THE LIPIDS OF THE CROP EPITHELIUM OF PIGEONS AFTER INJECTION WITH PROLACTIN FROM THE PITUITARIES OF DIFFERENT VERTEBRATE CLASSES

Abstract

SUMMARY The histological appearance, the lipid content and composition of the epithelium of the pigeon crop were investigated after intradermal injection of extracts containing prolactin from representatives of several vertebrate classes. Lipids from crop 'milk' and body depot fat were also studied. There was significantly more lipid in stimulated crop tissue than in the unstimulated crop but significantly less than in crop 'milk', which had approximately half the concentration present in depot fat. Although the lipid staining of histological sections of crops of pigeons injected with prolactin from different vertebrate classes differed strikingly, no difference in lipid concentration in the crop tissue was detected. Equally there were no striking differences between the fatty acid compositions of the triglycerides extracted from the different crops or between these and the triglycerides of crop 'milk' or depot fat. The implications of these findings regarding the effects of prolactin in the pigeon and possible attributes of prolactin from different vertebrate classes are discussed.