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Male reproductive system

  1. Male Reproductive System
  2. Male Reproductive System • The reproductive system in men has components in the abdomen, pelvis, and perineum.
  3. • The major components are a testis, epididymis, ductus deferens, and ejaculatory duct on each side, and the urethra and penis in the midline. • Three types of accessory glands are associated with the system: – A single prostate; – A pair of seminal vesicles; – A pair of bulbourethral glands.
  4. Male Reproductive System
  5. The scrotum • The scrotum is an outpouching of the lower part of the anterior abdominal wall. • It contains the testes, the epididymides, and the lower ends of the spermatic cords.
  6. The scrotum • It is divided on its surface into two compartments by a raphé, which is continued forward to the under surface of the penis, and backward, along the middle line of the perineum to the anus. • Each compartment contains one of the two testes, and one of the epididymides.
  7. The scrotum • The wall of the scrotum has the following layers: – Skin – Superficial fascia – Spermatic fasciae – Tunica vaginalis
  8. The scrotum Skin •The skin of the scrotum is thin, wrinkled, and pigmented and forms a single pouch. A slightly raised ridge in the midline indicates the line of fusion of the two lateral labioscrotal swellings. Superficial fascia •This is continuous with the fatty and membranous layers of the anterior abdominal wall. •The fat is replaced by smooth muscle called the dartos muscle. •This is innervated by sympathetic nerve fibers and is responsible for the wrinkling of the overlying skin.
  9. The scrotum Spermatic fasciae •It has three layers which lie beneath the superficial fascia and are derived from the three layers of the anterior abdominal wall on each side. •The external spermatic fascia is derived from the aponeurosis of the external oblique muscle; the cremasteric fascia is derived from the internal oblique muscle; and, finally, the internal spermatic fascia is derived from the fascia transversalis. Tunica vaginalis This lies within the spermatic fasciae and covers the anterior, medial, and lateral surfaces of each testis.
  10. Lymph Drainage of the Scrotum • Lymph from the skin and fascia, including the tunica vaginalis, drains into the superficial inguinal lymph nodes .
  11. Testes • Testis has ellipsoid- shaped. • Testes develop in the abdomen and move before birth into the scrotum. • The left testis usually lies at a lower level than the right.
  12. Testes • The testis are covered by: • A closed sac of peritoneum (the tunica vaginalis), which originally connected to the abdominal cavity. Normally after testicular descent, the connection closes, leaving a fibrous remnant. • It is covered by a fibrous capsule called the tunica albuginea.
  13. Testes • In the inner surface of the capsule is a series of fibrous septa that divide the interior of the organ into lobules. • Lying within each lobule are 1 to 3 coiled seminiferous tubules. • The tubules open into a network of channels called the rete testis. • Small efferent ductules connect the rete testis to the upper end of the epididymis.
  14. Testes
  15. Epididymis • The epididymis is a single, long coiled duct that courses along the posterolateral side of the testis. • The tunica vaginalis covers the epididymis with the exception of the posterior border.
  16. Epididymis • Structurally, epididymis divided into : – Head – Body – tail
  17. Epididymis It has two distinct components: –The efferent ductules, which form an enlarged coiled mass that sits on the posterior superior pole of the testis and forms the head of the epididymis; –The true epididymis, which is a single, long coiled duct into which the efferent ductules all drain, and which continues inferiorly along the posterolateral margin of the testis as the body of epididymis and enlarges to form the tail of epididymis at the inferior pole of the testis.
  18. Arterial Blood Supply of the Testis and Epididymis • The testicular artery is a branch of the abdominal aorta.
  19. • The testicular veins emerge from the testis and the epididymis as a venous network, the pampiniform plexus. • This becomes reduced to a single vein as it ascends through the inguinal canal. • The right testicular vein drains into the inferior vena cava, and the left vein joins the left renal vein.
  20. Lymphatic Drainage of The Testes • Lymphatic drainage of the testes is to the para- aortic lymph nodes.
  21. Ductus deferens • (Latin: "carrying-away vessel"), also called vas deferens. • The ductus deferens is a long muscular duct that transports spermatozoa from the tail of the epididymis to the ejaculatory duct.
