MALE REPRODUCTIVE TRACT

11. Lipofuscin granules from dead epithelial cells give the secretion its yellowish color.

12. About 50-70%of the seminal fluid in humans originates from the seminal vesicles, but is not expelled in the first ejaculate fractions which are dominated by spermatozoa and prostatic fluid.

14. Wall of the vesicles is composed of connective tissue capsule with an underlying layer of smooth muscle A plexus of sympathetic nerve fibers and small ganglia can be found on the vesicle wall

15. Structure: coiled or convoluted tube with numerous diverticula along its length resulting in a lumen of labyrinth complexity in sections, the mucosa forms thin folds from which secondary and tertiary folds project into the lumen

16. however, all of these recesses open into a wider central portion of the lumen pseudostratified epithelium has low columnar or cuboidal cells with smaller numbers of rounded cells between their bases

17. surface of epithelium bears microvilli some of the cells have a single flagellum projecting into the lumen from a pair of centrioles in their cytoplasm they contain numerous slender mitochondria, well-developed granular endoplasmic reticulum and abundant secretory granules

18. small lipid droplets and aggregations of lipochrome pigment are commonly found in the basal cytoplasm (pigment first appears at puberty; may be sufficiently abundant in older adults to give the interior of the vesicles a brownish color in the fresh state)

23. Functions: to store and secrete a slightly alkaline fluid, milky or white in appearance The fluid usually constitutes 20-30% of the volume of the semen along with spermatozoa and seminal vesicle fluid. alkalinity of semen helps neutralize the acidity of the vaginal tract, prolonging the lifespan of sperm. Secretion of prostate contains acid phosphatase, amylase and fibrinolysin

24. Description: largest of the accessory glands in males its sectretion together with the seminal vesicle contributes to the volume of ejaculation size: horse chestnut

25. Zones: Lobes:

28. surrounds urethra at its origin from the urinary bladder around the gland: thin capsule formed by dense connective tissue and extends into it as its stoma capsule and stoma: both contain smooth muscle, fibroblasts and collagen

29. compound tubuloacinar glands are arranged in concentric zones 30-40 short glands (around urethra) discharge their secretion through separate openings on either side of colliculusseminalis: Mucosal Glands Peripheral to these is a zone of longer, branching submucosal glands(sharing a smaller number of ducts) Outside of these are the main glands( make up the greater part of the prostate)

30. Tubuloacinar Units Sometimes narrow or wider in form: variable Branching folds or papillae of the mucosa project into the lumen Epithelium: simple or pseudostratified columnar but may be reduced to low cuboidal or squamous in dilated or cystic dilatations Cells contain abundant rough ER, numerous secretory granules

32. In the Lumen of Glands: Corpora Amylacea or Prostatic Concretions- ovoid or spherical bodies - These are glycoprotein in composition - May become a site of calcium in deposition - More common in prostate of older men - No known significance

33. Bulbourethral Glands Cowper’s glands *a neglected gland Paired Partially embedded in the muscle of urogenital diaphragm Compound tubuloacinar glands Less than 1cm in diameter Each open by a single duct into the floor of proximal portion of the cavernous urethra

34. Functions: each gland produces a clear, viscous secretion during sexual arousal, known as pre-ejaculate helps to lubricate the urethra for spermatozoa to pass through neutralizing traces of acidic urine in the urethra helps flush out any residual urine or foreign matter *the fluid is capable of picking up sperm

35. Glands Branched and distorted tubules ( blind ends usually dilated to form alveoli Ampullae: tubules comprising the small lobules of the gland that converge on wider channels Duct arises from confluence of the ampullae of several lobules Prominent connective tissue partitions between the lobules have collagenous and elastic fibers; also both striated and smooth muscle fibers They are lined by tall, mucus secreting epithelium

37. Small ducts and Ampullae Lined by cuboidal or columnar epithelial cells Lumenal surface: irregular with short microvilli Basolateral surfaces: corrugate and interlock with similar irregularities on adjacent cells Epithelium: with patches of mucous cells In the apical cytoplasm: few cells of electron-dense secretory granules (resembling serous cells) Larger excretory ducts: lined by pseudostratified epithelium (with patches of mucous cells may be found)

38. Secretion emitted at the onset of ejaculation and makes a small contribution to the initial fraction of the semen Clear, mucus-like, viscous fluid Can be drawn out into a long thin thread on contact Said to have a lubricant function

40. SUMMARY

42. Penis the external sex organ of the male through which both urine and semen pass Thin skin is composed of three columns of erectile tissue, each enclosed by its own dense, fibrous connective tissue capsule, the tunica albuginea. Superficial to the tunica is an outer sheath of connective tissue, the penile fascia Two of the columns of erectile tissue, the corpora cavernosa, are positioned dorsally; their tunicae albugineae are discontinuous in places, permitting communication between their erectile tissues. Third column of erectile tissue, the corpus spongiosum, is positioned ventrally. Because the CS houses the penile portion of the urethra, it is also called the corpus cavernosumurethrae.

