Describe structure of a seminiferous tubule.

Each testicular lobule has tightly coiled seminiferous tubules which are packed with cells undergoing spermatogenesis (spermatogonia) and Sertoli cells. A germinal epithelium of delicate connective tissue surrounds the seminiferous tubules. The large sustentacular cells that extend from the capsule to the lumen of the seminiferous tubule are called Sertoli cells. They serve to support, nourish and regulate the development of cells undergoing spermatogenesis. The endocrine cells present in the space between seminiferous tubules are termed as interstitial cells of Leydig. They serve to secrete androgen, testosterone.