Effect of fat body excision on vitellogenic growth of oocytes in Rana tigerina

Abstract

In R. tigerina ovaries and fat bodies undergo annual cyclical changes. The fat bodies, well developed between September-March, begin to reduce in size from April onwards reaching a nadir in July-August. The decline in fat body size is correlated with the vitellogenic growth of oocytes and subsequent breeding. Bilateral fat body excision (fatectomy) in the first week of April retarded the vitellogenic growth of oocytes and therefore the mean size of the largest oocytes was significantly lower than in the sham operated controls (p<0.001) after 30 days as the incorporation of yolk was less. In the controls the vitellogenesis was complete. The gonadosomatic index and the mean weights of ovaries and oviducts did not change following fatectomy. These findings suggest that the fat bodies in the frog have a supporting role in the vitellogenic processes.