Studies on the neursecretory system of the female mole cricket Gryllotalpa africana (Orthoptera: Gryllotalpidae)

Abstract

The neurosecretory system of the mole cricket Gryllotalpa africana Beauvois, using PF and PAVB techniques, has been described in detail. Two types of cells, A‐ and B‐cells, have been observed. While the A‐cells are present in the pars intercerebralis medialis the B‐cells are distributed in the pars intercerebralis medialis and lateralis. On the basis of differences in size and appearance A‐cells have been subdivided into two, A1‐ and A2‐subtypes. Six stages for the accumulation of NSM in the A1‐cells have described. The variations in the shape of A1‐cells and reduction in their sizes have been correlated with the physiological state of the cells. The formation of the median neurosecretory pathways by the convergence of the proximal portion of the axons of A1‐cells, their crossing over and their emergence from the ventral side of the protocerebrum as the NCC I have been demonstrated convincingly. The NCC 11, reported for the first time in the mole cricket, joins the NCC I shortly behind the protocerebrum. Each common NCC joins the corpus cardiacum of its side apically and its nerve fibres penetrate the gland in a fan‐like fashion. The state and appearance of the NSM aggregates under transport, from the centre of elaboration to its storage centre, are described. The NSM is stored in the entire corpus cardiacum larger amounts being concentrated along the aorta wall and in the posterior half of the gland. The possibility of elaboration of NSM in the cells of the corpora cardiaca has been considered. A commissure, ventral to the aorta and posterior to the hypocerebral ganglion, joins the corpora cardiaca, through which passage of NSM occurs. In mature females, in contrast to the immature ones, the number of A‐cells containing the SM is greater, the amount of NSM in the cells is larger and the number of their activity cycles is greater. From these features, and from the presence of larger amounts of NSM in the corpora cardiaca it is inferred that the neurosecretory system of mature female is more active than those of the immature females.