Procambarus simulans: Light-Induced Changes in Neurosecretory Cells and in Ovarian Cycle

PERRYMAN, E. K. 1969. Procambarus simulans: Light-induced changes in neurosecretory cells and in ovarian cycle. Trans. Amer. Micros. Soc. 88: 514-524. Mature and immature female crayfish, Procambarus simulans, were exposed to varying photoperiods (number of hours of light in a 24-hour period). Increase of photoperiod induced a more rapid cycling of maturation and resorption of oocytes in both mature and immature animals. Decrease of photoperiod tended to stabilize the ovary in a mature condition. Histological examination of ovarian sections and determination of ovarian weight revealed three definite stages in the ovarian maturation process: cyclic oocyte formation, maturation, and destruction. At different periods of the ovarian cycle, varying amounts of neurosecretory material were located in the neurosecretory cells of the supraesophageal ganglia and eyestalk. Microtomical sections showed four basic types of neurosecretory cells. Correlation of the cell types with the ovarian cycle indicated cell type one of the medulla terminalis x-organ of the eyestalk produced an inhibitor that restricted the proliferation of new oocytes until the mature ones had been ovulated or resorbed. Cell type three apparently produced a secretory material that hastened ovulation or resorption of yolk. The localization of the production sites of these two substances, the inhibitor of new oocytes and the accelerator of ovulation, supports the ideas of endocrine control proposed by previous researchers.