ISSN:
0362-2525
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
Histological studies of the neurosecretory system during the postembryonic development of a spider, Argiope aurantia, were made at the light-microscopic level.Neurosecretory cells which are found in all stages are classified into type I and type II cells. The type I cells are present in the aboral region of the brain and in pedipalpal, ambulatory and abdominal ganglia of the subesophageal mass. The type II cells which appear from the seventh stage are confined to the cheliceral ganglia. Three stages of secretory activity (poor, medium and full) based on stainability are described in these cells.In both types clear axonal transportation of neurosecretory material is observed. The discrete tracts and commissures formed by these neurosecretory axons are described in the brain and subesophageal ganglion. The complexity of some of these pathways is comparable to that of the ordinary neurons.One pair of nerves from the brain and four pairs of nerves from the subesophageal mass enter a neurohaemal organ, the Tropfenkomplex. This is a paired structure, situated dorsally, on either side of the subesophageal mass. The neurosecretory axons branch extensively within the organ and on their course they from sacs or pools filled with secretory material.The Tropfenkomplex is enveloped by a thin neural sheath which runs deep into the organ dividing it into a series of lobes. Glial cells are distributed within the organ. As in the neurosecretory cells, changes in stainability of secretory material were also observed in the Tropfenkomplex.During intermolt periods two peaks of stainability have been noticed. The first peak lasts for 24 hours after the molt, and this is followed by a low activity period between second and fifth day. From the sixth to the tenth day after the molt the second peak commences. It is suggested that the second peak may be responsible for bringing about molting.The cheliceral group appears (seventh stage) at a time when external indication of reproductive characters are visible. In the ninth stage, by the tenth day after the last molt, several of the type I and type II cells contain much secretion. This is followed by maturation of gonads and oviposition. Thus both type I and type II cells are believed to be involved in the reproduction of the animal.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jmor.1051410105
