Hypocerebral Ganglion Research Articles

THE CEPHALIC NERVOUS SYSTEM OF ADELPHOCORIS LINEOLATUS (GOEZE) (HEMIPTERA : MIRIDAE)

The morphology of the cephalic ganglia and their main nerves in Adelphocoris lineolatus (Goeze), including the sympathetic system of the head and the retrocerebral complex, is described and figured, and compared with that of Liocoris unctuosus Kelton. There are only two ganglia in the ventral chain; the suboesophageal and prothoracic ganglia make up one unit; the meso- and meta-thoracic and all the abdominal ganglia and, fused into a common mesothoracic center, make up the second. The major nerve branches from these centers are also described. A distinct branch, the "nerf laterale," from the suboesophageal–prothoracic ganglion to the corpora paracardiaca, was seen. This ganglion also innervates the thoracic glands. The sympathetic system of the head includes the frontal ganglion and its connectives, a single recurrent nerve, the hypocerebral ganglion, and an unpaired oesophageal nerve. The corpora paracardiaca are paired and are closely applied to the anterior surface of the unpaired corpus allatum.

Secretory Structures associated with the Neurosecretory System of the Immature Scorpion, Heterometrus swammerdami

ABSTRACT Certain previously unknown structures, probably endocrine in nature, are described. The blind ‘end-organ’ which is present and shows signs of activity in the pre-moult stage shows no noticeable sign of activity in the post-moult stage. In certain respects it is comparable to the ‘anterior organ’ of spiders, which has been homologized with the prothoracic glands of insects. In the rostral region of the scorpion, where the rostral nerve ramifies, an accumulation of leucocytes is found; these show signs of secretory activity. Both at the origin of the rostral nerve and also where it ramifies, neurosecretory material is seen. This rostral structure is comparable in certain aspects with the rostral organ of spiders. Leucocytes occur not only in the rostral organ but also in association with the ‘endorgan’. The presence of two ganglionic masses, above and below the stomodaeal commissure, suggests the possibility of the sympathetic (stomatogastric) ganglion of the scorpion being a composite structure consisting of the frontal ganglion, the corpus cardiacum, and possibly the hypocerebral ganglion. A hypocerebral ganglion is absent in the adult.

GROSS ANATOMY OF THE NERVOUS SYSTEM AND RETROCEREBRAL COMPLEX OF ADULT LIOCORIS UNCTUOSUS KELTON (HEMIPTERA:MIRIDAE)

The gross anatomy of the central nervous system and retrocerebral complex of adult Liocoris unctuosus is described and figured. There are three ventral ganglia; the suboesophageal and first thoracic ganglia are separate, while the second and third thoracic are fused with the abdominal ganglia into a common center. Innervation of the reproductive organs in the male is described. The retrocerebral complex consists of the hypocerebral ganglion, paired corpora paracardiaca, and a single corpus allatum, and their associated nerves.

Studies on the neurosecretory system of Iphita limbata Stal. (Hemiptera). III. The endocrine glands and the neurosecretory pathways in the adult.

1. The neurosecretory cells of the pars intercerebralis of the brain of Iphita limbata Stal. (Pyrrhocoridae: Hemiptera) number sixteen on each side. Their axons after forming a ‘chiasma’ run ventralwards and posteriorwards to emerge out as the cardiac nerves to the corpora cardiaca and then run on as the median allatic nerve to the corpus allatum. 2. Granular neurosecretory matter is transported along these axons to the corpora cardiaca which are discernible among the cells of these glands. The cells of the corpora cardiaca show a secretory product which appears to be different from the neurosecretory material. 3. Granules and larger colloids are seen transported along the allatic nerve into the corpus allatum. 4. The recurrent nerve emanating from the hypocerebral ganglion in contact with the corpora cardiaca and the allatic nerve also contain neurosecretory colloids along their axons. 5. Neurosecretory colloids also pass into the aorta through the wall at the anterior end which region is invested laterally and ventrally by the cardiac-allatum system.

The Morphology and Physiology of the Salivary Glands of Hemiptera-Heteroptera

ABSTRACT The salivary glands of the Heteroptera consist of a pair of primarily bilobed principal glands and accessory glands which vary very greatly in form and structure in different families. The glands are usually supplied with tracheae, and the principal glands are invested by a nervous plexus which is supplied by a glandular nerve from the hypocerebral ganglion of the stomatogastric system. The principal salivary gland of Notoneeta is characterized by the presence of large cells having zymogen granules and by the storage of fluid secretion in vacuoles. In contrast, most of the remaining Heteropteran salivary glands belong to the vesicular type, having a one-layered glandular epithelium made up of small cells which discharge their secretion into a large central storage cavity or axial canal. This type of gland lacks zymogen granules but has small dense masses of reserve material in the basal or outer parts of the cells. There is normally no difference in the structure of the glandular epithelium in the different lobes. The accessory glands are either in the form of a thin-walled bladder-like vesicle, or are tubular or duct-like ; they seem to be purely a development of the primary conducting glandular system, and are thus homologous with the salivary reservoir of other orders. All the information obtained in this work is strongly against the idea that the various lobes of Hemipterous salivary glands produce widely different chemical substances, each with a special function. The results obtained by Fauré-Fremiet have not been confirmed. Except with blood-sucking forms digestive enzymes were always found in the glands, two enzymes being the maximum number found in any particular gland. The enzymes were found to be always related to the type of food consumed, and were those concerned with the digestion of that particular component of the food which was present in the greatest proportion. In no case was a cellulase found. An anti-coagulant principle was found to be present in the glands of blood-sucking forms. The accessory glands appear to produce only a watery secretion, enzymes being absent. The pH of the principal gland is generally slightly acid, while that of the accessory gland is neutral. Mitochondria and Golgi bodies typical of insect tissue are present in certain glands, but show no relation to the secretion granules, and thus do not appear to contribute to secretion synthesis. From a number of experiments it appears that the action of the digestive enzymes is not sufficiently rapid for external digestion to take place to any great extent. It seems, however, certain that quite an appreciable quantity of the injected saliva is imbibed again, and that the salivary digestion continues in the stomach, where the food taken in is first stored. The pH activity range of the enzymes is in general wide.