Proepithelial Regeneration in the Midgut of Beetles

Abstract

THE columnar cells of the midgut epithelium in most insects are continually replaced by new cells produced by the division of special regenerative cells. The latter are usually scattered singly or grouped into nidi or else form deep crypts. Pradhan¹, however, described a new process in Coccinella septempunctata (Coleoptera, Coccinellidae) and other carnivorous coccinellids where the new cells (pro-epithelial cells) are grouped around large cavities or vacuoles. When the old epithelium is shed, the pro-epithelial cells move into their place. He states that “the presence of this peculiar process of regeneration (pro-epithelial regeneration) in the carnivorous coccinellids and its absence in the herbivorous species forms the most striking difference between the carnivorous and herbivorous midguts”. However, in the case of Epilachna vigintioctopunctata Fabr., a common herbivorous coccinellid studied by us, pro-epithelial cells grouped around large vacuoles (about 20µ in diameter) could easily be seen (Fig. 1). The vacuoles are present throughout the midgut but are most clearly seen in the middle portion of it.