Sertoli cell development of pig testis in the fetal and neonatal period.

The Sertoli cells of pig fetuses from 35 days postcoitum until 1 mo after birth have been investigated by light and electron microscopy in decapitated animals and their control littermates, as well as in untreated animals. Until 52 days postcoitum, Sertoli cells change in form during the formation of sex cords but from then onwards they are rather uniform. They primarily display an elongated nonindented nucleus with one or more prominent nucleoli, a well-developed Golgi apparatus, and in the basal compartment below or beside the nucleus, a large lipid droplet. There are large quantities of rough endoplasmic reticulum (RER) from 52 days postcoitum onwards, often with complex whirl forms and a parallel arrangement of profiles with relatively few ribosomes. After birth their numbers seem to be somewhat less, and by 1 mo after birth the RER profiles are often shorter and almost free of ribosomes. Clustered ribosomes are found in large quantities throughout the period under investigation. Especially in the early fetal period, the endoplasmic reticulum (ER) profiles show prominently filled cisternae. Mitochondria are mostly long and slender, or small and ovoid. Most have lamellar cristae, but mixed lamellar-tubular cristae can also be seen. Between decapitated, control and untreated animals no obvious ultrastructural differences could be observed. The peritubular cell sheath surrounding the sex cords did not show signs of differentiation into a layer of myoid cells.