Granular, ciliated cells in the anterior pituitaries of immature rats.

In this communication we demonstrate a new type of ciliated cell in the pituitary gland of immature rats. Anterior pituitary glands of rats, 31 days of age, were examined by electron microscopy. Around the agranular cells, which lined small cavities, there were sparsely granulated cells with many cilia (granular, ciliated cells). Their small granules, which were distributed along the cell membrane, had limiting membranes. Their cilia were of 9+2 type with a central pair of microtubules. It was suggested that the granular, ciliated cells might be an intermediate-type of cell for the different types of pituitary cells, which appear temporarily during pituitary ontogenesis.