  22. Ductus deferens course • The vas arises from the tail of the epididymis and traverses the inguinal canal to the deep ring, passes downwards on the lateral wall of the pelvis almost to the ischial tuberosity and turns medially to cross the ureter posterior to the bladder. • It continues inferomedially along the base of the bladder, anterior to the rectum, almost to the midline, where it is joined by the duct of the seminal vesicle to form the ejaculatory duct.
  23. Ductus deferens course • The terminal part of the vas deferens is dilated to form the ampulla of the vas deferens. • The ejaculatory duct penetrates through the prostate gland to connect with the prostatic urethra.
  24. Seminal vesicle • The seminal vesicles are an accessory gland of the male reproductive system . • The seminal vesicles are two lobulated organs about 2 in. (5 cm) long lying on the posterior surface of the bladder .
  25. Seminal vesicle • On the medial side of each vesicle lies the terminal part of the vas deferens. • Posteriorly, the seminal vesicles are related to the rectum. • Inferiorly, each seminal vesicle narrows and joins the vas deferens of the same side to form the ejaculatory duct.
  26. Blood Supply of Seminal vesicle Arteries •The arterial blood supply from, the inferior vesicle and middle rectal arteries. Veins • The veins drain into the internal iliac veins.
  27. Ejaculatory Ducts • The two ejaculatory ducts are each less than 1 in. (2.5 cm) long and are formed by the union of the vas deferens and the duct of the seminal vesicle. • The ejaculatory ducts pierce the posterior surface of the prostate and open into the prostatic part of the urethra, close to the margins of the prostatic utricle; their function is to drain the seminal fluid into the prostatic urethra.
  28. Semen • Semen is a milky white, somewhat sticky mixture of sperm, testicular fluid, and accessory gland secretions. The liquid provides a transport medium and nutrients and contains chemicals that protect and activate the sperm and facilitate their movement.
  29. Semen contains several substances that play many roles: • Prostaglandins decrease the viscosity of mucus guarding the entry (cervix) of the uterus and stimulate reverse peristalsis in the uterus, facilitating sperm movement through the female reproductive tract. • The hormone relaxin and certain enzymes in semen enhance sperm motility. • Contained ATP provides energy. • Certain ingredients suppress the immune response in the female’s reproductive tract.
  30. • Antibiotic chemicals destroy some bacteria. • Clotting factors in semen coagulate it just after it is ejaculated. Coagulation causes the sperm to stick to the walls of the vagina and prevents the initially immobile sperm from draining out of the vagina. Soon after semen coagulates, fibrinolysin liquefies the sticky mass and the sperm swim out and begin their journey through the female duct system
  31. The Bulbo-Urethral Glands • The bulbo-urethral glands are pea-sized glands located inferior to the prostate in the urogenital diaphragm • They produce a thick, clear mucus, some of which drains into the spongy urethra and lubricates the glans penis when sexually excited. • The mucus neutralizes traces of acidic urine and lubricates the urethra just prior to ejaculation.
  32. Prostate • The prostate is an unpaired accessory structure of the male reproductive system that surrounds the urethra in the pelvic cavity . • It lies immediately inferior to the bladder, above the urogenital diaphragm, posterior to the pubic symphysis, and anterior to the rectum.
  33. Prostate • The prostate is shaped like an inverted rounded cone with a larger base, which is continuous above with the neck of the bladder, and a narrower apex, which rests below on the pelvic floor. • The inferolateral surfaces of the prostate are in contact with the levator ani muscles that together cradle the prostate between them.
  34. Prostate
  35. Prostate • The two ejaculatory ducts pierce the upper part of the posterior surface of the prostate to open into the prostatic urethra at the lateral margins of the prostatic utricle.
  36. Relations of Prostate Superiorly •The base of the prostate is continuous with the neck of the bladder. •The urethra enters the center of the base of the prostate. Inferiorly • The apex of the prostate lies on the upper surface of the urogenital diaphragm. • The urethra leaves the prostate just above the apex on the anterior surface
  37. Relations of Prostate Anteriorly •The prostate is related to the symphysis pubis. •The prostate is connected to the posterior aspect of the pubic bones by the puboprostatic ligaments. Laterally •The prostate is embraced by the anterior fibers of the levator ani. Posteriorly •The prostate is closely related to the anterior surface of the rectal ampulla and is separated from it by the rectovesical septum (fascia of Denonvilliers).
