Alkaline phosphomonesterase activity in spinning gland cells of the moth pericallia ricini during sequential stages of growth and atrophy.

Alkaline phosphatase becomes active in the cytoplasm of the spinning gland cells of the third instar larva, where it is confined only to the apical (luminal) border of cells. In the fourth instar hydrolase activity spreads to the middle region of the cells. In Pre-pupa, when production of silk is at its maximum, activity of alkaline phosphatase in the cells of the spinning gland is much reduced than in the preceding fourth instar stage. In degenerating phase activity of the enzyme is restricted only to the peripheral region of the cells. Its role in the physiology of the cells of the spinning gland of Pericallia ricini is discussed. Unlike acid hydrolase, alkaline phosphatase activity and distribution is similar in all the cells of spinning gland during development and degeneration.