On the innervation of the salt gland

Summary The innervation of the salt gland of the goose, the duck and the swan was investigated by means of electron microscopy. Axonal swellings were observed in relationship to secretory cells as well as to central duct cells. The terminals contain synaptic and densecored vesicles. There are no specialized pre- and postsynaptic membranes.Supported by the Deutsche Forschungsgemeinschaft (Ku 210/4).     

Etude au microscope électronique de la neurohypophyse de Rana esculenta L.

Résumé L'éminence médiane et la pars nervosa de Rana esculenta diffèrent du point de vue de leur structure.L'éminence médiane se compose de 2 zones différentes: la zone externe placée près du lobe distal et la zone interne située sous l'épendyme. Dans la zone externe, on distingue, d'après la taille et la forme des grains de sécrétion, 5 types de terminaisons.1. des terminaisons avec de fins granules sphériques denses de 800 à 1000 Å de diamètre; 2. des terminaisons avec des granules de 1000 à 1200 Å de diamètre; 3. des terminaisons avec des grains de forme irrégulière de diamètre supérieur aux précédents (1200 à 1600 Å); 4. des terminaisons avec de volumineux grains denses sphériques d'environ 1200 à 1800 Å de diamètre; 5. un petit nombre de terminaisons ne contenant que des vésicules. Les terminaisons des catégories 3 et 4 sont probablement du type neurosécrétoire.La zone interne contient de nombreuses fibres neurosécrétrices. Elles sont de 2 types, l'une avec de gros granules (1600–2400 Å), l'autre avec des granules moins volumineux (1300–2000 Å). Des fibres non neurosécrétrices ont également été observées.Dans la pars nervosa, on rencontre deux types principaux de fibres neurosécrétrices, l'une avec des grains denses de 1600 à 2400 Å de diamètre, l'autre avec des grains moins denses d'environ 1300 à 2000 Å de diamètre. Dans la zone externe bordant la pars intermedia des fibres aminergiques avec de fines granulations ont été observées.

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Electron microscopic study of the neurohypophysis of Rana esculenta L.

Summary The median eminence and the pars nervosa of Rana esculenta have a different structure.The median eminence has 2 different zones: the outer zone situated near the pars distalis and the inner zone under the ependyme. In the outer zone there are, according to the size and the shape of the granules, 5 types of nerve terminals.1. Endings containing spherical fine dense granules of 800 to 1000 Å in diameter; 2. Endings with spherical granules from 1000 to 1200 Å in diameter; 3. Endings with granules of irregular shape which are bigger than the former (1200 to 1600 Å); 4. Endings with spherical dense granules of about 1200 to 1800 Å in diameter; 5. A few endings containing only clear vesicles. Type 3 and type 4 endings are probably neurosecretory.The inner zone contains numerous neurosecretory fibres. They are of two types: one with big granules (1600–2400 Å), the second with smaller granules (1300–2000 Å). Non-neurosecretory fibres have also been observed.The pars nervosa contains two principal types of neurosecretory fibres: one with dense granules of 1600 to 2400 Å in diameter, the other with lighter granules of about 1300 to 2000 Å. In the external zone lining the pars intermedia, aminergic fibres with fine granules have been observed.

Je tiens à exprimer mes vifs remerciements, à Monsieur le Professeur E. Follenius pour l'intérêt constant qu'il prend à ce travail. Je remercie également Madame R. O. Clauss, collaboratrice technique et Madame Schwoerer, photographe, pour leur aide précieuse.     

End plate classification and spontaneous sprouting in the sternocostalis muscle of the rat: A new whole mount preparation

Summary The sternocostalis muscle of the rat provides an ideal preparation for examination of neuromuscular junctions in a whole mount. It contains all three morphological end plate types (A, B and C), and its segmental innervation allows ease of experiment, such as partial denervation.The ratio of end plate types remains constant in all individuals of the same age, and there is no variation in this ratio over different regions of the same muscle. Spontaneous sprouting was observed from end plates of all the animals examined: again the ratio of sprouting end plate types remained constant over all muscles examined, and over all regions of the same muscle.     

Ultrastructure of enterochromaffin cells and associated neural and vascular elements in the mouse duodenum

Summary Enterochromaffin cells of adult mouse duodenum were studied with light- and electron-microscopical techniques. They were distinguished from other enteroendocrine cells by their pleomorphic, electron-dense secretory granules in the basal cytoplasm. At the apices of enterochromaffin cells, tufts of short microvilli bordered the gut lumen. At their bases, irregular cytoplasmic extensions were either in contact with or passed through the basal lamina. The presence of cytoplasmic extensions in close proximity to fenestrated capillaries and subepithelial nerves suggested an endocrine or paracrine function. Electron micrographs of serial thin sections were used to reconstruct an enterochromaffin cell from the crypt epithelium in three dimensions and to determine its relationship with the underlying neural plexus. Although extensions from the serially sectioned and reconstructed cell and other enterochromaffin cells studied in crypt epithelia protruded through the basal lamina, no synaptic contacts were seen. Evidence of a synaptic contact between a neurite and another type of enteroendocrine cell (possibly an intestinal A cell), suggested a neurocrine role for some of the basally-granulated cells. Possible functions of enterochromaffin cells are discussed in the light of recent literature on the system of enteroendocrine cells, also known as APUD (amine precursor uptake and decarboxylation) cells and/or paraneurons.     

The basiepithelial nerve plexus of the viscera and coelom of eleutherozoan echinodermata

Summary The organisation of the basiepithelial nerve plexus in the alimentary canal of a starfish and the water vascular system of a sea-urchin is described. The plexus contains varicose aminergic neurones which terminate adjacent to the ciliated epithelial cells. It is proposed that the basiepithelial plexus innervates these cells and controls ciliary beating. The distribution of the basiepithelial plexus in various tissues described by other workers is dicscussed particularly in relation to whether it is the coelomic epithelium or the luminal epithelium which is innervated. It is concluded that where there is both an endothelium and a coelomic epithelium only one is innervated. The muscles, where present, of the viscera are innervated by a separate nervous system. The muscles are always on the opposite side of the non-cellular connective tissue sheath to the basiepithelial plexus.