Ultrastructural peculiarities of the chemical transmission of the nerve impulse in the gravity receptors of some invertebrates.

Electron microscopic and cytochemical studies of the synapses of the gravity receptors in Coelenterata, Ctenophora, Annelids and Molluscs has shown the mediators both of cholinergic and adrenergic systems. As a rule, the two mediatros were connected with different receptor systems (Ctenophora) or with the synaptic structures of various parts of the chain: receptor--neuron--effector (Medusa, Annelids). The synaptic transmission in the gravity receptor of studied molluscs classes is carried out by means of either cholinergic or adrenergic systems.