Pancreatic polypeptide (PP)- and glucagon cells in the pancreatic islet of Xiphophorus helleri h. (Teleostei)

Summary Correlative immunohistochemical and electron microscopical studies on the pancreatic islet of the teleost fish Xiphophorus helleri using antibodies to pancreatic polypeptide (PP) and glucagon show that separate cell types are responsible for the production of these peptides. The PP-cells correspond to the previously described A2-cells with round granules, while the A2-cells with crystalline granules are the true glucagon cells. An earlier suggestion that there are two types of glucagon cells in teleost islets is therefore withdrawn.A portion of the results has been presented at Colloque annuel de la Société Française de Microscopie électronique, Lyon-Villeurbanne, 21–23 Mai 1979. Study supported in part by the Medical Research Council     

The ultrastructure of the cell types in the endocrine pancreas of the horse

Summary The islets of Langerhans of the equine pancreas were examined with the electron microscope after immersion or perfusion fixation. Five cell types could be distinguished after fixation by either technique: 1. A-cells, situated at the center of the islets, 2. B-cells, containing mostly pale granules and constituting the principal cell type of the periphery of the islets, 3. D-cells, also located mainly at the periphery of the islets, 4. G-cells, found at the edge of the islets and in the exocrine pancreas, and 5. S-cells, (small granule cells), which are relatively few in number and occur only in the islets. The function and age-dependent modifications of these cells are discussed. The formation of light and dark cells and of mixed cells are regarded as artifact, since cells of this type occur only under the condition of immersion fixation.Dedicated to Professor Dr. Drs. h.c. W. Bargmann on the occasion of his 70th birthday.     

Ultrastructure of the pituitary gland (pars distalis) in sockeye salmon (Oncorhynchus nerka) during gonad maturation

Summary The fine structure of the various hormone-producing cell types (with the exclusion of the prolactin cells) in the pituitary gland (pars distalis) of migratory sockeye salmon is described. All fish were in an advanced stage of sexual maturation. In the proximal pars distalis five cell types were distinguished: growth hormone cells, ACTH cells, gonadotrops, vesicular cells, and chromophobe cells. Gonadotrops were also found throughout the rostral pars distalis. A conspicuous feature of the gonadotrops was the presence of two kinds of secretory inclusions: small electron-dense granules (200–375 m) and large, relatively electron-translucent globules (400–2 000 m). The large vesicular cells, so called because of their conspicuous vesicular endoplasmic reticulum, were numerous and often appeared to contain some small granules. It is argued that they may represent a second type of gonadotropic cell, which, in earlier stages of gonad development, contains many granules but becomes largely degranulated near the time of reproduction when the other gonadotrops (globular gonadotrops) abound. The chromophobes, which were smaller and far less abundant than the vesicular cells, also appeared to contain small granules (120–280 m). They are probably thyrotrops.The assistance of Mr. S. Killick, of the International Pacific Salmon Fisheries Commission, who helped in the collection of salmon, is gratefully acknowledged.     

Vasoactive intestinal polypeptide-like immunoreactivity in nerves of the pancreatic islet of the teleost fish,Gillichthys mirabilis

Summary In the teleost fish, Gillichthys mirabilis, vasoactive intestinal polypeptide (VIP)-like immunoreactivity is present in some nerve fibres of the principal pancreatic islet and surrounding tissues, the vagus and splanchnic nerves, the coeliac ganglion and the wall of the intestine. The nerves of the pancreatic islet that contain VIP-like immunoreactivity probably correspond to one of the two types of non-cholinergic, non-adrenergic (peptidergic) nerve previously described in this fish. Similarities in the localisation of hormonal peptides in fish and mammals suggest that the regulation of gastroenteropancreatic physiology in fish may resemble that of mammals.This work was supported by grants from the Medical Research Council of Great Britain and the National Institutes of Health, USA (Grant No. AM 17161)     

