Maintenance of regionally specific patterns of cell proliferation and differentiation in transplanted skin and oral mucosa

Summary Specimens of mouse ear, footpad and tail skin and palatal, buccal and lingual mucosae were transplanted to protected sites prepared in histocompatible hosts either as intact tissues or recombined after separation of epithelial and connective tissue components using EDTA. Despite maintenance in a protected ectopic site for up to 9 weeks, transplants maintained regionally specific differences in histological appearance and rates of mitotic activity. A diurnal variation in mitotic activity comparable to host control tissues was reestablished.This work was supported by NIH/NIDR Grant 1R01DEO5190.     

The development of the stomach in Clarias lazera and the intestinal absorption of protein macromolecules

Summary The development of the stomach of the teleost, Clarias lazera, during the early posthatching period, is described, and the developing stomach is compared with that of adult Clarias.The stomach develops in two distinct parts: the corpus, which differentiates first, and the pylorus. The corpus contains a mucous surface epithelium, arranged in folds, and a tubular gland system containing only one type of gland cell, to which the secretion of pepsinogen and HCl is attributed. The pyloric region does not contain tubular glands.From the ultrastructure of the gland cells, the ³H-thymidine labeling index, and the onset of acid production (as determined with pH indicators) it is concluded that a functional stomach is present in juveniles with a standard length of ± 11 mm (approximately 12 days after fertilization at 23–24° C).The ultrastructure of the intestinal epithelium has also been studied. The intestine consists of three segments, similar to those described for stomachless teleosts and a number of fish larvae. In larvae as well as in juveniles, the enterocytes of the second segment show pinocytosis of horseradish peroxidase, although in the juveniles the stomach has already developed. This second segment has the same relative length in all studied larvae and juveniles and is also present in adult Clarias.It is therefore concluded that the capacity to absorb protein macromolecules is not specifically related to the absence of a functional stomach in this teleost species.     

Autophagie in den Drüsenzellen des Magens bei jungen Mäusen

Zusammenfassung Autophagische Prozesse in verschiedenen Drüsenzellen des Magens neugeborener bis 8 Tage alter Mäuse wurden elektronenmikroskopisch untersucht. Es zeigte sich dabei, daß die intrazellulären Abbauprozesse in jeder Zellart typisch verlaufen. In den mukoiden Nebenzellen findet man große autophagische Vakuolen mit zahlreichen Mitochondrien, in denen beträchtliche Cytoplasmaregionen sequestriert sein können. Stärker abgebaute Mitochondrien liegen oft im Drüsenlumen oder in den interzellulären Räumen. Anscheinend wird der Inhalt autophagischer Vakuolen in sie ausgeschieden. Alle Zellen mit Autophagosomen enthalten gleichzeitig viele und formenreiche Lysosomen. Einige abgenutzte Zellen des mukoiden Oberflächenepithels scheinen durch Heterophagie abgebaut zu werden. In kleinen Autophagosomen dieser Zellen findet man nur einzelne Organellen. In den Belegzellen ist die Autophagie viel seltener. Typisch für die Belegzellen sind stark osmiophile multivesikuläre Körperchen, die sehr wahrscheinlich Lysosomen verkörpern. In den Hauptzellen, die erst nach der Geburt ausdifferenziert werden, trifft man nur ausnahmsweise sequestrierte Zellpartien.Die Ergebnisse werden unter Berücksichtigung von Beobachtungen anderer Autoren, die die intrazellulären Abbauprozesse analysierten, und eigener früher erzielter Resultate diskutiert.

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Autophagy in gastric gland cells of young mice

Summary Autophagy in different gastric gland cells of newborn till 8 days old mice were studied electronmicroscopically. Intracellular digestion goes on in a way typical for each cell type. In the mucous neck cells, big autophagic vacuoles occur in which a large part of cytoplasm with numerous mitochondria is separated. The damaged mitochondria lie very often in the gland lumen or in the intercellular space. It seems, that the contents of autophagic vacuoles can be extruded in these places. All cells with autophagic vacuoles contain also numerous lysosomes of different shape. Some involuted mucous cells of the surface epithelium seem to be digested in a heterophagic process. Autophagy does not appear often in parietal gastric cells. The autophagosomes of these cells are small, and they contain only some organelles. Typical for these elements are osmiophilic multivesicular bodies, probably lysosomes. Chief cells, that differentiate only after birth, have autophagic vacuoles, but seldom. The results are discussed in comparison with results of other authors that worked on the problems of intracellular digestion.

Der Jugoslawischen Forschungsgemeinschaft Savezni Fond (Belgrad) und Sklad Borisa Kidria (Ljubljana) danken wir für finanzielle Unterstützung, Frau B. Zorman und Herrn F. Kovai für technische Hilfe.     

An apparatus for sampling gut contents of large,living fishes

Synopsis Apparatus and methods are described and illustrated for flushing and retaining gut contents from large, living fishes with water supplied by a 12 volt portable pump.     

