Pig endometrial cells in primary culture: morphology, secretion of prostaglandins and proteins, and effects of pregnancy

Luminal epithelial, glandular epithelial, and stromal cells were isolated from pig endometrium by enzymatic dispersion and sieve filtration. The three cell types, maintained in primary culture, showed distinctly different morphologies when viewed by light and scanning electron microscopy. Immunocytochemical staining indicated that luminal and glandular epithelial cells were positive for both cytokeratin and vimentin. However, stromal cells were positive only for vimentin. Acid phosphatase activity was detected in the culture medium of glandular cells and increased (P < .05) when progesterone (.1 µM) was included in the culture medium. The secretion of uteroferrin by glandular cells was also indicated by one-dimensional PAGE and Western blot analysis. Stromal cells produced more (P < .01) prostaglandin E (PGE) than prostaglandin F2α (PGF2α), whereas glandular cells secreted more (P < .01) PGF2α than PGE. Pregnancy status affected prostaglandin secretion in that stromal cells secreted less (P < .01) PGE and PGF2Α and glandular cells secreted less (P < .05) PGF2α when they were harvested from pregnant vs cyclic pigs. Furthermore, the PGE:PGF2α ratio in medium from stromal cells was greater (P < .01) for cells collected from pregnant pigs. This culture system provides an in vitro model for studying the hormonal regulation of the endometrium and potentially may be useful for studying interactions between endometrial cells and embryos in the pig.