Fine structure of Leydig cells in crabeater, leopard and Ross seals.

Ultrastructural study of the Leydig cells of nonbreeding crabeater, leopard and Ross seals showed that three types of cells could be distinguished. Type I cells possessed the cytological features typical of steroid-secreting cells. Type II cells exhibited various features of degeneration, e.g. accumulation of large amounts of lipofuscin granules (residual bodies), lipid droplets, secondary lysosomes, rectangular crystalloids, and previously undescribed 'peculiar bodies'. These cellular inclusions and debris were released into the interstitium to be phagocytosed by macrophages and/or resorbed by the lymphatics. Type III Leydig cells contained large amounts of lipid droplets, sparse cytoplasmic organelles and essentially became lipid storage cells.