On the basis of various histological changes the ovarian cycle of Mastacembelus armatus can be divided in to five different phases i.e. resting, maturation, prespawning, spawning and postspawning phases. Seasonal cyclic changes in the plasma calcium and calcitonin level were found associated with this ovarian cycle. An increase in their level occurs during maturation phase with a correspond ing increase in the gonadosomatic index reaching the peak during prespawning phase and spawning phase. On the other hand a significant decrease was noted during postspawning and resting phase. Histological changes in the ultimobranchial gland also revealed the seasonal variation in its activity. It exhibits various signs of hyperactivity like Maximum increase in the population of secretory cells, decrease in size of lumen and dilation of blood vessels during prespawning and spawning phase. Disruptive follicular organization was noted during resting and po st spawning phase. 17-â estradiol administration resulted in hypercalcemia and increase in plasma calcitonin level in M. armatus fed with calcium deficient food. Therefore it can be concluded that UBG is mainly concerned with reproductive physiology of the fish M. Armatus by lowering down elevated plasma calcium level accompanied through extra intestinal routes during ovarian maturation.

The present paper devoted to dual integral equations involving non stationary Heat conduction equation in the Laplace Transform for two d i m e n s i o n a l s y m m e t r i c a l u n d e r m i x e d d i s c o n t i n u o u s b o u n d a r y conditions acted on level surface of semi space in spherical co-ordinates we find temperature distribution function of moving solid object along a surface of semi space with velocity v by consideration of non-stationary heat conduction equation and Heat source m (r, t) inside a disc of radius c, 1 r < c, outside of disc r > c, a temperature function m (r, t) is given. We use 2 operational calculus method and dual integral equation for the solution of given boundary value problem