On argyrophil reactions of endocrine cells in the human fetal pancreas

Summary The endocrine cells in the pancreas of five human fetuses with gestational ages of 18–20 weeks were examined by light and electron microscopy with special regard to argyrophil reactions. B-cells and typical A and D-cells were easily identified electron microscopically on the basis of their typical secretory granules. In the Grimelius argyrophil silver stain, a concentration of silver grains over the less electron dense peripheral mantle of the A-cell secretory granules was observed by electron microscopy. In the Hellerström and Hellman modification of the argyrophil Davenport alcoholic silver stain, silver grains were concentrated over the internal structures of the D-cell secretory granules. With this stain an accumulation of silver grains was also seen at the surface of the A-cell secretory granules. The argyrophil reaction of the A-granules was less pronounced than in the D-cells. In addition to B-cells and A- and D-cells, two other types of endocrine cell were observed by electron microscopy. These cells were argyrophil with the silver impregnation method of Grimelius. The electron microscopic findings at least partly explain the frequent overlapping between the two staining methods observed at the light microscope level.This study was supported by the Swedish Medical Research Council (Project No. 102)     

Studies on the innervation of the endometrium

Summary The innervation of the endometrium of rabbit, rat, mink, mongoose and pig has been investigated electron microscopically. Large bundles of nerve fibers can be observed in the connective tissue spaces within the basal layer of the endometrium. Unmyelinated nerve fibers enter the lamina functionalis, terminal nerve fibers penetrate the basal lamina and make contact with the glandular and the cavum epithelial cells. The terminal axons contain abundant synaptic vesicles, dense core vesicles and mitochondria. To date, no specialized presynaptic or postsynaptic membranes have been found.Supported by the Deutsche Forschungsgemeinschaft, Bonn-Bad Godesberg (Grants Ku 210/5 and Be 524/4).Dedicated to Prof. Dr. Drs. h.c. Wolfgang Bargmann on his 70th birthday in friendship and admiration.     

The fine structure of the pancreatic nerves of the domestic fowl

Summary The fine structure of the pancreatic nerves of the domestic fowl has been studied. Naked axon beadings were found in membranous contact with endocrine as well as exocrine cells. From an anatomical point of view it seems reasonable to suggest that the endocrine glands might be subjected to some influence of the autonomic nervous system.     

Light and electron microscopic investigations of six types of glandular cells of the bovine adenohypophysis

Summary Twelve bovine adenohypophyses were prepared for light and electron microscopy of the cell types of pars distalis. Correlation between the light and electron microscopy was effected by use of alternate thin and thick sections. Cytological changes in the experimental animals were used as criteria for the identification of six different types of secretory cells.Two types of acidophils, alpha and epsilon cells, are recognized in peripheral area of the pars distalis by light and electron microscopy. The alpha cells contain orangeophilic secretory granules of a maximum diameter of 400–450 m and correspond to ordinary acidophils (STH cells). The second type, epsilon cells, contains larger, fuchsinophilic granules of 600 to 900 m in diameter, increase in number and granulation after pregnancy and thyroidectomy, and are thought to be prolactin cells (LTH cells).Two types of amphophils, zeta and delta 1 cells, were found in the central area of the pars distalis. The zeta cells contain smaller numbers of amphophilic, cored granules (200 m maximum diameter) and based on the comparison with literature on other species of animals, are designated as ACTH cells. The delta 1 cells are round or oval and contain very dense, spherical granules (250–300 m) which are stained red or reddish purple with PAS, aldehyde thionin and PAS-methyl blue methods. They show extreme enlargement and bizarre cytoplasmic appearance after castration and are designated tentatively as LH gonadotrophs or LH cells.Two types of basophils, beta and delta 2 cells, were also identified by correlative light and electron microscopy. The beta cells are polygonal in outline, distributed exclusively in the zona tuberalis and contain large, less dense secretory granules (300–400 m) which are stained selectively with Gomori's aldehyde fuchsin. After thyroidectomy, they lose their secretory granules and are transformed into large, vacuolated thyroidectomy cells. They are therefore, identified as thyrotrophs or TSH cells. The delta 2 cells are round, oval or polygonal in shape and contain basophilic granules ranging from 220 to 300 m in diameter. They show extreme enlargement and vacuolization due to the dilation of endoplasmic reticulum, after castration, and are designated tentatively as FSH gonadotrophs or FSH cells.The investigation reported herein was supported by a Scientific Research Grant (No. 291049) from the Ministry of Education of Japan.     

