A reliable method for isolating endometrial epithelial cells from rabbits, and preliminary studies of prostaglandin uptake.

Endometrial epithelial cells were isolated enzymatically from intact, everted uteri of mature rabbits and then by sedimentation at unit gravity. Electron-microscopic examination of these cells taken from estrous and pseudopregnant animals showed that the preparation contained almost pure endometrial cells in the form of "plaques" with little contamination with other cell types. The cells were judged viable on the basis of the trypan blue exclusion test and the presence of motile cilia. It was observed that pinocytotic activity was greatest at estrus, and declined thereafter, while release of secretory granules increased during pseudopregnancy. There was also a marked increase in the number of free ribosomes and mitochondria as pseudopregnancy progressed (estrus less than 4 day less than 6 day less than 7 day). The cisternae of the rough endoplasmic reticulum were least at 6 days and the Golgi stacks greatest in size and number at 7 days. The uptake of prostaglandin (PG) E2 and F2 alpha by epithelial cells isolated from rabbits at estrus and at 4, 6, and 7 days of pseudopregnancy was then determined. The magnitude of PG accumulation was found to vary among the different groups. At low extracellular concentrations, accumulation of both PGE2 and PGF2 alpha was greatest in the estrous state, much less at 4 days, and least at 6 days of pseudopregnancy. At 7 days of pseudopregnancy, the uptake of PGs was similar to those values obtained at 4 days. These studies indicate that both PGE2 and PGF2 alpha are accumulated by epithelial endometrial cells as a result of a mechanism(s) that is more complex than a saturable, specific receptor-dependent binding system.