Between 1928 and 1937, Berta and Ernst Scharrer (1906-1995) explored the idea of neurosecretion for the first time. The neurosecretory cell, which resembles a "tear drop," is both glandular and neuronal in form. It is consistent with the ultrastructure of the cells that the neurosecretory products (neurosecretion/neurohormone) are proteinaceous in nature. Normally, neurosecretory substances are discharged into the blood capillaries by way of an axon.
Regardless of their ecological classifications, the location, structure, and activities of neurosecretory cells in the central nervous systems of various earthworm species are more or less the same. The central nervous system of tropical earthworms exhibits two primary types of neurosecretory cells: deeply stained A type cells (deeply stained AF positive cells with characteristic axonal processes in the outer cortical tier) and lightly stained B type cells (lying in between A type cells and central fibrous neuropile). Neural lamella and epineurium surround the neurosecretory cells of the central nervous system on all sides. The central nervous system's "medulla" is made up of vascularized and fibrous neuropile. At the base of the circumesophageal connectives of the subesophageal ganglia, there are S cells or Hubl cells in addition to A and B cells, which make up a "islet" of neurosecretory cells. At the "zone of accumulation," a highly vascularized fibrous neuropile that can be considered a "elementary neuro-haemal organ," both A and B cells release (neurohormone). In Oligochaetes, neurosecretion affects a variety of processes including feeding, osmoregulation, thermal acclimatisation, regeneration, copulation, cocoon formation, and oogenesis.
Author (s) Details
Priyasankar Chaudhuri
Earthworm Research Laboratory, Department
of Zoology, Tripura University (A central University), Suryamaninagar-799022,
Tripura West, India.
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