Neurosecretion in the milkweed bug, Lygaeus pandurus scop. (Heteroptera: Lygaeidae)

Neurosecretory cells in the brain, ventral ganglia, and retrocerebral endocrine glands aortal complex of a milkweed bug, Lygaeus pandurus Scop. have been described using a variety of techniques in whole mounts and sections. Two main types of neurosecretory cells viz. A and B types, have been distinguished on the basis of histochemical and staining properties. The A-type of cells have been further divided into 4-sub types viz. A-1, A-2, A-3 and A-4 on the basis of staining properties and cell size. There are only one type of B-cells. The brain and all the ventral ganglia contain neurosecretory cells including the frontal ganglion. The brain consists of A-1, A-2 and B-cells, the suboesophageal and prothoracic ganglia have A-2, A-3 and B-cells, and the lat ganglion have A-2 and B-cells. The frontal ganglion contains only A-4 type of cells. The corpora cardiaca are ovoid bodies consisting of large and small chromophil cells. The chromophil cells are positive to PF and PARF but negative to PAVB. In addition to the secretions of the chromophil cells, the gland also acts as storage organ for lateral, ventral, posterior and anterior neurosecretions of the brain. The corpus allatum which is an unpaired globular epitheloid body, lies behind the corpora cardiaca. It consists of one type of cells. The gland is devoid of A-1 cell NSM i.e. Victoria blue positive material. At times, it shows a small amount of A-2 cell NSM. The aorta which receives the axons of NCC-I is provided with a large amount of neurosecretory material, elaborated in the medial neurosecretory cells of the brain. Thus, in Lygaeus pandurus aorta and not the CC, functions as NHO for medial neurosecretions.