Male Reproductive System

Male Reproductive System

• Consists of: testes, epididymis, deferent ducts, accessory glands, and penis

Testes

• Responsible for producing spermatozoa and synthesizing testosterone
• Protected by scrotum (exorchid species) and testicular tunics (tunica vaginalis and tunica albuginea)
• Scrotum is a bag-like structure containing the testicles, composed of three layers: skin, tunica dartos, and scrotal fascia

Testicular Tunics

• Tunica vaginalis: a connective tissue layer covered by mesothelium, comes in two continuous sheets (parietal and visceral layers)
• Tunica albuginea: a thick and solid capsule made of connective tissue, predominantly collagen, elastic arteries, and myofibroblasts

Interstitium

• Spaces between seminiferous tubules, consisting of loose connective tissue with blood vessels, lymph vessels, and free mononuclear cells
• Testosterone production by interstitial (Leydig) cells

Leydig Cells

• Found in clusters at the interstitium, responsible for ~90% of testosterone production
• Large polymorphic cells with round and centrally located nuclei, exhibiting mitochondria with tubular cisterna
• Two generations of interstitial Leydig cells: fetal and puberal

Seminiferous Tubules

• Highly coiled, tightly packed tubules where spermatozoa are produced by spermatogenesis
• Stratified spermatogenic epithelium, bordered externally by a layer of contractile myoepithelial cells
• Sertoli cells provide support, nourishment, and protection to developing spermatozoa

Sertoli Cells

• Also known as sustentacular or supportive cells
• Secrete AMH during embryonic development, suppressing female tubular genitalia in the male
• Necessary for spermatogenesis, responding to FSH and testosterone
• Form the blood-testis barrier, with minimal production of steroid hormones

Spermatozoa

• Elongated, motile male gametes found in close association with Sertoli cells
• Structure: head, neck, middle piece, and tail
• The middle piece contains a mitochondrial sheath that provides energy for sperm mobility

Straight Testicular Tubules

• Seminiferous tubules terminate at the straight testicular tubules, connected to the rete testis
• Lined by simple squamous to columnar epithelium (Sertoli cells), with no spermatogenesis taking place
• Macrophages are present, eliminating slow or non-motile spermatozoa

Epididymis

• A complex network of tubules connecting the testis (rete testis) to the vas deferens
• Macroscopically: head, body, and tail
• Histology: lined by pseudostratified columnar epithelium, with tall columns and stereocilia
• Functions: maturation and storage of spermatozoa, absorption of fluid, and secretion of metabolically active substances

Pampiniform Plexus

• Serves primarily to facilitate heat exchange, promoting diffusion of gases, low-molecular weight substances, and lipid-soluble substances

Vas Deferens

• Terminating at the colliculus seminalis of the proximal urethra
• Lined by a folded mucosa with ciliated pseudostratified columnar epithelium
• Histology: thick muscular wall with circular fibers predominating

Accessory Glands

• Primary function: producing serous or mucous secretions that nourish, transport, and activate spermatozoa, and protect spermatozoa by neutralizing acid urine
• Species variations: ampulla, prostate gland, vesicular glands, and bulbourethral glands

Prostate Gland

• Strong androgen dependence, atrophying with castration
• Lined by a thick fibromuscular capsule/trabecula, with secretory units (acini) lined by simple/stratified columnar epithelium
• Predominately a serous secretion

Penis

• Consists of two dorsal masses of erectile tissue (corpora cavernosa) and a ventral mass (corpora spongiosum)
• Histology: bound together by a fibroelastic layer (tunica albuginea), creating trabeculae
• Erectile tissue contains numerous vascular spaces (cavernous spaces) that are surrounded by smooth muscle layer, filled with blood during erection

Male Reproductive System

• Consists of: testes, epididymis, deferent ducts, accessory glands, and penis

Testes

• Responsible for producing spermatozoa and synthesizing testosterone
• Protected by scrotum (exorchid species) and testicular tunics (tunica vaginalis and tunica albuginea)
• Scrotum is a bag-like structure containing the testicles, composed of three layers: skin, tunica dartos, and scrotal fascia

Testicular Tunics

• Tunica vaginalis: a connective tissue layer covered by mesothelium, comes in two continuous sheets (parietal and visceral layers)
• Tunica albuginea: a thick and solid capsule made of connective tissue, predominantly collagen, elastic arteries, and myofibroblasts

Interstitium

• Spaces between seminiferous tubules, consisting of loose connective tissue with blood vessels, lymph vessels, and free mononuclear cells
• Testosterone production by interstitial (Leydig) cells

Leydig Cells

• Found in clusters at the interstitium, responsible for ~90% of testosterone production
• Large polymorphic cells with round and centrally located nuclei, exhibiting mitochondria with tubular cisterna
• Two generations of interstitial Leydig cells: fetal and puberal

Seminiferous Tubules

• Highly coiled, tightly packed tubules where spermatozoa are produced by spermatogenesis
• Stratified spermatogenic epithelium, bordered externally by a layer of contractile myoepithelial cells
• Sertoli cells provide support, nourishment, and protection to developing spermatozoa

Sertoli Cells

• Also known as sustentacular or supportive cells
• Secrete AMH during embryonic development, suppressing female tubular genitalia in the male
• Necessary for spermatogenesis, responding to FSH and testosterone
• Form the blood-testis barrier, with minimal production of steroid hormones

Spermatozoa

• Elongated, motile male gametes found in close association with Sertoli cells
• Structure: head, neck, middle piece, and tail
• The middle piece contains a mitochondrial sheath that provides energy for sperm mobility

