Ultrastructural identification of folliculo-stellate cells in the pars distalis of the cat and dog pituitary gland.

Ultrastructural features of folliculo-stellate cells of the anterior lobe of the pituitary gland have been described in the cat and dog. These cells are agranular and form the lining of tiny follicles into which microvilli project. Long expanding cytoplasmic processes are intermingled with granular cells of various types without special relationships to one cell type or another. A few features are reported which are peculiar to each species. The results are compared with those previously described.