Reproductive Physiology III: Male Reproduction Part 1 PDF

13/01/24 Reproductive Physiology III: male reproduction: part 1 Learning objective: review the anatomy of the male genital tract in relation to its function in reproduction. The male reproductive system: This consists of: External genitalia: penis and scrotum. Internal genitalia: testes, epididymis,...

13/01/24 Reproductive Physiology III: male reproduction: part 1 Learning objective: review the anatomy of the male genital tract in relation to its function in reproduction. The male reproductive system: This consists of: External genitalia: penis and scrotum. Internal genitalia: testes, epididymis, vas deferens, ejaculatory duct, seminal vesicle, prostate and bulbourethral glands. Accessory sex glands Endocrine regulation. Testes: Seminiferous tubules arranged in lobules. Sperms originate from the seminiferous tubules. Leydig cells ( interstitial cells ) lie in the loose connective tissue surrounding the seminiferous tubules and secrete testosterone. Enclosed in a capsule called the tunica albuginea. Seminiferous tubules arranged in loops empty into the rete testes. Drain through a dozen vasa efferentia into the head of the epididymis. Epididymis has a head, body and tail. same as Dufferens The tail thickens to become the vas deferens. Cell types in the testes: Inside the seminiferous tubules: germ cells and Sertoli cells. Outside the seminiferous tubules: Leydig cells and peritubular myocytes. Sertoli cells: Large cells that rest on the basement membrane and extend lamentous cytoplasmic rami cations toward the lumen of the tubule. They support and nourish the spermatogenic cells. Secrete Mullerian regression factor. They also release inhibin and activin. They secrete androgen and oestrogen binding proteins. Leydig cells: Found in the interstitium of the testes. Secrete testosterone in response to LH. Two populations: 1. Fetal Leydig cells- secrete testosterone in the fetus and regress after birth. 2. Adult Leydig cells- secrete testosterone from puberty. Blood supply to the testes: Testicular arteries arise from the aorta. Testicular veins ( pampiniform plexus ) drain into renal vein on the left and the IVC on the right. Lymphatic drainage into para-aortic nodes. Scrotal skin drains to inguinal nodes. Epididymis: From rete testes, 12–20, efferent ductules pass into the largest portion of the epididymis known as the head. Efferent ductules enlarge to form lobule- the duct from each lobule drains into a single epididymal duct. Reproductive tracts: Sperm exit each testes through the epididymis, ductus ( vas ) deferens and the ejaculatory duct. The ejaculatory duct drains into a single urethra. The urethra is a common conduit for both urine and semen. Vas deferens: Arises from the tail of the epididymis. Passes through the inguinal canal. At the internal ring it diverges from testicular vessels, passes medially to all structures of the pelvic side wall to the base of the prostate posteriorly. Terminal vas is dilated and is capable of storing spermatozoa. The terminal vas joins the seminal vesicle duct to form the ejaculatory duct that opens into the urethra. Ejaculatory ducts: Creates when the seminal vesicle duct merges with the vas deferens. Travel through the prostate and drain into the colliculus seminalis/ verumontanum of the prostate. Seminal vesicles: Lined with columnar secretory epithelium with goblet cells. Secreted mucoid material containing: fructose, citric acid, prostaglandins and brinogen. During emission and ejaculation, each vesicle empties its contents into the ejaculatory duct shortly after the vas deferens empties the sperm. Seminal vesicle and ampulla of the vas lie posteriorly to the bladder. Ureter enters the bladder medial to the tip of the seminal vesicle. As the vesicles join to form the ejaculatory duct, their smooth muscle coats fuse with a prostatic capsule at its base. Denonvillier’s fascia or, occasionally, the rectovesical pouch of peritoneum separates these structures from the rectum. In normal people, these structures are not palpable on rectal examination. Prostate: Fibromuscular gland situated beneath the bladder. Approx 70% glandular elements and 30% bromuscular stroma. PSA ( prostate speci c antigen ) is one of several serine proteases secreted by the prostate in high concentrations into the ejaculate. The main function relates to regulation of semen coagulation, and it is a valuable marker for prostate disease states. The glandular elements of the prostate have been divided into discrete zones: 1. Transition. 2. Central. 3. Peripheral. Transition zone of the prostate: Gives rise to BPH ( benign prostatic hyperplasia ). A bromuscular band separates this zone from the rest of the prostate. Peripheral zone of the prostate: This makes up the bulk of the prostatic glandular tissue. It covers the posterior and lateral aspects of the gland. Its ducts drain into the prostatic sinus along the entire length of the prostatic urethra. Bulbourethral glands: These are a pair of pea shaped exocrine glands. Located posterolateral to the membranous urethra. They contribute to the nal volume of semen by producing a lubricating mucus.