Male Reproductive Anatomy.docx

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Western University
Anatomy and Cell Biology
Anatomy and Cell Biology 3319
Kem Rogers

Male Reproductive Anatomy Reproductive Structures • Primary sex organs o Gonads (testes)  Form spermatozoa  Secrete sex hormones (androgens – testosterone) • Secondary sex organs o Needed for transmission of sperm o Ducts  Epididymis  Ductus (vas) deferens (carry sperm from testes to ejaculatory duct)  Ejaculatory duct  Urethra (runs through of the prostate gland) o Accessory glands  Seminal vesicles  Prostate glands  Bulbourethral gland o Copulatory organ – penis Scrotum • Sac of skin & superficial fascia that hangs inferiorly external to abdominopelvic cavity at root of penis • Contain muscle and connective tissue and is covered by skin • Supports, protects and regulates the position of testes • Maintain testes at 3°C below body temperature o Muscle will regulate position for temperature changes  Cold: draw testes towards body, skin wrinkles to increase thickness & reduce heat loss  Warm: muscles relax, so skin is flaccid & loose & testes hang low to increase skin surface available for cooling (sweating) o Actions are performed by two muscles  Dartos muscle: layer of smooth muscle in superficial fascia, is responsible for wrinkling the scrotal skin  Cremaster muscles: bands of skeletal muscle that extend inferiorly from the internal oblique muscle of the trunk, are responsible for elevating the testes • Coverings are continuous with fascia of the spermatic cord o Rich blood supply – testicular artery, & venous drainage o Nerves o Vas deferens • Fused during development – single structure with septum dividing scrotum into right & left halves - one compartment for each testis o Superficial fascia – contains dartos muscle and skin (thick and wrinkly) Descent of Testes • Development begins near kidneys - arteries that supply gonads come off close to area of renal arteries • During development (2 months) both the developing kidneys and gonads start developing in a similar area (retroperitoneal: near posterior abdominal wall) • Gubernaculum o Long cord like structure – goes from gonad that goes down to scrotum swelling o Pull testes down to where they finally reside o Shortens/constricts and pull testes down o Females have one – pull ovaries but stops earlier than testes o In adult – not much left of it o As testes descend – blood supply follows o 7 months  Gubernaculumbegins to shorten which pulls testis down and forward (in front of pubic bone)  Drags parietal peritoneum along with it – vaginal process o 8 months  Inguinal canal begins to develop  Vaginal process continues to be pulled down into scrotal swelling  Testes also get pulled down into scrotal swelling past the pubic bone  Vaginal process slightly goes around testes  Scrotal swellings enlarge o 1 month old  Area where perotineum came through will seal of - vaginal process becomes sealed  Tunica vaginalis • Remains as remnant of vaginal process  Testis fully descended into scrotum  Testis accompanied by testicular artery, vein & nerve  Descent begins in weeks 6-10 and is finished by week 28  3% of boys are born with undescended testes - testes will eventually descend  Little gubernaculum Testes • Approximately 4 cm X 2.5 cm • Surrounded by two tunic layers o Tunica vaginalis o Double-layered that arose from peritoneum o Will have visceral and parietal layer o Covers some of the tubules that leave the testes (epididymis) o Potential space between visceral and parietal layers – can fill with fluid and cause issues  Hydrocele with fluid (lymphatic fluid)  Hematocele with blood o Tunica albuginea o Thick fibrous capsule tightly adhered to testes o Whitish appearance o Septa dividing testis into 250-300 lobules o Within each lobule you have 4-5 seminiferous tubules  Where stem cells for sperm reside – in walls  As they mature they move towards centre  Tubes converge down to fewer and fewer tubes  Converge on Rete testes  From rete testes form epididymis o Epididymis then converge into a single tube (vas deferens) which leave via spermatic cord Clinical Correlate: Hydrocele and Hematocele • Hydrocele o Accumulation of fluid within the tunica vaginalis o ECF can accumulate o Problem with lymphatic drainage • Hematocele o Accumulation of blood within tunica vaginalis (and surrounding tissues) usually due to trauma o Ruptured blood vessels can lead to hematocele o Blood is trapped o Pathway has been fused off so the blood continues to accumulate Inguinal Canal • Where spermatic cord passes through to get to testes o Fibrous cord o Contains vas deferens, testicular artery, venous drainage & testicular nerve • As the rest of the structures develop around the descended testes – they go around the spermatic cord • Mo st of the coverings come from the abdominal wall o Most external layer: external oblique  End in aponeurosis and will form the anterior part of inguinal canal o Next layer: internal oblique  Ends in aponeurosis and will form the posterior wall and roof of inguinal canal o Next layer: transverses abdominus  Form posterior wall of the inguinal canal o Floor of canal is formed by inguinal ligament o Deep Ring  Opening through inguinal canal wall through which spermatic cord travels o Superficial ring  Point at which it emerges to go to testes • Inguinal canal formed as testis move through abdominal wall • As testis descend through abdominal wall, pushes through abdominal wall layers • Layers of abdominal wall become layers in scrotum o External oblique  external spermatic fascia (not muscle  goes through aponeurosis) o Internal oblique  cremaster muscle/fascia (still muscle  draws testes up) o Transversalis fascia  internal spermatic fascia o Parietal peritoneum  tunica vaginalis Clinical Correlate: Vasectomy • All converge to single tubule which passes through the spermatic cord  Vas Deferens • During ejaculation, the muscle contracts and pushes sperm into ejaculatory duct • Vasectomy o Incision into scrotum and snip the vas deferens so that spermatozoa have no connection to outside o Spermatazoa still being produced but no way out so will be phagocytized by macrophages o Can reconnect tube (50% success rate) Clinical Correlate: Inguinal Hernia • Small intestine or omentum protrudes through a weakness in abdominal wall – follows inguinal canal • Omentum or intestine can slip through into the testes - can end up within the inguinal canal or upper part of scrotum or can go into lower part of the scrotum • Often precipitated by lifting or straining which increases intraabdominal pressure – painful • Loop can become twisted and blood supply is cut off and then that part of the intestine will die and become gangrenous • Increased pressure, then herniated part of intestine will get forced through potential part of intestine • Surgical repair involves placing a mesh patch over weakened area • Less apparent in females – no spermatic cord • Femoral hernia is common in women Indirect Inguinal Hernia • When loop will follow the pathway of the inguinal canal • Enter through deep ring and slide through superficial ring  to deeper part of scrotum • Congenital condition – improper fusing (normally no direct opening) • Epigastric vessel o Supply rectus abdominus o If bulge is lateral, then indirect hernia o If bulge is medial then direct hernia Direct Inguinal Hernia • Abdominal content go through weakening of abdominal wall • Overweight patients or patients with weak abdominal wall • Protrusion of abdominal content • Forms in upper part of the scrotum Spermatic Cord • Vas Deferens o Going through the inguinal canal • Testicular Artery o From the aorta near the renal arteries o Goes through inguinal canal • Autonomic nerve fibers (SNS and PNS) o SNS nerves supply the smooth muscle of vas deferens and part of the dartos muscle o PNS - nerves to the cremaster muscle (to draw testes up) • Venous drainage o Not just straigh
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