Histology of the oviduct of the leopard frog, Rana pipiens

The first one to three mm of each of the paired female oviducts in Rana pipiens consists of a folded mucosa lacking tubular glands and enclosed by a serosa. Most of the remainder of the oviduct is lined by a folded mucosa richly endowed with simple tubular, jelly‐secreting glands. The final one to two cm of the uterine portion of the oviduct, however, has a smooth mucosal lining which lacks tubular glands. Jelly‐secreting glands penetrate to the base of the mucosa and open to the lumen between ridges capped with ciliated or mucous secreting epithelial cells. As cells of the jelly‐secreting glands grow and differentiate during the summer, they accumulate a granular secretory product which exhibits basohpilia in hematoxylinstained specimens. This is the essential change in the histological structure of the gland throughout the growing season. The adult male oviduct is a solid cord of cells for about one‐third of its length. The inferior two‐thirds, however, is like the female oviduct at an intermediate stage of seasonal growth with gland cells containing secretory granules which exhibit basophilia.