Straight Testicular Tubules

• Seminiferous tubules terminate at the straight testicular tubules, connected to the rete testis
• Lined by simple squamous to columnar epithelium (Sertoli cells), with no spermatogenesis taking place
• Macrophages are present, eliminating slow or non-motile spermatozoa

Epididymis

• A complex network of tubules connecting the testis (rete testis) to the vas deferens
• Macroscopically: head, body, and tail
• Histology: lined by pseudostratified columnar epithelium, with tall columns and stereocilia
• Functions: maturation and storage of spermatozoa, absorption of fluid, and secretion of metabolically active substances

Pampiniform Plexus

• Serves primarily to facilitate heat exchange, promoting diffusion of gases, low-molecular weight substances, and lipid-soluble substances

Vas Deferens

• Terminating at the colliculus seminalis of the proximal urethra
• Lined by a folded mucosa with ciliated pseudostratified columnar epithelium
• Histology: thick muscular wall with circular fibers predominating

Accessory Glands

• Primary function: producing serous or mucous secretions that nourish, transport, and activate spermatozoa, and protect spermatozoa by neutralizing acid urine
• Species variations: ampulla, prostate gland, vesicular glands, and bulbourethral glands

Prostate Gland

• Strong androgen dependence, atrophying with castration
• Lined by a thick fibromuscular capsule/trabecula, with secretory units (acini) lined by simple/stratified columnar epithelium
• Predominately a serous secretion

Penis

• Consists of two dorsal masses of erectile tissue (corpora cavernosa) and a ventral mass (corpora spongiosum)
• Histology: bound together by a fibroelastic layer (tunica albuginea), creating trabeculae
• Erectile tissue contains numerous vascular spaces (cavernous spaces) that are surrounded by smooth muscle layer, filled with blood during erection

Male Reproductive System

• Consists of: testes, epididymis, deferent ducts, accessory glands, and penis

Testes

• Responsible for producing spermatozoa and synthesizing testosterone
• Protected by scrotum (exorchid species) and testicular tunics (tunica vaginalis and tunica albuginea)
• Scrotum is a bag-like structure containing the testicles, composed of three layers: skin, tunica dartos, and scrotal fascia

Testicular Tunics

• Tunica vaginalis: a connective tissue layer covered by mesothelium, comes in two continuous sheets (parietal and visceral layers)
• Tunica albuginea: a thick and solid capsule made of connective tissue, predominantly collagen, elastic arteries, and myofibroblasts

Interstitium

• Spaces between seminiferous tubules, consisting of loose connective tissue with blood vessels, lymph vessels, and free mononuclear cells
• Testosterone production by interstitial (Leydig) cells

Leydig Cells

• Found in clusters at the interstitium, responsible for ~90% of testosterone production
• Large polymorphic cells with round and centrally located nuclei, exhibiting mitochondria with tubular cisterna
• Two generations of interstitial Leydig cells: fetal and puberal

Seminiferous Tubules

• Highly coiled, tightly packed tubules where spermatozoa are produced by spermatogenesis
• Stratified spermatogenic epithelium, bordered externally by a layer of contractile myoepithelial cells
• Sertoli cells provide support, nourishment, and protection to developing spermatozoa

Sertoli Cells

• Also known as sustentacular or supportive cells
• Secrete AMH during embryonic development, suppressing female tubular genitalia in the male
• Necessary for spermatogenesis, responding to FSH and testosterone
• Form the blood-testis barrier, with minimal production of steroid hormones

Spermatozoa

• Elongated, motile male gametes found in close association with Sertoli cells
• Structure: head, neck, middle piece, and tail
• The middle piece contains a mitochondrial sheath that provides energy for sperm mobility

Straight Testicular Tubules

• Seminiferous tubules terminate at the straight testicular tubules, connected to the rete testis
• Lined by simple squamous to columnar epithelium (Sertoli cells), with no spermatogenesis taking place
• Macrophages are present, eliminating slow or non-motile spermatozoa

Epididymis

• A complex network of tubules connecting the testis (rete testis) to the vas deferens
• Macroscopically: head, body, and tail
• Histology: lined by pseudostratified columnar epithelium, with tall columns and stereocilia
• Functions: maturation and storage of spermatozoa, absorption of fluid, and secretion of metabolically active substances

Pampiniform Plexus

• Serves primarily to facilitate heat exchange, promoting diffusion of gases, low-molecular weight substances, and lipid-soluble substances

Vas Deferens

• Terminating at the colliculus seminalis of the proximal urethra
• Lined by a folded mucosa with ciliated pseudostratified columnar epithelium
• Histology: thick muscular wall with circular fibers predominating

Accessory Glands

• Primary function: producing serous or mucous secretions that nourish, transport, and activate spermatozoa, and protect spermatozoa by neutralizing acid urine
• Species variations: ampulla, prostate gland, vesicular glands, and bulbourethral glands

Prostate Gland

• Strong androgen dependence, atrophying with castration
• Lined by a thick fibromuscular capsule/trabecula, with secretory units (acini) lined by simple/stratified columnar epithelium
• Predominately a serous secretion

Penis

• Consists of two dorsal masses of erectile tissue (corpora cavernosa) and a ventral mass (corpora spongiosum)
• Histology: bound together by a fibroelastic layer (tunica albuginea), creating trabeculae
• Erectile tissue contains numerous vascular spaces (cavernous spaces) that are surrounded by smooth muscle layer, filled with blood during erection

Learn about the components and functions of the male reproductive system, including testes, epididymis, and accessory glands.