精巣: 組織学

The tunica albuginea, a tough fibrous membrane covering each testis, extends inward to form fibrous partitions called septa testis. These septa divide the testis into internal compartments called lobules. Each lobule contains one to three tightly coiled seminiferous tubules, which are the primary sites for sperm production.

Sertoli cells, also called sustentacular cells, support and nourish spermatogenic cells within the seminiferous epithelium. These cells are interspersed among the developing sperm cells and provide essential nutrients and structural support as spermatogenic cells differentiate into mature spermatozoa progressing toward the tubule's lumen.

Leydig cells, also known as interstitial cells, are located between adjacent seminiferous tubules. These cells produce androgens, including testosterone, the primary male sex hormone. Their strategic positioning allows them to deliver hormones directly into the surrounding tissue and bloodstream for systemic effects.

Seminiferous tubules merge into a tubular network at the back of the testis called the rete testis. The rete testis connects to 15 to 20 efferent ductules, which lead directly to the accessory ducts of the male reproductive system. This pathway allows newly produced sperm to travel from the seminiferous tubules toward storage and maturation sites.

The pampiniform plexus is a network of interconnected veins surrounding the testicular arteries. It drains deoxygenated blood from the testis while simultaneously absorbing heat from the incoming oxygenated arterial blood. This heat exchange mechanism ensures optimal temperature maintenance, which is critical for healthy sperm production.

The testis requires precise temperature regulation to maintain normal sperm production. Deviation from the optimal temperature range disrupts the delicate process of spermatogenesis, leading to decreased fertility. The pampiniform plexus and testicular arteries work together to ensure the testicular tissue receives adequate nourishment and remains at the correct temperature.

Each testicular lobule contains one to three tightly coiled seminiferous tubules where sperm production occurs. Within these tubules, spermatogenic cells are arranged in layers along the walls, supported by Sertoli cells. Between adjacent seminiferous tubules lie interstitial cells that produce testosterone and other androgens essential for male reproduction.