Neurosecretory cells and aorta as neurohaemal organ in the earwig, Euborellia annulipes lucas (Dermaptera : Labiduridae)

Abstract

The neurosecretory system and retrocerebral-endocrine-aortal-complex of Euborellia annulipes have been described using performic acid resorcin fuchsin (PARF) and performic acid victoria blue (PAVB) techniques. There are 2 medial groups of neurosecretory cells (MNC). Each of them consists of compactly arranged 10–14 A-cells and a small number of B-cells. The axons of MNC, on each side of the brain lobe, converge at a point, and form a medial neurosecretory pathway (NSP). The 2 pathways, formed in this manner, decussate posterior to the corpus centrale, and run separately behind the brain. From the latter, they emerge as nervi corporis cardiaci—I (NCC—I) that enter the cephalic aorta (AO). Thus, the neurosecretory material (NSM) of the medial neurosecretory cells (A and B) transported via NCC—I is stored in the cephalic aorta (AO). The latter is packed with abundant NSM in mature earwings. Lateral sides of the brain contain a few B-cells. The B-cell secretion is transported to the corpora cardiaca (CC) through nervi-corporis cardiaci—II (NCC—II). Thus, CC store secretions of lateral cells and the products of their own chromophil cells. Corpora cardiaca are 2 elongate bodies composed of 2 types of cells. Although, the aorta is associated with the CC, migration of A-cell NSM from AO to CC was not observed. The corpus allatum (CA) is a globular body whose anterior part is attached with the posterior parts of the CC, and the dorsal surface associated with the ventral wall of the aorta. The gland consists of only one type of parenchymal cells. Migration of A-cell NSM from AO to CA is not observable.