Male Reproductive System

Cards (31)

  • Parts of the male reproductive system

    • Testis
    • Epididymis
    • Ductus deferens
    • Accessory glands
    • Penis
  • Functions of the male reproductive system

    • Produce sperm
    • Store and transport the sperm
    • Produce seminal fluid
    • Ejaculate
    • Secrete testosterone
  • Testis
    Organ to produce sperm and testosterone
  • Testis
    • Made of seminiferous tubules
  • Epididymis
    Accumulation, storage & maturation of spermatozoa
  • Epididymis
    • Head, body, tail
    • Continuous to the ductus deferens which enters the pelvic cavity
  • Sperm transfer

    Seminiferous tubules -> epididymis -> Vas deferens
  • Testes - Gross Anatomy (dog)

    • Sacrotuberous ligament
    • Caudal gluteal vessels
    • Internal pudendal vessels
    • Anus
    • Pelvic urethra
    • Bulb of penis enclosed by bulbospongiosus
    • Ischiocavernosus over left crus
    • Body of penis
    • And 9' = bulbus and pars longa glandis
    • Spermatic cord, ductus deferens, cremaster muscle
    • Testes in scrotums
    • Dorsal artery and vein of the penis
    • Femoral vessels
  • Accessory sex glands

    • Seminal vesicles (=vesicular gland)
    • Prostate gland (main)
    • Bulbourethral (Cowper's) gland
  • Accessory sex glands

    Add nutrients and may contribute the final volume of the seminal fluid (not all present in every species)
  • Ampulla of Ductus Deferens

    Drains sperm to the urethra
  • Penis
    • Rigidity = tumescence (swelling)
    • Mammalian penis engorged with blood
    • Avian phallus engorges with lymph
    • Os penis in some species
    • Muscular contractions -> muscles massage the urethra to move sperm
  • Prepuce
    • Skin sheath concealing penis in quiescent state
    • Formed from abdominal skin
    • Stallions (uncastrated male horse) have an extra fold
  • Anatomy of the Penis
    • 3 columns of erectile tissue
    • Corpus Cavernosum x2
    • Corpus Spongiosum
    • Penis divided anatomically into: Root, Body, Free part
  • Corpus Cavernosum Penis (CCP)

    • Paired, start at crus (pl. Crura)
    • Dorsal to urethra
    • Enclosed in tunica albuguinea
  • Types of Corpus Cavernosum Penis

    • Fibroelastic = boar and ruminant
    • Musculocavernous = stallion, man, and dog (atypical)
  • Fibroelastic Corpus Cavernosum Penis
    • Small cavernous spaces divided by tough fibroelastic tissue
    • Less blood is required for erection
    • Sigmoid flexure at the body of penis – allows extrusion at coitus
  • Musculocavernous Corpus Cavernosum Penis

    • Larger cavernous spaces divided by muscular tissue
    • More blood required for erection
    • Erection involves significant increase in length & girth
  • Corpus Spongiosum Penis (CSP)

    • Spongy sleeve around urethra
    • Enlarged to form Bulb of penis
    • Expands over the apex of penis to form Glans
    • More delicate than CCP with larger blood spaces
  • Anatomy of the Penis
    • Erectile tissue of CSP and CCP made of numerous cavernous spaces (filled with blood)
    • Cavernous spaces divided by trabeculae
    • Trabecular composed of: Smooth muscle, Fibroblasts, Collagen, Elastic fibres, Endothelial cells
  • Species Differences in Penis

    • Dog & cat distal part of CCP bone = os penis
    • Glands penis different
  • Ischiocavernosus muscle

    • Originate ischial arches and enclose around crura till their fusion
    • Compress the crus part of corpus cavernosum against the ischium thus occluding veins and preventing venous return from CCP
  • Bulbospongiosus muscle

    • Surround the corpus spongiosum
    • Covers the root of the penis ventral to CSP
    • Continuation of urethralis muscle
    • Empties extrapelvic urethra of sperm
    • Circular striated muscle
  • Refractor penis muscle

    • Paired
    • Originates caudal vertebrae down perineum around anal canal to ventral penis
    • Retracts penis
    • Smooth muscle
  • Arterial supply of Penis
    • External (to skin) and internal (to CCP, CSP) pudendal arteries
  • Venous Draining of Penis
    • CCP: Supply - root of penis, Drainage - root of penis
    • CSP: Supply - bulb of penis, Drainage - from distal part of penis
  • Erection, intromission, and ejaculation

    1. Vascular, neurological and endocrine systems work together
    2. Erection: contraction of the ischiocavernosus muscle -> occlusion of venous outflow
    3. Relaxation of corpus cavernosum and corpus spongiosum via parasympathetic nerve
    4. Intromission: mounting behaviour
    5. Emission: release of spermatozoa and accessory gland fluids into the pelvic urethra
    6. Ejaculation: forceful expulsion of semen from the urethra
    7. Post-ejaculation: increase in the smooth muscle tone of the cavernous space -> increase of outflow of blood, contraction of the refractor penis muscle withdraws the penis into the prepuce
  • Male reproductive endocrine axis

    Gonadotropin-Releasing Hormone (GnRH) -> FSH, LH -> Leydig cells, Sertoli cells -> Testosterone, inhibin
  • Descend of testes in embryos

    1. Gonad develops retroperitoneally
    2. Sperm cannot develop at core body temp
    3. Gubernaculum is a ligament connecting the gonad to the future scrotum via inguinal canal and 'pulls down' the gonad
    4. While descending, testes push all layers of the abdominal wall
    5. A part of the peritoneum also descends together and forms tunica vaginalis (vaginal tunic)
  • Testicular Descent

    • Testes descend through inguinal canal to scrotum usually before birth
    • Failed descent prevents sperm production & can cause neoplasia
  • Open or closed castration

    • = open or does not open the vaginal tunic
    • = cut the layers of [internal spermatic fascia and parietal vaginal tunic] or not