A gene expression fingerprint of mouse stomach ECL cells

Many of the endocrine cells in the stomach are poorly characterized with respect to physiological significance. In some cases, the anticipated hormone has not yet been identified. Global gene expression analysis of mouse stomach was performed in an attempt to identify the ECL-cell peptide/protein. Specific functional activation (omeprazole-induced hypergastrinaemia) was used as a tool to generate a gene expression fingerprint of the ECL cells. The proposed fingerprint includes 14 genes, among them six are known to be expressed by ECL cells (=positive controls), and some novel ones, which are likely to be ECL-cell-related. The known ECL-cell-related genes are those encoding histidine decarboxylase, chromogranin A and B, vesicular monoamine transporter 2, synaptophysin, and the cholecystokinin-B receptor. In addition, the fingerprint included five genes, which might be involved in the process of secretion and three ESTs with unknown function. Interestingly, parathyroid hormone-like hormone (Pthlh) was identified as a candidate ECL-cell peptide hormone.     

Genetic host factors in Helicobacter pylori-induced carcinogenesis: Emerging new paradigms

Helicobacter Pylori is a gram negative rod shaped microaerophilic bacterium that colonizes the stomach of approximately half the world's population. Infection with c may cause chronic gastritis which via a quite well described process known as Correas cascade can progress through sequential development of atrophic gastritis, intestinal metaplasia and dysplasia to gastric cancer. H. pylori is currently the only bacterium that is classified as a class 1 carcinogen by the WHO, although the exact mechanisms by which this bacterium contributes to gastric carcinogenesis are still poorly understood. Only a minority of H. pylori-infected patients will eventually develop gastric cancer, suggesting that host factors may be important in determining the outcome of H. pylori infection. This is supported by a growing body of evidence suggesting that the host genetic background contributes to risk of H. pylori infection and gastric carcinogenesis. In particular single nucleotide polymorphisms in genes that influence bacterial handling via pattern recognition receptors appear to be involved, further strengthening the link between host risk factors, H. pylori incidence and cancer. Many of these genes influence cellular pathways leading to inflammatory signaling, inflammasome formation and autophagy. In this review we summarize known carcinogenic effects of H. pylori, and discuss recent findings that implicate host genetic pattern recognition pathways in the development of gastric cancer and their relation with H. pylori.     

Postnatal development of mucosa-associated lymphoid tissues in chickens

Summary The postnatal development of chicken mucosa-associated lymphoid tissues of the eyes, lungs, and intestines were investigated with monoclonal antibodies specific for either all leucocytes, B lymphocytes, mononuclear phagocytes, IgM, IgG, or IgA. Attention has been paid to the relation of lymphoid infiltrates with their surrounding mucosae, the segregation into B-cell and T-cell areas, development of germinal centers, and secretory immunoglobulins. Abudant secretory IgM and IgA was detected in the epithelium of the Harderian glands in the orbits, even though they lacked large leucocyte infiltrates with germinal centers. Lymphoid tissues in the mucosae of lungs and intestines developed separate B-cell and T-cell areas. The proventriculus, Meckel's diverticulum, and Peyer's patches generally contained germinal centers from 12 weeks of age on. Because chickens as young as 2 weeks old had germinal centers in bronchus-associated lymphoid tissue and cecal tonsils, these areas were probably highly stimulated by antigens. Isotype-specific monoclonal antibodies were used to detect IgM-, IgG-, and IgA-bearing follicular cells in the same germinal center.     

Specific localization of hepatic fatty acid-binding protein in the gastric brush cells of rats

Summary An immunocytochemical study by light- and electron microscopy using the antibody against rat hepatic fatty acid-binding protein (FABP) revealed the brush cells in the gastric epithelium of rats to be intensely immunoreactive. The immunoreactive cells were present in a group in the distal wall of the groove between forestomach and glandular stomach, as well as scattered singly in the surface and foveolar epithelia of the glandular stomach. Almost all immunoreactive brush cells had a thin basal process in contact with the basement membrane. No secretory granules with dense cores, similar to those of endocrine cells, were observed in the brush cells. The specific appearance of FABP-immunoreactivity in the brush cell indicates that this cell type is a distinct entity from other epithelial cells in the stomach and that FABP is a useful histochemical marker of the brush cells. FABP may be involved in the specific function(s) of this cell type related to fatty acid metabolism.     

The feeding habits of a group of herbivorous rock-dwelling cichlid fishes (Cichlidae: Perciformes) from Lake Malawi,Africa

Synopsis The feeding; habits of a group of tropical herbivorous rock-dwelling cichlid fishes from Lake Malawi, Africa, are investigated using stomach content analyses. The various species fed selectively on the periphyton of the rocky shores. Blue-green alga of the genus Calothrix was the most common item ingested by the group. Diatoms (Chrysophyta) also were abundant food items. Discriminant analysis showed that dietary items were good variables to identify species. Interspecific dietary differences showed a continuum from those species feeding primarily on Calothrix to those feeding primarily on diatoms. Algal resources exhibit distinct patterns of spatial variation. Diet was correlated with foraging behavior and trophic morphology. Interspecific differences in diet could possibly facilitate ecological coexistence among various species. Such coexistence would contribute to the maintenance of the high diversity fish faunas characteristic of the Great Rift Lakes of Africa.