The fine structure of the nervous tissue of the metacestode of Hymenolepis microstoma

Abstract

The cytology of the nervous tissues of the metacestode of H. microstoma was studied by EM. The small (3-5 .mu.m) nerve cell bodies are smooth to irregular in outline, possessing 1 to several neurities that form synapses in the neuropile. Each neuronal perikaryon contains a single nucleus with a single nucleolus, numnumerous free ribosomes, occasional polyribosomes, small numbers of .beta.-glycogen granules, multivesicular bodies, mitochondria, complex (coated or alveolate) vesicles, 1 or more Golgi complexes and variable numbers of vesicles. Microtubules and microfilaments, are absent from the perikaryon. Subsurface cisternae are well developed; their inner faces are studded with ribosomes. Five types of vesicles, believed to contain neurotransmitter and (or) neurosecretion were identified on the basis of vesicle osmophilia and size distribution. On the basis of vesicle content, 4 nerve cell types were identified: sensory neurons, 2 putative interneurons, and 1 neuronal type possessing characteristics of both interneurons and motor neurons.