Lipid Distribution Variations in Different Stages of Cyclic Corpus Luteum of Indian Buffalo

The present study was conducted on corpus luteum of healthy buffaloes ovaries (n = 24) collected from local slaughter house and were categorized into early (stage I, 1 to 5 days, n=6), mid (stage II, 6 to 11 days, n = 6), late luteal phase (stage III, 12 to 16 days, n = 6) and regressing phase (stage IV, 17 to 20 days, n=6). In the earliest phase i.e., corpus haemorrhagicum, the distribution of total lipids was moderate. However, in the early luteal phase, most of the luteal cells had intense staining for presence of total lipids by Sudan Black B and Oil Red O and phospholipids by Acid Hematin. By the mid luteal phase, fewer luteal cells at this stage showed positive staining for presence of lipids. During the mid luteal phase, the less frequent presence of lipid droplets in luteal cells indicated that cholesterol and its esters present at this stage might have been utilized for active synthesis of progesterone. In late luteal phase, the distribution of lipids increased to depict very intense staining. Moreover, in the regressing phase i.e., corpus albicans, the distribution of lipids increased further and was observed to be both intracellular and extracellular depicting the higher accumulation of lipids in the regressing corpus luteum. The increase in the lipid droplets in luteal cells at this stage indicated the poor mobilization of lipids and thus decline in the progesterone synthesis.