Lymphocytes,but not cancer cells are able to penetrate into the rat embryo yolk sac wall

Summary Normal rat lymphocytes and cells of 2 highly invasive tumors, the L5222 rat leukemia and the V2 rabbit carcinoma, were inoculated in vitro on the mesothelial surface of the visceral wall of the rat embryo yolk sac. After 48 h, lymphocytes, without any damage being inflicted on the mesothelial cells, had penetrated deeply into the yolk sac wall, whereas both kinds of cancer cells had destroyed the mesothelial cells, but not advanced beyond the basal lamina.     

Biosynthesis of ascorbic acid in chick embryos

Biosynthesis of ascorbic acid was found in the kidneys (mesonephros and metanephros) of the chick embryo as well as in the yolk sac membrane. The activity of L-gulonolactone oxidase in the yolk sac membrane suggested that it was the major source of ascorbic acid in the chick embryo.     

Deconvoluting the ontogeny of hematopoietic stem cells

Two different models describe the development of definitive hematopoiesis and hematopoietic stem cells (HSCs). In one of these, the visceral yolk sac serves as a starting point of relatively lengthy developmental process culminating in the fetal liver hematopoiesis. In another, the origin of adult hematopoiesis is split between the yolk sac and the dorsal aorta, which has a peculiar capacity to generate definitive HSCs. Despite a large amount of experimental data consistent with the latter view, it becomes increasingly unsustainable in the light of recent cell tracing studies. Moreover, analysis of the published studies supporting the aorta-centered version uncovers significant caveats in standard experimental approach and argumentation. As a result, the theory cannot offer feasible cellular mechanisms of the HSC emergence. This review summarizes key efforts to discern the developmental pathway of the adult-type HSCs and attempts to put forward a hypothesis on the inflammatory mechanisms of hematopoietic ontogenesis.     

Biosynthesis of ascorbic acid in chick embryos

Summary Biosynthesis of ascorbic acid was found in the kidneys (mesonephros and metanephros) of the chick embryo as well as in the yolk sac membrane. The activity of L-gulonolactone oxidase in the yolk sac membrane suggested that it was the major source of ascorbic acid in the chick embryo.I am grateful to Dr R. Jenness (Univ. of Minnesota) for the generous gift of L-gulonolactone and to Dr B. Sanders (Univ. of Texas) for the chick embryo samples     

Pseudolymphoma of skin induced by oriental hornet (Vespa orientalis) venom.

Intradermal injection of saline suspension of Vespa orientalis venom sac to 57 black mice caused a local nodule composed of lymphocytes, few histiocytes and plasma cells 10 to 12 days following the injection. This reaction simulates the pseudolymphoma reaction observed in humans following arthropode stings.     

A possibility to achieve genetic transformation in the platyfish-swordtail system (Platypoecilus maculatus — Xiphophorus helleri)

Summary In order to determine how informative homologous donor DNA might be made available to propigment cells of the recipientXiphophorus helleri for transformation, labelled heterologous DNA fromE. coli was injected into the neural crest region or the yolk sac of embryos of the recipient. On the basis of the degradation rate of the donor DNA and the incorporation rate of radioactivity into the recipient DNA, it is concluded that injection into the neural crest region may be a suitable method to make available informative homologous donor DNA for transformation.Supported by DFG through SFB No. 103, and by Stiftung Volkswagenwerk.     

Effect of different methods of exposure to cyproterone acetate on mortality in chick embryos

Summary 33-h chick embryos exposed to 0.25 mg or 0.50 mg cyproterone acetate injected into the yolk sac showed a significantly lower mortality rate than embryos receiving the same dosage applied directly onto the developing blastodisc.This work was supported by a Government Research Support Grant awarded to Louisiana State University School of Medicine. Cyproterone acetate supplied through courtesy of Schering AG, Berlin, West Germany.     

Etude cytofluorométrique et histoautoradiographique de la synthèse d'ADN et de protéines sur des cellules mésothéliales humaines

Summary The study of nuclear DNA synthesis of human mesothelial cells showed that cells do not divide by mitosis, even if an important percentage of them have a tetraploid amount of DNA. Concerning the cell cycle of mesothelial cells, the authors conclude that some of them are blocked in postsynthesis.     

Existence of cholinergic receptors in the very young chick embryo]

The injection of certain cholinergic agents in the yolk sac of young Chick embryos (40 to 48 hrs. of incubation) gives rise to a twisting of the cervical notochord and spinal cord and contraction of the cervical somites. These morphogenetic changes result in spinal column malformations in older embryos. The effects of the cholinergic agents are inhibited by simultaneous treatments with a cholinergic agonist and an antagonist or a cholinergic receptor ligand. The results lead to the assumption that the early embryos already possess cholinergic receptors, probably located in the notochord.     

