Secretion granules in the ciliated cells of the avian oviduct.

The avian oviduct is subdivided into five regions according to its function in egg formation and histological features. They are the infundibulum, albumen secreting region (magnum), isthmus, shell gland (uterus), and vagina. The epithelium of these regions consists of ciliated and nonciliated cells. In addition to secretion granules, specific to each region, in the non-ciliated cells, considerable numbers of granules in the ciliated cell are characteristic to this organ. In the infundibulum a small number of moderately dense granules are seen both in laying and non-laying birds. The ciliated cells in the magnum have mucous type globules which appear to increase in number in non-laying birds suggesting that they may represent reabsorbed mucous. The isthmus ciliated cell contains complextype granules composed of a dense cortex and a less dense core. This type of granules are increased in laying birds. Large dense granules are located in the uterus and in the adjacent areas. This type also increases in laying birds. Discharged gramule content was found in the lumen keeping its continuity with the apical granules. These findings were evident in the hen, duck, quail and pigeon. ACPase was not detected and ATPase activity was weak in the dense granule. TPPase appeared to be localized in some of the granules. Electron probe microanalysis of the dense granules did not prove a significant concentration of Ca, indicating that the uterine ciliated cell may not be involved in shell formarion in the uterus gland.