Histological and Histochemical Changes in Bovine Endometrium Following Treatment with a Progestin

Abstract

Melengesterol acetate (MGA), a synthetic progestin, was fed to 15 beef heifers at 1.0 rag per animal per day for 14 days. Eight animals were started on the MGA feeding at day 4 (4-day animals) and 7 animals were started at day 15 (15-day animals) of the estrous cycle. Five control animals were not treated with MGA. The heifers were mated at the synchronized estrus and slaughtered 3 days later. Fertilization and the number of ova undergoing normal cleavage were reduced in heifers treated with MGA as compared to control heifers. The surface and glandular epithelial cells of the endometrium from control animals contained moderate to heavy concentrations of glycogen; however, there was little evidence of glycogen accumulation in the surface epithelial cells of 15-day animals. Although different, glycogen accumulation in the endometrial surface epithelial cells from 4-day animals was more like the controls than like the 15-day animals. These results suggest a diminished estrogen secretion or a failure of the endometrium of MGA treated heifers to respond to estrogen. © 1971, American Dairy Science Association. All rights reserved.