Testes - Structure of Testis

Seminiferous tubules (semini: sperm, ferous: bearing) where the sperms are produced. The process is called spermatogenesis.

Each testis is enclosed by three concentric protective layers called tunics:

1. Testicular Lobules

• Each testis is divided into approximately 250 testicular lobules by septa.
• Each lobule contains 1 to 4 highly coiled seminiferous tubules.
• Total seminiferous tubules across both testes: approximately 750–1000.

2. Seminiferous Tubules: The Site of Spermatogenesis

• Highly coiled tubular structures lined by stratified germinal epithelium.
• Contain two distinct cell populations inside the tubule and one outside:

Cell Types Inside the Seminiferous Tubules

Cell Types Outside the Seminiferous Tubules

Internal morphology of testis

Testis in transverse section

• Each testis is enclosed by three protective layers – tunica vaginalis, tunica albuginea, and tunica vasculosa.
• Internally, each testis is divided into about 250 testicular lobules.
• Each lobule contains highly coiled seminiferous tubules, which are the site of spermatogenesis.
• The wall of seminiferous tubules is lined by germinal epithelium consisting of spermatogonia, Sertoli cells, and interstitial cells.
• Spermatogonia are diploid male germ cells that undergo meiosis to form haploid sperms.
• Sertoli cells act as nurse cells, providing nourishment and support to developing sperms, while Leydig cells secrete testosterone.
• Sperms move from seminiferous tubules into efferent ducts, then to the epididymis for maturation and temporary storage before entering the vas deferens.