Endocrine control by neurosecretory cells of the pars intercerebralis and the corpora allata during the earlier phases of vitellogenesis in Locusta migratoria migratorioides R and F ( Orthoptera)

Abstract

In the adult female Locusta migratoria, the neurosecretory cells (A,B,C) of the pars intercerebralis and the corpora allata are essential for the onset of the second phase of vitellogenesis, which is characterized by the uptake of yolk proteins by the oocyte. Electrocoagulation of the neurosecretory cells inhibits vitellogenesis only if this operation is performed during the first five days of adult life (oocyte length from 0.4 to 1 mm). On the other hand, the presence of the corpora allata is essential for vitellogenesis until the beginning of the second phase of vitellogenesis (oocyte length from 0.4 to 4 mm). Implantation of one pair of corpora allata or an injection of juvenile hormone (JH) (10 μg per insect; JH 1, C 18) in allatectomized females at first stimulates the differentiation of the follicular cells, which occurs normally during the first phase of vitellogenesis; the different structures observed in such oocytes are the same as in untreated insects.