43. Penis CS ends distally in an enlarged, bulbous portion, the glans penis (head of the penis). The tip of the glans penis is pierced by the end of the urethra as a vertical slit. Three corpora are surrounded by a common loose connective tissue sheath, but no hypodermis, and are covered by thin skin. Skin continues distal to the glans penis to form a retractable sheath, the prepuce. When an individual is circumcised, it is the prepuce that is removed. Erectile tissue of the penis contains numerous variably shaped, endothelially lined spaces. Vascular spaces of the corpora cavernosa are larger centrally and smaller peripherally, near the tunica albuginea. Vascular spaces of the corpus spongiosum are similar in size throughout its extent.

44. Corpus spongiosum At its end the corpus spongiosum expands, forming the glans penile urethra is lined with pseudostratified columnar epithelium. Small mucus-secreting urethra glands (glands of Littre) are found along the length of the penile urethra. In uncircumcised men the surface of the glans is covered by the prepuce or foreskin, a retractile fold of thin skin with sebaceous glands in the internal fold.

47. Glanspenis In the glans, it becomes stratified squamous epithelium continuous with that of the thin epidermis covering the glans. Consist of dense connective tissue containing a plexus of of large anastomosing veins with both circular and longitudinal smooth muscles in their walls. Covered by a fold of skin called the prepuce

48. Histology of the Glans and prepuce: keratinized squamous epithelium. Histology of the erectile tissue: the corpora contain septa of smooth muscle, which form bizarrely shaped cavities. Vascular endothelium lines the septa and cavities. The afferent arteries for the erectile tissue possess a strong muscularis.

49. Levels of the Glans Epithelium Lamina Propria Corpus Spongiosum Tunica Albuginea * Corpus Cavernosum *

50. Epithelium Both circumcised and intact (uncircumcised) men have partially keratinized stratified squamous epithelium five to sixlayers thick Lamina Propria In the glans, the loose connective tissue of the penile fascia and the fibrous tunica albuginea are lacking so that the lamina propria adheres firmly to the underlying corpus spongiosum Corpus spongiosum. The interstitial fibrous connective tissue is more abundant and contains more elastic fibers than in the corpus cavernosum.

51. Prepuce covers the glans penis. This is the skin that is cut away when a circumcision is done. Anatomic Levels of the Foreskin Epidermis Dermis Dartos Lamina propria Epithelium

52. prepuce The outside of the foreskin is a continuation of the skin on the shaft of the penis, but the inner foreskin is a mucous membrane like the inside of the eyelid or the mouth Smooth muscle fibres keep it close to the glans but make it highly The presence of Meissner's corpuscles (a type of nerve ending) has been reported. elastic

55. Corpora cavernosa Sponge-like system of irregular shaped vascular spaces fed by afferent arteries and veins covered by a resistant layer of dense connective tissue, the tunica albuginea Between the lower surfaces of the corpora cavernosa there is a deeper groove occupied by the corpus cavernosumurethrae The corpora cavernosa and the corpus spongiosum are both composed of erectile tissue, which contains a large number of venous cavernous spaceslined with endothelial cells and separated by trabeculae of connective tissue fibers and smooth muscle cells.

57. Tunica albuginea Thinner in the corpus cavernosumurethrae Has circularly arranged smooth muscles cells in the inner layer , longitudinally in the outer layer Forms a fibrous partition between the two corpora cavernosa Has elastic fibers

58. Skin covering the Penis Thin Abundant subcutaneous layer containing some smooth muscles Devoid of hair Limited number of sweat glands

59. The Penis

61. MECHANISM OF ERECTION Penile erection involves filling the cavernous spaces of the corpora cavernosa and corpus spongiosum with blood. Initiated by external stimuli to the CNS and is controlled by autonomic nerve input to smooth muscle in vascular walls of the penis

62. MECHANISM OF ERECTION Parasympathetic stimulation relaxes muscle in the trabeculae and dilates the helicine arteries, leading to increased blood flow into the cavernous spaces. The filled spaces compress the venules and veins against the dense tunica albuginea, blocking outflow of the blood and producing tumescence and rigidity in the cylinders of erectile tissue. Beginning with ejaculation, the firing of sympathetic nerves stimulates constriction of the helicine arteries, decreasing blood flow into the spaces, lowering the pressure there and allowing the veins to open and drain most blood from the erectile tissue.