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Male Reproductive System th 2298426b@student.gla.ac.ukGross Anatomy • Fibromuscular cutaneous sac lying posterior to the penis and anterior to the anus The Scrotum • Contains three paired structures: • Testes • Epididymis • Spermatic cord • Some damn Englishmen call it testes • Dartos muscle • Smooth muscle • Contracts in response to cold temperatures • Cremasteric muscle • Skeletal muscle • Responsible for the cremasteric reflexGross AnatomyThe T estes • Paired structures located within the scrotum, suspended by the spermatic cord • Two main functions: • Exocrine: spermatogenesis • Endocrine: testosterone • Covered by the tunica vaginalis, which is a closed sac of peritoneumThe ductules T estes • Extensive system of ducts, beginning with the seminiferous tubules and ending in the epididymis • Seminiferous tubules are highly coiled and arranged into lobules Rete testis • The parenchyma (i.e., the tubules) are protected by a fibrous capsule called the tunica albuginea Straight tubulesThe TestesThe • Spermatogonia T estes • Immature spermatogonia adjacent to the basement membrane • Spermatogonia > spermatocytes > spermatids • Sertoli cells • Triangular nuclei near the basement membrane • Large cytoplasm that expands across the tubule (not visible with an H&E stain) • Responds to FSH • Protective and secretory functions • Formation of very strong tight junctions to protect newly formed spermatids from the immune system • Secretion of anti-Mullerian hormone, inhibin, androgen-binding protein, and oestrogen macrophagesThe T estes • Leydig cells (interstitial cells) • Produce testosterone in response to LH • Peritubular myoid cells • Smooth muscle cells lining the periphery of the seminiferous tubule • Function not entirely understood • Thought to play a role in transport of spermatids along the seminiferous tubuleThe Epididymis • Located on the posterior surface of the testes • A single, heavily coiled duct lined with pseudostratified ciliated columnar epithelium • Divided into a head, body, and tail • deferens is continuous with the ductus • Responsible for storage and continued maturation of spermatidsGross AnatomyDuctus Deferens • Continuation of the epididymis • Approximately 45cm long • Thick smooth muscle wall with narrow lumen • Passes through the inguinal canal, turns medially at the base of the bladder, and joins with the duct of the seminal gland to form the ejaculatory ductThe Spermatic Cord • Formed at the opening of the inguinal canal (deep inguinal ring) • Passes through the inguinal canal and into the scrotum, where its contents disperse • Contents held together by three layers: external spermatic fascia, cremaster muscle, and internal spermatic fasciaThe Spermatic Cord • Three arteries: • Cremasteric • Testicular • Artery of the ductus deferens • Three nerves: • Genital branch of the femoral nerve • Cremasteric nerve • Sympathetic nerve fibres • Three other things: • Ductus deferens • Pampiniform plexus (veins) • LymphaticsGross AnatomySeminal Vesicles • Paired glands located between the bladder Seminal Glands/Vesicular Glands fundus and rectum • Combine with the vas deferens to form the ejaculatory duct • Coiled tubes lined by pseudostratified columnar epithelium • Secretions form 70% of the volume of semen • Alkaline fluid • Fructose • Prostaglandins • Clotting factorsProstate Gland • Roughly the size of a walnut • Comprised of glandular tissue and fibromuscular stroma • Produces slightly alkaline fluid containing: • Citrate, which is used by sperm for ATP production • Phosphate and proteolytic enzymes, which liquify the coagulated semen • Pea-shaped exocrine glands posterolateral Cowper’s Glandslands to the membranous urethra • Lined with columnar epithelium • Produces a mucus secretion containing glycoproteins during sexual arousal (aka pre-ejaculate) • Lubrication of the penis and urethra • Removes residual urine from the urethra to provide a clean, lubricated route • Alkaline fluid to neutralise the acidic vaginaGross AnatomyThe Penis • Two main functions: sexual intercourse/ejaculation and micturition • Divided into three parts: • Root: not visible externally; located in the superficial perineal pouch • Body: suspended from the pubic symphysis • Glans: conical shaped distal part of the penis formed by the corpus spongiosum; contains the opening of the urethraThe Penis • Erectile tissues fill with blood during sexual arousal • The left and right crura (root) continue anteriorly to form the two corpus cavernosa • The corpus cavernosa consist of large blood sinuses, which fill during erection • The bulb (root) continues anteriorly to form the corpus spongiosum • Contains the urethra • Fills to a lower pressure to prevent compression of the urethraArterial Supply Scrotum Cremasteric (External Iliac) External pudendal (External Iliac) Testes Testicular artery (Aorta) Cremasteric artery (External Iliac) Artery to the vas deferens (Internal Iliac) Seminal Vesicles Inferior vesical artery (Internal & Prostate Iliac) Middle rectal artery (Internal Iliac) Penis Internal pudendal artery (Internal Iliac)Venous Drainage Scrotum Scrotal veins > external iliac veins Testes Pampiniform plexus > testicular veins Seminal Vesicles Inferior vesical artery (Internal Iliac) Middle rectal artery (Internal Iliac) Prostate Prostatic venous plexus > internal iliac vein Penis Prostatic venous plexus > internal iliac veinMale Reproductive System th 2298426b@student.gla.ac.uk