Deciliation in the ampulla of the rat oviduct and effects of estrogen on the process

The mechanism by which cells in the ampullae of the rat oviducts undergo ra pid deciliation during each estrous cycle and the effects of estrogen on th e ciliated cells were examined. Untreated rats were killed on each day of t he 5-day estrous cycle, and the ampullae of their oviducts were removed. Ot her rats were injected subcutaneously each day for 5 days with 0.3 mu g or 3.0 mu g of estradiol benzoate or with 0.3 mg of tamoxifen, an estrogen ant agonist, per kilogram of body weight. The ampullae of the oviducts of the t reated rats were excised on the day following the last injection. The tissu es from all the rats were fixed in glutaraldehyde, stained with uranyl acet ate and lead citrate, and examined with a transmission electron microscope. Deciliation of cells was seen to occur by membrane-bound cilia packets (CP s) 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 d iestrus-2, suggesting that the process of deciliation is an ongoing one tha t merely changes in rate. No evidence of resorption of cilia was seen. Estr adiol treatment did not prevent CPs from forming, nor was tamoxifen treatme nt 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 ovi duct, that estrogen does not halt the process, and that ciliated cells may be transformed to secretory cells following loss of their cilia. J. Exp. Zo ol. 283:72-80, 1999. (C) 1999 Wiley-Liss, Inc.