STUDIES ON THE NEUROSECRETORY SYSTEM OF IPHITA LIMBATA STAL. I. DISTRIBUTION AND STRUCTURE OF THE NEUROSECRETORY CELLS OF THE NERVE RING

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Abstract
In Iphita limbata (Pyrrhocoridae: Hemiptera) the brain contains paired medial and lateral groups of neurosecretory cells, and the subesophageal ganglion scattered marginal neurosecretory cells. The medial cells (pars intercerebralis) number about 16 on each side, the lateral 3 or 4. On the basis of their staining properties, 2 types of neurosecretory cells can be distinguished in the nerve ring of Iphita. "A cells" staining a deep blue with Gomori''s chrome-hematoxylin-phloxin and a bright red with Azan make up most of the neurosecretory cells of the brain. The subesophageal ganglion contains "B cells," staining red with Gomori''s method and light blue with Azan. The corpora cardiaca and their nerves (nervi corporis cardiaci) contain a material similar in its staining properties to that of the "A cells." The medial neurosecretory cells of the protocerebrum contain large nuclei with a low, and nucleoli with a higher, refractive index. The nucleoli are phloxinophilic and azocarminophilic. The cytoplasm contains granules and spheroids. The granules appear black in the phase contrast microscope, violet with dahlia and, like mitochondria, red with acid fuchsin; they exhibit continual Brownian movement in the living cells. The granules are associated with a fluid material. The spheroidal system which is osmiophilic, argentophilic, and sudanophilic, represents the lipochondria. Both the granular and spheroidal systems are revealed by supravital staining methods. Cytoplasm of the neurosecretory cells contains a high concentration of ribose nucleic acid. Nuclear membrane and the cytoplasm show granular concretions of vitamin C. The secretory material contains proteins as indicated by various tests. The granular and spheroidal constituents are rich in phospholipines. Tests for chromaffin substances and glycogen gave negative results. Staining methods for lipofuscins shown that the product in the "A cells" probably contains these very complex substances.