Studies on the neurosecretory system of Ranatra elongata fabricius (Hemiptera: Nepidae) with reference to the distal fate of NCC I and II.

Abstract

AbstractWith the help of PF and PAVB bulk‐stained preparations and sections the neurosecretory system of Ranatra elongata has been described. Two medial, each of 9‐10 cells, and two lateral, each of 3‐4 cells, groups of neurosecretory cells have been observed in the protocerebrum. Only the A‐cells have been found to be positive to PAVB histo‐ and cyto‐chemical technique. Axons of the A‐cells after traversing the proto‐ and deuto‐cerebrum emerge from the tritocerebrum as the NCC I. The NCC I after bypassing the corpora cardiaca penetrate the aorta wall. There is no physical continuity between the corpora cardiaca and the NCC I and the two are separable. The NSM from the A‐cells, transported by their nerve fibers, has been observed in the aorta wall. On the basis of large accumulation on NSM in the aorta wall the latter has been considered as the storage‐and‐release organ for the A‐material. Corpora cardiaca are found to be devoid of A‐material. Axons from the B‐cells, after emergence from the tritocerebrum as the NCC II, have been observed to penetrate the corpora cardiaca. On the basis of ample amounts of B‐material the glands have been considered as the storage‐and‐release organ for the B‐material only.Observations are compared with results on related species and it is concluded that two independent organ complexes constitute the neurosecretory systemt of R. elongata. The A‐cells, their pathways, the NCC I, and the aorta wall comprise the first; and the B‐cells, their pathways, the NCC II, and the corpora cardiaca the second. The former is concerned with the elaboration, transportion, storage‐and‐release of the A‐material and the latter with the B‐material. Finally arguments are presented to include the aorta wall in the neurosecretory system.