NEUROSECRETION IN THE THORACIC GANGLION OF THE CRAB, ERIOCHEIR JAPONICUS

Abstract

1. The different types of nerve cells occurring in the thoracic ganglion of the fresh water crab. Eriocheir japonicus, their distribution, neurosecretory activity, and the mode of discharge of the neurosecretory substances were studied. 2. There are four types of nerve cells which show a definite localization in the thoracic ganglion; three of them are considered to be neurosecretory cells. Giant A-cells are interpreted as neurosecretory cells on account of the cyclic changes of their nuclei and the gradual movement of many small vacuoles toward the cell periphery. B-cells are small cells showing secretory cycles: numerous granules appear in the cytoplasm, then concentrate into one or two masses at the edge of the cells, and finally disappear leaving large vacuoles in their place. Their nuclei show no changes. C-cells are also small neurosecretory cells; they are thought to correspond to Enami's β cells. The minute D-cells do not posses characteristics to suggest a secretory activity. 3. Several small arteries enter into the thoracic ganglion at the mid-ventral region and pass through to the dorsal side, branching out into many capillaries. These capillaries form networks and closely surround the neurosecretory cells. 4. From these observationsitis concluded that the neurosecretory substances in these cells are given off into the capillaries and thus reach the general circulation of the body. This mode of discharge of the cellular product is of interest in view of comparable mechanisms in vertebrates. 5. The physiological activities of these neurosecretory substances in the thoracic ganglion of Eriocheir are as yet unknown.