The fine structure of the stomach mucosa of the llama (Llama guanacoe)

Summary The epithelium of the fundic region mucosa of the hind stomach in the Llama guanacoe has been studied using morphological and histochemical methods. Morphology suggests that solute and water absorption may occur in the epithelium of the surface and of the foveolae, although this absorption can not be estimated because of the extensive secretion of the gastric glands. The same cells of the surface and foveolar epithelium show numerous secretory granules. The glands reveal neck cells, chief cells, a large number of oxyntic cells, four types of endocrine cells (A-like, ECL, D and EC), brush cells and wandering cells. PAS and Alcian blue reactions for light microscopy suggest a secretion of neutral and acidic mucosubstances in the surface and foveolar epithelium, of neutral mucosubstances only in the neck cells. Periodic acid-thiocarbohydrazide silver proteinate (PA-TCH-SP) reaction for electron microscopy confirms the presence of neutral mucosubstances within the secretory granules of the surface, foveolar and neck epithelial cells. In all these cells, the reaction product is also evident within sacculi and vesicles of the maturing surface of the Golgi apparatus. A positive PA-TCH-SP reaction also occurs on the membrane (and not on the contents) of the Golgi apparatus (maturing surface) and of the secretory granules of the chief cells as well as on the membrane of the Golgi apparatus and of apical vesicles and tubules of the oxyntic cells. In addition, silver granules slightly enhance the electron density of the contents of the secretory granules in the endocrine cells. Morphological and histochemical findings are discussed and compared with results described by others for monogastric mammals.     

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).     

Innervation of skin glands in the frog

Summary A comparative study was undertaken on the innervation of mucous and granular glands in frog skin. Results obtained by the Falck-Hillarp fluorescence technique and cholinesterase staining indicated that both types of glands receive exclusively adrenergic innervation. Electron microscopy was used to investigate the innervation pattern at the ultrastructural level. The distribution of nerve terminals was found to differ in the two types of glands. In the mucous gland, terminals were found at a distance of about 0.5 m from the basement membrane but never within the gland parenchyma. In the granular gland, the terminals were located between smooth muscle cells and also in direct contact with the secretory epithelium but never outside the basement membrane.This work was carried out in part at King Gustaf V:s Forskningsinstitut, Stockholm, and was supported by a grant from Karolinska Institutet     

Ultrastructural duality of extrafusal fibers in a slow (tonic) skeletal muscle

Summary Ultrastructural and stereological assessment of the mature avian anterior latissimus dorsi (ALD) muscle showed that it contains two kinds of extrafusal fibers. This fine structural dichotomy of fiber types in the ALD correlated well with their previously reported histochemical duality. Distinct differences occur in sarcomere banding, myofibrillar area, sarcotubular and mitochondrial density, and in morphology of motor-nerve terminals. Both myofiber types in this muscle were interpreted as representing varieties of slow or tonic muscle fibers.Both fibers contain myofibrils that, despite differences in cross-sectional area, were large, irregular, and ribbon-shaped, typical of the Felderstruktur appearance of true slow fibers. Whereas the majority of fibers (type-1) are devoid of well-defined M-bands, the minor fiber population (type-2) exhibit prominent M-bands in the center of each sarcomere. In addition, type-1 tonic fibers contain a significantly lower mitochondrial and sarcotubular volume than the tonic fibers of type-2. While both fiber types exhibit motor-nerve terminals that are small, smooth and punctate in appearance, those on the type2 fibers often had a number of shallow postjunctional folds. Whether or not these two classes of extrafusal fiber in this muscle represent two separate and distinct types of motor units remains to be determined functionally.Supported by grants from the Medical Research Council and the Muscular Dystrophy Association of Canada. The author gratefully acknowledges the excellent technical assistance of Susan L. Shinn     

Ultrastructure of spermiogenesis and spermatozoa of Gymnotus cf. anguillaris and Brachyhypopomus cf. pinnicaudatus (Teleostei: Gymnotiformes)

