Light micrograph of a transverse section through a mammalian testis showing the seminiferous tubules, highly convoluted tubes lined with a stratified epithelium. The production of male gametes (spermatogenesis) and the subsequent development of these gametes into motile spermatozoa (spermiogenesis) both take place within this epithelium. Sertoli cells, which provide support and nourishment for the developing spermatozoa, are also found within the epithelium. Leydig cells, which have an endocrine function, are found either singly or in clumps in the interstitial spaces between the tubules. Magnification: x200 at 35mm size. RAT TESTIS