Reproductive and Genitourinary System PDF

Vas Deferens Arises from epididymal tubules Has similar epithelial lining but a thicker muscular wall Course ○ Passes deep to the scrotal skin through the inguinal canal (as part of the spermatic cord) ○ Joins with the duct from the seminal vesicle to form the ejaculatory duct whi...

Vas Deferens Arises from epididymal tubules Has similar epithelial lining but a thicker muscular wall Course ○ Passes deep to the scrotal skin through the inguinal canal (as part of the spermatic cord) ○ Joins with the duct from the seminal vesicle to form the ejaculatory duct which opens into the prostatic urethra Layers ○ Lumen is lined with mucosa consisting of a lamina propria together with secretory pseudostratified columnar epithelium with apical stereocilia (for absorption of debris) Stellate mucosa ○ Muscle is arranged into 3 layers Inner layer = longitudinal smooth muscle Middle layer = circular smooth muscle Outer layer = longitudinal smooth muscle Functions ○ Contractile - move sperm through the ejaculatory duct past the prostate gland. Thicker muscle ○ Absorbent - can absorb sperm Seminal Vesicles Paired glands of the male pelvis which produce the majority of constituents of semen Structure Located between the fundus of the bladder and rectum The vas deferens combines with the ducts of the seminal vesicles to form the ejaculatory duct → drains into the prostatic urethra Neurovasculature Innervated sympathetically Inferior vesical, internal pudendal and middle rectal artery Seminal Vesicles Pseudostratified columnar epithelium The left and right vas deferens join with the duct emerging from the left and right seminal vesicles ○ During ejaculation, the seminal vesicle contract to flush sperm from the vas deferens into the prostatic urethra Characteristics of seminal vesicles ○ Paired glands ○ Convoluted sacs with highly folded pseudostratified columnar epithelium ○ Thin layer of smooth muscle ○ Androgen dependent ○ Secrete white-yellow viscous fluid containing fructose, sugars and ascorbic acid (seminal fluid). This combines with prostatic secretions to form ejaculate Prostate Gland Walnut-shaped gland inferior to the bladder and superior to the external urethral sphincter Can be divided into either lobes and zones ○ The median lobe is more commonly enlarged in benign prostatic hyperplasia Functions (secretory) ○ Citric acid - nourishment ○ Seminal plasmin - antibiotic properties for combatting UTIs ○ PSA (prostate specific antigen) - liquefies semen after ejaculation Used to screen for prostate cancer Commonly enlarges with ageing Prostatic part of the urethra cross through the prostate Prostate Gland Zones (3) Central zone = surrounds ejaculatory ducts (25% of prostate volume) Transitional zone = surrounds urethra (5-10% of prostate volume) ○ These gland typically undergo BPH Peripheral zone = body of the gland and located posteriorly (65%) Fibromuscular stroma (4th zone) = situated anteriorly and merges with tissue of the urogenital diaphragm and muscular precursor to urethral sphincters Vasculature Arterial supply = prostatic arteries (internal iliac arteries) Venous drainage = prostatic venous plexus (internal iliac veins) ○ Also connects to Batson venous plexus (internal vertebral venous plexus) Innervation = inferior hypogastric plexus (SNS, PNS and sensory) ○ Prostate is flanked by neurovascular bundles which supply the penis for erections - may be damaged in radical prostatectomy Prostate Gland Largest accessory gland Heterogeneous epithelium - composed of cuboidal, columnar and pseudostratified epithelium Testosterone stimulates growth of the prostate Secretes zinc, citric acid, prostaglandins, PSA and proteolytic enzymes Characteristics ○ Urethra (prostatic urethra) runs through it ○ Tubuloalveolar glands appear in zones Outer zone is susceptible to inflammation and cancer Zone around the urethra often enlarges Bulbourethral Glands Also known as Cowper’s glands, situated posterolateral to the membranous urethra Produce lubricating mucus which contributes to final volume of semen Contains tubuloalveolar glands lined by columnar epithelium Open into the proximal portion of the spongy urethra