  38. Structure of the Prostate • Enclosed within thin dense fibrous capsule • Inner loose sheath derived from pelvic fascia is prostatic sheath͟ – Continuous inferiorly with superior fascia of urogenital diaphragm – Posteriorly it is part of rectovesical septum – Separates bladder, seminal vesicles and prostate from rectum • Prostatic venous plexus lies between fibrous capsule and prostatic sheath.
  39. Structure of the Prostate Prostate divided into: – Two lateral lobes – One median lobe – Anterior and posterior lobes
  40. Structure of the Prostate • Anterior – Tissue lying anterior to urethra – No glands; fibromuscular tissue only • Median – Cone-shaped region between ejaculatory ducts and urethra • Lateral (left & right) – Main mass of gland, continuous posteriorly – Separated by prostatic urethra • Posterior – Describes postero-medial part of lateral lobes palpable through rectum on DRE.
  41. Functions of Prostate • During ejaculation, prostatic smooth muscle contracts, squeezing the prostatic secretion into the prostatic urethra via several ducts. This fluid plays a role in activating sperm and accounts for up to one-third of the semen volume. It is a milky, slightly acid fluid that contains citrate (a nutrient source), several enzymes (including fibrinolysin, hyaluronidase, and acid phosphatase), and prostate-specific antigen (PSA).
  42. Blood Supply of The Prostate • Arterial supply – Arteries derived from internal pudenal, inferior vesical and middle rectal arteries (branches of internal iliac) • Venous drainage – Veins form prostatic venous plexus around sides and base of prostate – located between capsule and sheath – Drains into internal iliac veins – Also communicates with vesical venous plexus and vertebral venous plexuses.
  43. Lymphatics and innervation of Prostate gland • Lymphatic drainage – Lymph vessels terminate in internal iliac and sacral lymph • nodes – Some vessels from posterior surface pass with lymph • vessels froŵ ďladder to exterŶal iliaĐ LN’s • Innervation – Parasympathetic fibres arise from pelvic splanchnic nerves – Sympathetic fibres from inferior hypogastric plexuses
  44. Penis • The penis is a pendulous organ suspended from the front and sides of the pubic arch and containing the greater part of the urethra.
  45. Penis • It consists of internal root, external shaft, & glans. – Root: the portion of the penis that extends internally into the pelvic cavity. – Shaft: the length of the penis between the glans and the body. – Glans: the head of the penis; has many nerve endings. • Foreskin: a covering of skin over the penile glans.
  46. Penis
  47. Penis • The root of penis consists of the two crura, which are proximal parts of the corpora cavernosa attached to the pubic arch, and the bulb of penis, which is the proximal part of the corpus spongiosum anchored to the perineal membrane.
  48. Penis • The body of the penis is essentially composed of three cylinders of erectile tissue enclosed in a tubular sheath of fascia (Buck's fascia). • The erectile tissue is made up of two dorsally placed corpora cavernosa and a single corpus spongiosum applied to their ventral surface . • At its distal extremity, the corpus spongiosum expands to form the glans penis, which covers the distal ends of the corpora cavernosa. • On the tip of the glans penis is the slitlike orifice of the urethra, called the external urethral meatus.
  49. Penis
  50. External penile structures • Corona: the rim of the penile glans. • Frenulum: thin strip of skin connecting the glans to the shaft on the underside of the penis. Both are highly sensitive areas to the touch
  51. Blood Supply of The Penis Arteries •The corpora cavernosa are supplied by the deep arteries of the penis ; the corpus spongiosum is supplied by the artery of the bulb. •In addition, there is the dorsal artery of the penis. •All the above arteries are branches of the internal pudendal artery. Veins • The veins drain into the internal pudendal veins.
  52. Lymphatics and innervation of The Penis Nerve Supply Sensation •The nerve supply is from the pudendal nerve and the pelvic plexuses. Erectile function •Parasympathetic(excitat ory) •Sympathetic (inhibitory) Lymph Drainage •The skin of the penis is drained into the medial group of superficial inguinal nodes. •The deep structures of the penis are drained into the internal iliac nodes.