The ultrastructure of spermiogenic stages and spermatozoa of representatives of two gymnotiform families, Gymnotus cf. anguillaris (Gymnotidae) and Brachyhypopomus cf. pinnicaudatus (Hypopomidae) were studied. Spermiogenesis of both species is characterized by lateral development of the flagellum and formation of a nuclear fossa. Some differences were found between these species, such as whether (B. cf. pinnicaudatus) or not (G. cf. anguillaris) nuclear rotation occurs, permanence of the cytoplasmic channel, and type and localization of the nuclear fossa. In the G. cf. anguillaris spermatozoon the nucleus is spherical with highly condensed chromatin. The nuclear fossa is shallow and lateral and is associated with the centriolar complex through stabilizing fibrils. The midpiece is short, with many vesicles, a cytoplasmic channel, and elongate mitochondria. In the B. cf. pinnicaudatus spermatozoon the ovoid nucleus is elongated lateral and posterior to the centriolar complex, and has highly condensed chromatin. The eccentric nuclear fossa is of the moderate type, and contains the entire centriolar complex. The midpiece is long, with numerous vesicles, elongate mitochondria, and no cytoplasmic channel. In both species the flagella are laterally disposed in relation to the nucleus and comprise of the classical 9+2 axoneme. Most of the characteristics found in the spermatozoa of these two species of Gymnotiformes are shared with species of Characiformes, whereas only a few are also found in Siluriformes. This suggests that Gymnotiformes and Characiformes may be more closely related than previously proposed.     

Ultrastructural observation of possible nerve endings in rat sebaceous gland

Summary Neural elements within the parenchyma of the sebaceous gland have not been reported previously. Nerve endings have been observed only in the connective tissue surrounding the gland or in close association with the undifferentiated basal cells.In this study, electron microscopy revealed the possible presence of nerve endings (or terminal portions of neural elements) in the suprabasal level of functional sebaceous glands of pinnae of white rats. Morphologically, there are two distinct types of nerve endings. Type 1 is bordered by a membrane of relatively irregular contour and contains a single mitochondrion, various-sized vesicles, numerous microtubules, fine neurofilament-like fibrils, and occasional ribosome-like granules. Type II is also bordered by a membrane, but its contour was relatively smooth and rounded. Moreover, Type II contains many mitochondria, varying in size, density, and the arrangement of cristae. While ribosome-like granules are scattered throughout the structure in relative abundance, there are scarcely any fine neurofilament-like fibrils or microtubules. Whether these two structures are sensory or autonomic fibers could not be determined by electron microscopic examination.     

Development of the innervation in the human pineal organ

Summary This investigation is concerned with pineal organs of human embryos 60 to 150 days old. At every stage central nerve fibres enter the pineal organ by way of the habenular commissure, but are restricted to the pineal's proximal part. On about the 60th day of the development the sympathetic nervus conarii grows into the distal pole of the pineal organ from a dorso-caudal direction and plays the predominant part in the innervation of the pineal organ. After penetrating, it soon branches out and forms a network in the pineal tissue. Much later, not until the 5th embryonic month, sympathetic nerves appear accompanying the supplying vessels in the perivascular spaces. After a short time these nerves pierce the outer limiting basement membrane and penetrate the parenchyma. Towards the end of the 5th embryonic month the axons of the sympathetic nerves form varicosities containing clear and dense core vesicles. At this point large amounts of laminated granules appear primarily in cell processes, probably of pinealocytes. Isolated granules also occur in the varicosities of axons. The granules encountered here are most likely secretory granules.Dedicated to Professor Bargmann on his 65th birthday.     

