The mammalian oviduct especially the ampulla part plays an essential role in female reproduction as fertilization, oocyte maturation and early embryonic development. The present study was focused on the microscopic changes of the rat ampulla epithelium during the oestrous cycle and correlates the findings with their possible functions. Twenty five rats of regular 5 day oestrous cycles were used in our study. They were divided into 5 groups; five rats in each phase of estrous cycle (early proestrus, late proestrus, estrus, metestrus and diestrus). They were sacrificed and the ampullae were excised, fixed and processed to be examined by light and electron microscopy. Marked changes in both relative number and the structure of ciliated and secretory cells throughout the estrous cycle were seen. Ciliated cells were increased in the relative number at the early proestrus till became the predominant cell type at the late proestrus then decreased at the estrus phase accompanied by deciliation. The secretory cells increased in the relative number and prevailed at the metestrus with increasing in the secretory activity. They became rare at the diestrus, a day on which the first sign of neociliogenesis was recorded. Intra epithelial glands were firstly appeared at the estrus phase which increased in number and size at the metestrus. The secretory material is showed PAS positive reaction in the estrus and the metestrus.

The mechanism by which cells in the ampullae of the rat oviducts undergo rapid deciliation during each estrous cycle and the effects of estrogen on the ciliated cells were examined. Untreated rats were killed on each day of the 5-day estrous cycle, and the ampullae of their oviducts were removed. Other rats were injected subcutaneously each day for 5 days with 0.3 microgram or 3.0 micrograms of estradiol benzoate or with 0.3 mg of tamoxifen, an estrogen antagonist, per kilogram of body weight. The ampullae of the oviducts of the treated rats were excised on the day following the last injection. The tissues from all the rats were fixed in glutaraldehyde, stained with uranyl acetate and lead citrate, and examined with a transmission electron microscope. Deciliation of cells was seen to occur by membrane-bound cilia packets (CPs) forming at the apices of cells and pinching off. Although CPs were more numerous at proestrus, they were also observed at estrus, diestrus-1, and diestrus-2, suggesting that the process of deciliation is an ongoing one that merely changes in rate. No evidence of resorption of cilia was seen. Estradiol treatment did not prevent CPs from forming, nor was tamoxifen treatment associated with any apparent enhancement of deciliation. Ciliated cells with CPs stained more darkly than ciliated cells that were without CPs, and the former appeared similar in their staining characteristics to secretory cells, most of which stain darkly. It was concluded that the cells of the ampulla deciliate rapidly by shedding their cilia into the lumen of the oviduct, that estrogen does not halt the process, and that ciliated cells may be transformed to secretory cells following loss of their cilia.

The histochemistry and ultrastructure (SEM and TEM) of the spermatheca of Biomphalaria glabrata was investigated to elucidate the function of this organ and to compare its structure and function to similar organs found in other species. The spermatheca has a debris-filled lumen surrounded by a thin wall of tissue. The cells adjacent to the lumen are of three columnar epithelial cell types. Two cell types have abundant microvilli and mammalian cell-like organelle distribution and morphology. The above cell types differ in the electron density of their cytoplasms, nuclear morphologies, and organelle content. The third cell type differs from the other two in its cytoplasmic makeup. However, the most distinctive difference is the presence of large numbers of cilia at the apical surface with no evidence of microvilli. These columnar cells rest on a basal lamina adjacent to a two to three cell thick muscle layer. The entire organ is surrounded by an adventitia of unusual morphology. Histochemical investigation demonstrated that DNAase, RNAase, and protease are present in the lumen, alkaline phosphatase is associated primarily with the microvilli, small amounts of acid phosphatase are concentrated in the midcell area of the columnar epithelium, and ATPase activity is localized in the muscle cells and just below the absorptive surface of the microvillous cells. The luminal contents and adventitial areas are Sudan Black B positive, all areas of the lumen and organ wall are PAS positive, the cell nuclei and amorphous masses in the lumen showed Feulgen staining, and large vesicles in the columnar cells were Oil Red O positive. Apparently, the spermatheca of B. glabrata is both a digestive and absorptive structure. Although this organ shares functional similarities with those found in opisthobranchs and terrestrial pulmonates, the epithelia of the spermatheca differ dramatically in these groups.

The ultrastructure of the spermatheca of the reproductive tract in the pulmonate snail, Sonorella santaritana, was investigated. This organ has a debris-filled lumen and an outer wall which can be divided into three distinct layers. The cell layer adjacent to the lumen is comprised of two cell types, tall columnar epithelial cells with microvilli and cells lacking microvilli. The next layer also has two cell types, muscle cells and apparent pigment cells. The most distant layer is an adventitia of large glycogen-containing cells. The lumen of the spermatheca contains a core of partially digested sperm and related materials. The luminal contents and the cellular morphology of this organ suggest that the spermathecal functions are both digestive and absorptive. It is proposed that excess sperm and related materials are transported to the spermatheca, digested, and the usable products are reabsorbed.

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