Innervation des cellules du pancr�as endocrine du Poisson T�l�ost�en Xiphophorus helleri H

Gut endocrine cells in the snail Helix aspersa

A microscopic study of the endocrine cells present in the gut of the snail Helix aspersa is made. Electron microscopy is necessary in most cases to identify the enteroendocrine cells, since neither silver impregnations nor immunocytochemical staining have rendered positive results. Endocrine cells are scarce and rest on the basement membrane. They display a clear cytoplasm and variable amounts of small (143 nm) secretory granules of diverse electron-density. They are ovoid or rounded and possess apical processes which extend into the lumen of the gut. The nucleus, located in the basal region of the cell, presents characteristic cytoplasmic indentations. Intraepithelial nerve bundles in contact with endocrine cells are present.

The role of hormones in the acclimation of fish to low temperatures

The known cases elucidating the role of hormones in the regulation of physiological and biochemical changes which occur when fish are acclimated to low temperatures are sparse, but evidence is accumulating to implicate prolactin, glucagon, insulin and perhaps thyroxine and cortisol in at least some of the physiological adjustments observed in some species. The need for further research on hormonal control mechanisms at work during low-temperature acclimation is discussed, with special emphasis placed on neuroendocrine relationships.

The terminal autonomic nervous system in the pancreas of newts. Electron microscopic investigations using acetylcholinesterase and zinc iodide-osmium tetroxide reactions

The intrinsic innervation in the pancreas of newts Triturus vulgaris, Tr. montandoni and Notophthalmus. All the investigated species display: cholinergic innervation better developed than adrenergic, no qualitative differences regarding the fine structure of nerve fibers and terminals as compared to that previously described in the pancreas or in other glands, axo-axonal contacts. Their functional signification as peripheric synapses is suggested. Frequently neuro-glandular junctions with or without membrane specializations. The occurrence of the latter is discussed in connection with peripheral transmission of nervous impulse.