In the anterior pituitaries of adult rats of both sexes, follicular cells resemble marginal layer cells in fine structure. Numerous occurrences of cilia were electronmicroscopically confirmed on the free surface of both cells. The absence of secretory granules, the poor development of endoplasmic reticula and abundant free ribosomes and polysomes are the other coincidental cytological properties between both cells showing the immaturity. Thus, the two cells seem to be intimately related. The follicular cells may play an important role in the mitotic activity of the gland. Cilia and microvilli on the free surface of follicular cells are not easily changed by some experimental conditions.
The Japan Endocrine Society