The anatomy and histology of the ecdysial glands of Philosamia ricini (Hutt.) (Lepidoptera: Saturniidae) during the post embryonic development.

A comprehensive account of the anatomy and histophysiology of the ecdysial glands of Philosamia ricini during post embryonic development has been given. The study clearly indicates an increase in number of cells in each larval instar by endomitosis. The maximum number of cells are present in the 5th instar larvae. The cell size decreases before moulting in each instar. The size and shape of the cells of the glands vary considerably from individual to individual or even in the same individual. They are oval, elongate, polygonal in outline. Gland is collectively innervated by transverse nerves arising from the suboesophageal, prothoracic, mesothoracic and metathoracic ganglia as well as medial-1 and medial-2 nerves. The secretory activity of the glands is indicated by a large amount of cytoplasm with a developed brush border, having vacuoles at the periphery. The inactive glands have small amount of cytoplasm, without vacuoles and poorly developed brush border. The glands are absent in the newly moulted adults indicating that they degenerate before imaginal ecdysis.