Histological and ultrastructural study of the muscular and nervous systems inHydra. II. Nervous system

摘要: Nerve cells in hydra have been studied with the light and electron microscopes. Techniques for observing bi-polar, tri-polar, multi-polar sensory are described. Evidence is presented that these form a major part of nervous system hydra. The ultrastructural studies indicate following: (1) There three types nerve cells: ganglionic, neurosecretory. (2) concentrated at base tentacles, hypostome basal regions. (3) situated adjacent to muscle fibers epithelio-muscular cells. Criteria identification level presented. The appear be structurally different from similar higher invertebrates vertebrates. An important distinction lack specialized synaptic vesicles appearance, dimensions, location secretory droplets identified as neurosecretory discussed. resemble closely mechanism release material appears suggested organisms. It one type droplet may represent growth stimulating principle believed control differentiation (Burnett, '66). relationship processes