The effect of starvation on the ultrastructure of the digestive cells of Dolops ranarum (Stuhlmann, 1891) (Crustacea: Branchiura)

Transmission electron microscopy was conducted on the digestive epithelium of the crustacean ectoparasite Dolops ranarum to elucidate its ultrastructure for the first time, both in a nourished and starved condition. Specimens were collected from the Limpopo Drainage System in South Africa, and the specimens were killed and dissected in Todd's fixative. The anterior midgut is composed mostly of absorptive cells or R cells, while the diverticula are composed of R cells and of F cells, which are moderately abundant in rough endoplasmic reticulum. They are probably responsible for producing digestive enzymes. The posterior midgut is composed of papilliform B cells with large apically located vesicles and R′ cells devoid of cell inclusions. Under starvation, specimens survive for a maximum of 12 days; R cells show the most conspicuous changes in ultrastructural characteristics. It is concluded that D. ranarum has adapted to short-term survival only without a host.