Influence of thyroxine on ovarian glycogen of Bombyx mori L. (Race Nistari) during ontogenesis

Abstract

Normal variations of ovarian glycogen content and the effect of different doses of thyroxine (T4) on this cellular constituent were investigated from 3rd day of fifth larval instar to adult emergence in Bombyx mori L. Ovarian glycogen remained higher during fifth larval stage with a peak on 7th day. At the end of 5th larval stage the glycogen content declined and this lower level continued upto 4th day of pupal age. Thereafter, this cellular constituent again sharply increased and reached a peak on pupal day 6, followed by a fall upto adult emergence. A single injection of different doses (0.5,1, 2 and 5 μg/g body weight) of thyroxine, caused a significant decrease in glycogen content of ovary, during larval stage and an increase during pupal and adult stages of development with few exceptions. Thyroxine at the doses of 0.1 and 0.25 μg/g remained ineffective throughout the study period with an exception on day 2 after injection. The specific pattern of variation of the ovarian glycogen content as observed during normal stages of development was not altered by thyroxin though this hormone changed the level of glycogen. Thus, the results indicated that both glycogenosis and glycogenesis occur in ovary after thyroxine treatment.