Studies on the ultrastructure of the integument of the rotifer Habrotrocha rosa Donner (Aschelminthes).

The integument of the rotifer Habrotrocha rosa Donner is provided with pores and formed by an extrasyncytial cuticle and a syncytial hypodermis. This hypodermis peripherally contains 3 layers of dense cytoplasm and borders the cuticle by an asymmetric cell membrane. The wall of the pores is stiffened proximally like an annulus. The pores lead into cytoplasmic invaginations which are surrounded by vesicles. Close to and also beneath the condensed cytoplasmic layers microbodies are found, which are interpreted as microperoxisomes. Subhypodermal layers of muscles are connected with the cytoplasm of the hypodermis by desmosome-like structures.