Male Internal Genitalia Overview

Male Internal Genitalia

• Male internal genital organs consist of the testes, epididymis, ductus deferens, seminal glands, ejaculatory ducts, prostate, and bulbo-urethral glands.
• Testes function as male gonads, producing sperm and hormones, primarily testosterone.
• Size of the testes averages approximately 5 cm in length, 3 cm in anterior-posterior diameter, and 2.5 cm in thickness.
• Testes are suspended within the scrotum by the spermatic cord for temperature regulation.

Testis Structure

• Externally, the testes have two poles (upper and lower), two borders (anterior and posterior), and two surfaces (medial and lateral).
• Covered by multiple layers including:
  • Tunica vaginalis: comprises visceral and parietal layers.
  • Tunica albuginea: fibrous capsule enclosing the testis.
  • Tunica vasculosa: vascular layer.
• Internally, contains around 200-300 lobules, each featuring coiled seminiferous tubules for sperm production.

Ductus Deferens

• Known as the vas deferens; a muscular tube about 45 cm long.
• Transports sperm from epididymis to ejaculatory duct.
• Originates from the tail of the epididymis, ascends in the spermatic cord, passes through the inguinal canal, and enters the pelvis.
• Ends by joining the seminal gland duct to form the ejaculatory duct.

Arterial Supply and Venous Drainage

• Arteries supplying the vas deferens include branches from the superior vesical, inferior vesical, and middle rectal arteries.
• Venous drainage merges with the vesical venous plexus, draining into the internal iliac veins.

Nerve Supply

• Innervated by parasympathetic fibers from the pelvic splanchnic nerves.

Epididymis

• An elongated structure on the posterior testis, formed by coiled duct structures.
• Comprises three parts:
  • Head: contains lobules formed by efferent ductules.
  • Body: convoluted duct of the epididymis.
  • Tail: leads to the ductus deferens.
• Highly vascularized by the testicular artery; also features specific venous and lymphatic drainage.

Seminal Glands

• Also referred to as seminal vesicles; typically 5 cm long.
• Located between the bladder and rectum, secreting thick alkaline fluid rich in fructose.
• Contributes to the formation of the ejaculatory duct along with the ductus deferens.
• Blood supply stems from inferior vesical and middle rectal arteries.

Ejaculatory Duct

• Formed by the union of seminal gland ducts and ductus deferens.
• Approximately 2.5 cm in length, running through the posterior part of the prostate.
• Opens into the prostatic urethra near the seminal colliculus, with arterial supply from the inferior vesical artery.

Bulbourethral Glands

• Known as Cowper's glands, located posteriolateral to the intermediate urethra.
• Ducts open into the proximal part of the spongy urethra, assisting in lubrication during ejaculation.

Prostate Gland

• The largest accessory gland in the male reproductive system, averaging 3 cm long, 4 cm wide, and weighing about 30g.
• Situated below the bladder neck and surrounding the prostatic urethra.
• Composed of fibrous (1/4), muscular (1/4), and glandular tissue (1/2).
• Glandular tissue consists of tubuloalveolar glands organized into mucosal, submucosal, and main prostatic glands.

Arterial and Venous Supply

• Supplied by branches from the inferior vesical, middle rectal, and internal pudendal arteries.
• Drains via the prostatic venous plexus into internal iliac veins.
• Lymphatic drainage channels into internal, external iliac, and sacral lymph nodes.

Nerve Supply and Development

• Receives both sympathetic and parasympathetic innervation.
• Glandular development occurs during the third month of intrauterine life, with mesenchymal origins for stroma forming in the fourth month.

Clinical Correlation

• Conditions include benign prostatic hyperplasia (BPH), prostatectomy procedures, and prostatic carcinoma.

Anatomy of the Prostate

• Divided into five lobes: anterior (isthmus), posterior, median, and two lateral lobes.
• Comprised of fibrous, muscular, and glandular tissues with tubuloalveolar glands opening into the urethra.

Additional Structural Features

• Contains corpora amylacea within the gland lumen.
• Anteriorly bordered by the pubic symphysis; posteriorly by the rectum and sacrum.
• The gland possesses an apex and a base, contributing to its overall morphology.