Observations on the fine structure,enzyme histochemistry,and innervation of parathyroid gland and ultimobranchial body of Chthonerpeton indistinctum (Gymnophiona,Amphibia)

Summary Fine structural and enzyme histochemical observations on ultimobranchial body and parathyroid gland of the caecilian Chthonerpeton are presented. The cell clusters and follicles of the ultimobranchial body consist mainly of granulated cells which are termed C-cells and obviously belong to the APUD cell series. In the larger follicles additional possibly exhausted degranulated cells and replacement cells occur. A rich supply of nerve fibres has been found in this gland. Frequently nerve terminals were observed to come into synaptic contact with the C-cells. Two categories of nerve fibres occur: a) fibres containing large polymorphic electron dense granules (probably purinergic fibres), b) fibres containing small electron transparent vesicles and a few electron dense granules (probably cholinergic fibres). The parathyroid gland consists of elongated cells (one cell type) poor in organelles and often containing fields of glycogen and lipid droplets. The cells are further characterized by fair amounts of lysosomal enzymes; they are interconnected by maculae adhaerentes and occludentes. No nerves and blood vessels have been found in the parathyroid gland of Chthonerpeton. This study has been supported by the Deutsche Forschungsgemeinschaft We 380/5.     

Über Arthropoden-Abwehrstoffe. LVIII Zur Feinstruktur der Pygidialdrüsen des Gelbrandkäfers (Dytiscus marginalis L., Dytiscidae,Coleoptera)

Zusammenfassung Die Pygidialdrüsen von Dytiscus sezernieren eine Emulsion, die p-Hydroxybenzaldehyd, p-Hydroxybenzoesäuremethylester, Benzoesäure und ein Glycoproteid enthält. Ihre Loben sind aus zwei verschiedenen Arten von Drüsenzellen aufgebaut, den Kanalzellen, die die Einzelkanäle und den Sammelkanal umgeben, und den Tracheoblasten. Die chitinigen Einzelkanäle enden mit einer traubigen oder blasigen Anschwellung, die aus einer massiven inneren und einer schwammigen äußeren Wandschicht besteht, in einer Höhle der sekretorischen Zellen. Die Zahl der Blasen - und Trauben-Zellen ist etwa gleich. Die zentrale Höhle ist von Mikrovilli umgeben, die durch Mikrofibrillen in hexagonaler Packung ausgesteift werden. Wie die Untersuchung nach Gefrierätzung zeigt, ist die konvexe Seite der Mikrovilli-Membran dichter mit Partikeln besetzt als die konkave Seite. Beide Zelltypen haben ein ausgedehntes tubuläres glattes endoplasmatisches Reticulum; freie Ribosomen und granuläre Zisternen sind selten. In den Traubenzellen ist der Golgi-Apparat besser als in den Blasenzellen entwickelt. Die zentrale Höhle der Traubenzellen enthält eine fein-flockige Substanz, die der Blasenzellen ein dichtes osmiophiles Material. Die Sekretionsmechanismen, die Beteiligung verschiedener Typen von Vesikeln und anderer Zellorganellen an der Sekretion und die Unterschiede zwischen den beiden Drüsenzelltypen werden diskutiert. Es wird angenommen, daß die Hauptkomponenten des Sekretes eccrin ausgeschieden werden.

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On defense substances of arthropods LVIII the fine structure of the pygidial glands of the water beetle, Dytiscus marginalis L.

Summary The pygidial glands of Dytiscus secrete an emulsion containing p-hydroxybenzaldehyde, p-hydroxybenzoate, benzoic acid, and a glycoproteid (Schildknecht, 1970). Their lobes are composed of two different types of secretory cells, channel cells (which surround a channel, draining the secretory cell, as well as the collecting channel), and of tracheoblasts. The chitinous draining channel ends in the form of either a racemous or a bulbous swelling consisting of a massive inner and a spongy outer wall layer in a cavity of the secretory cell. The number of racemous and bulbous cells is nearly the same. The central cavity is surrounded by microvilli which are stiffened by microfibrils in a hexagonal packing. After freeze etching the convex surface of the microvilli reveals more membrane particles than their concave surface. Both cell types have an extended smooth surfaced tubular endoplasmic reticulum; the amount of free ribosomes and of granular cisternae is low. In the racemous cells the Golgi apparatus is better developed than in the bulbous cells. In the racemous cells the central cavity contains a fine-fluffy substance, in the bulbous cells a dense osmiophilic material. The mode of secretion, the participation of various kinds of vesicles and other cell organelles in this process, and the differences between the two types of secretory cells are discussed. It is assumed that the main components of the secretion are released in the eccrine way.

Wir danken der Deutschen Forschungsgemeinschaft für Sachbeihilfen.