Male Reproductive System Overview

Male Reproductive System

• The male reproductive system is divided into three parts: the testis, the excretory ducts, and accessory glands.

Testes

• Paired ovoid organs.

• Produce male gametes (spermatozoa) and testosterone.

• Found outside the major body cavity, housed in the scrotum.

• Composed of:

  • Stroma: Surrounded by a thick capsule (tunica albuginea) with a layer of outer connective tissue (tunica vaginalis). Septa divide the testis into lobules.
  • Parenchyma: Consist of seminiferous tubules (within lobules) where spermatogenesis takes place, and interstitial tissue (Leydig cells) producing testosterone.

• Seminiferous tubules:

  • Contained within each lobule.
  • Enclosed by a thick basal lamina and surrounded by smooth muscle cells (myoid cells).
  • Lined with seminiferous epithelium with two cell types:
    • Spermatogenic cells (spermatogonia): Develop into sperm and include different maturation stages of spermatozoa.
    • Sertoli cells: Support, nourish, and provide hormonal receptors for germ cells.

• Leydig cells: Produce testosterone.

Excretory Duct System

• Rete Testis: Network of tubules within the mediastinum of the testis.
• Efferent Ducts: Passageways from the testis to the epididymis (15-30 ducts).
• Epididymis: Single, long coiled duct (~6 meters) with three parts (head, body, and tail). Lined with pseudostratified columnar epithelium with stereocilia. Maturation and storage of sperm occurs in the epididymis. Sperm stored in the tail of the epididymis.
• Vas Deferens (Ductus Deferens): Straight tube continuing from the tail of epididymis to the prostatic urethra. Lined with pseudostratified columnar epithelium with stereocilia. High muscle-to-lumen ratio. Transports sperm from the epididymal tail.

Accessory Glands

• Seminal Vesicles: Pair of convoluted tubular glands behind the urinary bladder. Their mucous membrane forms folds with secretory pseudostratified columnar epithelium. Secrete 60% of semen, including fructose, proteins, prostaglandins, and mucus.
• Prostate Gland: Single gland at the base of the urinary bladder, surrounding the urethra. Formed of dense fibromuscular connective tissue (stroma). Consists of 30-50 tubulo-alveolar glands with irregular secretory alveoli and papillary projections. Lumen lined with cuboidal, columnar, or pseudostratified columnar epithelium. Secretes components of seminal fluid. Contains granules and secretions including citric acid, fibrinolysin, and other enzymes and lipids. Corpora amylacea are a characteristic feature. Semen passes through prostatic and penile urethra. Benign prostatic hyperplasia (BPH) is a common condition affecting older men.
• Bulbourethral Glands (Cowper's glands): Small glands located below the prostate gland.

Spermatogenesis

• Process of sperm production.
• Occurs in the seminiferous tubules.
• Series of stages: spermatogonia, primary spermatocytes, secondary spermatocytes, spermatids, and spermatozoa.
• Meiosis I and II separate the chromosomes.
• Approximately 48 days for maturity.
• FSH regulates spermatogenesis.

Penis

• Consists of 3 cylindrical masses of erectile tissue: two corpora cavernosa and one corpus spongiosum (surrounding the urethra).
• Erectile tissue composed of connective tissue, smooth muscle, and blood spaces separated by connective tissue.
• Externally surrounded by skin.