The identity of the so-called crescent cell in the hemolymph of the cockroach, Gromphadorhina portentosa (Schaum) (Dictyoptera: Blaberidae)

Abstract

The identity of the so-called cresecent cell in the hemolymph of the cockroach, Gromphadorhina portentosa (Schaum) (Dictyoptera: Blaberidae) has been established. These hemocytes are indeed oenocytoids (OEs). The identity of these cells was con-firmed by observations in both the last instar nymphs and adults. The OEs appear as polymorphic anucleate cells. Each OE has a crescent-shaped inclusion body that generally fills the cell and gradually diminishes in size and density as the cell ages. The OEs vary from 16 to 28μm in length and 10 to 22.4μm in width. They generally constitute 2% of the total hemocyte counts in both nymphs and adults. The most peculiar features of the OEs in this cockroach are presence of a single crescent-shaped cytoplasmic body and gradual nuclear extrusion as these cells age. No nuclear extrusion was observed in any of the other five types of hemocytes found in this cockroach. The nuclear extrusion may occur at any point along the length of the cell, thus producing the various forms of anucleate cells. Histochemically, the inclusion body shows intense PAS-positivity and is Sudan Black B-negative. These cells may nlav an indirect role in the final stages of cuticle formation.