SYNTHESIS AND SECRETION OF LIPIDS BY BOVINE OVIDUCT MUCOSAL EXPLANTS

The objectives of this study were to determine the types of lipid synt hesized and secreted by the bovine oviduct, and to determine whether l ipid synthesis and secretion varied with stage of the ovarian cycle an d oviductal region. Oviduct explant cultures were prepared from cows k illed during either the follicular or luteal stage of the oestrous cyc le. Both stage of ovarian cycle and oviductal region affected lipid sy nthesis by oviductal explants in vitro. More lipid was synthesized by explants from follicular than from luteal-stage cows. Ampullar explant s synthesized the greatest quantity of total lipid, followed by the pr eampulla and isthmus. Separation of extracted lipids from cultured tis sue by high performance thin-layer chromatography (HPTLC) resolved pho sphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosph atidylinositol, cardiolipin, free cholesterol, free fatty acid, trigly ceride and esterified cholesterol, all of which were synthesized durin g culture. The ampulla synthesized significantly more phosphatidyletha nolamine, phosphatidylserine and phosphatidylinositol than did the oth er regions. Culture supernatants from ampullary explants contained the most newly synthesized cholesterol when compared with other regions. The histochemical location of neutral lipid droplets in the epithelium of cultured explants paralleled the localization of radioactivity in autoradiographs of explant extracts. The results suggest that the ovid uct synthesizes a variety of lipids, and that some of these are releas ed into culture supernatants.