[Electronmicroscopic study of the gravity receptors in ctenophores].

Secondarily sensitive receptor balancer cells comprise the gravity receptor in the aboral organ-polivalent organ of Ctenophora. Ctenophora are phylogenetically the first animals which created receptor cell supplied with a single flagellar kinocilium connected with the otolithic apparatus. The receptor balancer cells are innervated by the nerve fiber branched off the nerve cells of the aboral ganglion. The localization of AChE, BuChE products of cytochemical reaction on sodium suggests that the cholinergic mechanism may take part in the process of synaptic transmission. Our morphological data cannot exclude an adrenergic mechanizm also.