Male Internal Genitalia Overview

Study Notes

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.

Description

This quiz explores the male internal genitalia, detailing the functions and anatomical features of organs such as the testes, epididymis, and prostate. Understand the role of these organs in hormone production and reproductive health.