  53. Analagous structures in male and female sexual anatomy Male Glans Foreskin Shaft Clitoris Clitoral hood Scrotal sac Testes Female Labia minora Labia majora Ovaries
  54. Physiology of the Male Reproductive System The chief phases of the male sexual response are 1. Erection of the penis, which allows it to penetrate the female vagina 2. Ejaculation, which expels semen into the vagina
  55. Erection • Erection, enlargement and stiffening of the penis, results from engorgement of the erectile bodies with blood. It happens because of the parasympathetic function of arteriole. • Sexual excitement triggers a parasympathetic reflex that promotes release of nitric oxide (NO) locally. • Nitric oxide relaxes smooth muscle in the penile blood vessel walls, dilating these arterioles, and the erectile bodies fill with blood.
  56. • Expansion of the corpora cavernosa of the penis compresses their drainage veins, retarding blood outflow and maintaining engorgement. • The corpus spongiosum expands but not nearly as much as the cavernosa. Its function is to keep the urethra open during ejaculation. • The erect penis not bend or fold during intercourse. The longitudinal and circular arrangement of collagen fibers surrounding the penis prevents this problem.
  57. • Ejaculation • Ejaculation is the propulsion of semen from the male duct system. • Although erection is under parasympathetic control, ejaculation is under sympathetic control. • When impulses provoking erection reach a critical level, a spinal reflex is initiated, and a massive discharge of nerve impulses occurs over the sympathetic nerves serving the genital organs
  58. 1. The bladder sphincter muscle constricts, preventing expulsion of urine or reflux of semen into the bladder. 2. The reproductive ducts and accessory glands contract, emptying their contents into the urethra. 3. Semen in the urethra triggers a spinal reflex through somatic motor neurons. The bulbospongiosus muscles of the penis undergo a rapid series of contractions, propelling semen from the urethra at a speed of up to 500 cm/s (200 inches/s, close to 11 mi/h). These rhythmic contractions are accompanied by intense pleasure and many systemic changes, such as generalized muscle contraction, rapid heartbeat, and elevated blood pressure.
  59. Spermatogenesis. • The process of spermatogenesis encompasses the phases through the production of sperm. Conversion of the haploid spermatids to sperm cells is specifically called spermiogenesis. • Throughout spermatogenesis, descendants of the same spermatogonium remain closely attached to one another by cytoplasmic bridges. They are also surrounded by and connected to nonreplicating supporting cells called sustentocytes or Sertoli cells, which extend from the basal lamina to the tubule lumen.
  60. PHASES OF SPERMATOGENESIS • Spermatogonial Phase (Mitosis) • Spermatocyte Phase/Spermatocytosis (Meiosis) • Spermatid Phase (Spermiogenesis) 64
  61. PHASE I-Spermatogonial Phase 65
  63. PHASE II- MEOSIS 67 Prophase-22 days Largest cell
  65. SPERMATOGENESIS Cytokinesis is incomplete Spermatogonial Phase Spermatocyte phase Spermiogenesis phase 69
  66. SPERMATOGENESIS Cytokinesis is incomplete Spermatogonial Phase Spermatocyte phase Spermiogenesis phase 70
  67. The sustentocytes: • Provide nutrients and essential signals to the dividing cells, even telling them to live or die • Move the cells along to the lumen • Secrete testicular fluid (rich in androgens and metabolic bacids) that provides the transport medium for sperm in the lumen • Phagocytize faulty germ cells and the excess cytoplasm sloughed off as the spermatids transform into sperm • Produce chemical mediators (inhibin and androgen-binding protein) that help regulate spermatogenesis
  68. Transformation of a spermatid intoa functionalsperm. The stepwise process of spermiogenesis: 1. The Golgi apparatus packages the acrosomal enzymes, 2. The acrosome forms at the anterior end of the nucleus and the centrioles gather at the opposite end of the nucleus, 3. Microtubules elaborate to form the flagellum, 4. Mitochondria multiply and take up position around the proximal portion of the flagellum, and 5. Excess cytoplasm sloughs off. 6. Structure of an immature sperm than has just been released from a sustentocyte. 7. Structure of a fully mature sperm.