Differences in utilization of tritiated thymidine and tritiated deoxycytidine by rat lymph node cells.

Large lymphoid cells and plasma cells in antigenically stimulated rat lymph nodes retain less label after injection of 3H-CdR than after injection of 3H-TdR. There is no difference amongst small lymphocytes. The data are consistent with a defect in the utilization of 3H-CdR in the late stages of B cell maturation in the rat.     

Epitheliophagy: intrauterine cell nourishment in the viviparous alpine salamander, Salamandra atra (Laur.)

The intrauterine nourishment of the viviparous alpine salamander, Salamandra atra, has been demonstrated to consist of two phases: oophagy - after hatching from the jelly membrane, the developing embryo ingests the remaining disintegrated, unfertilized egg mass. Epitheliophagy - a special cranial portion of the uterus wall, the zona trophica, is stimulated by the presence of the embryo. After the yolk mass has been exhausted, the developing embryo is supplied with epithelial cells as nourishment until the end of pregnancy. The epithelial cells of the zona trophica are released into the uterus lumen by partial necrosis of the underlying connective tissue. Regeneration and detachment of the uterine epithelium occur simultaneously in different regions of the zona trophica. A special dentition enables the embryo, according to its position in the uterus, to feed directly on the zona trophica.     

Differences in utilization of tritiated thymidine and tritiated deoxycytidine by rat lymph node cells

Summary Large lymphoid cells and plasma cells in antigenically stimulated rat lymph nodes retain less label after injection of³H-CdR than after injection of³H-TdR. There is no difference amongst small lymphocytes. The data are consistent with a defect in the utilization of³H-CdR in the late stages of B cell maturation in the rat.     

Mesothelzellveränderungen nach der intraperitonealen Injektion von denaturiertem Phytohaemagglutinin

Summary After the i.p. injection of heat denatured PHA, mesothelial cell changes are similar to those found after the application of natural PHA. While vacuolization of mesothelial cells and signet ring cell formation is strongly marked after the injection of natural PHA, this reaction is minor if denatured PHA is used. Furthermore, the peritoneal fluid does not contain hyaluronic acid in detectable amounts.

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Die Untersuchungen wurden mit finanzieller Unterstützung durch die Deutsche Forschungsgemeinschaft durchgeführt.     

Morphofunctional changes in the mitochondrial subpopulations of conceptus tissues during the placentation process

To establish the role of mitochondrial subpopulations in the mitochondrial maturation process, we studied morphological and functional changes in the mitochondria of different mammalian conceptus tissues during the organogenic and the placentation processes. Mitochondrial subpopulations of three different conceptus tissues, embryo and visceral yolk sac placenta on gestational days 11, 12 and 13 and placenta on days 12 and 13, were examined morphologically by transmission electron microscopy. Cytochrome oxidase activity and protein levels were also measured in each mitochondrial subpopulation. The results indicate two different mitochondrial subpopulation profiles: a homogeneous one, which corresponds to immature mitochondria, and a heterogeneous one, which represents the mature mitochondria. The three tissues studied show different morphologic and metabolic patterns of mitochondrial maturation during the placentation process, rendering them suitable as experimental models to establish the p ossible relationship between mitochondrial maturation and the mitochondrial subpopulations. Received 5 August 2002; received after revision 23 September 2002; accepted 8 October 2002 RID="*" ID="*"Corresponding author.     

The effects of triaminopyrimidine on the short circuit current and transmembrane potentials of the isolated rat visceral yolk sac in vitro

Summary Intracellular potentials in the cells from 17.5-day old rat visceral yolk sacs were measured by a glass microelectrode. When penetrated from the maternal side, the cells have potentials of about 50.2±1.9 mV (inside negative) which were reduced by increasing the external K⁺ concentration and increased by removing Na⁺ ions from the bathing fluid. Triaminopyrimidine (TAP) which inhibited Na⁺ transport caused a dose-dependent depolarization of the cell membrane. The depolarization was dependent on the presence of extracellular Ca²⁺ ions. It is proposed that TAP may inhibit Na⁺ transport by increasing the intracellular concentration of calcium ions.This work was supported by the University of Hong Kong (grant number 335. 034.5105).Acknowledgment. Triaminopyrimidine was synthesized by Dr. Barbara Roth of the Wellcome Research Laboratories.     

Length-tension dependence in vascular smooth muscle: Possible participation of endothelin

The results of experiments with isolated strips of rat portal vein, and of ‘sandwich’ experiments involving strips of the portal vein or aorta, revealed the involvement of endothelin in the development of myogenic reactions of the vascular smooth muscle, observed on distension of the vascular wall. Released by the endothelial cells, endothelin is capable of stimulating the contraction of these muscles.     

Antigenic correlation between rat brain synaptic vesicles and rat bone marrow B lymphocytes.

Rabbit anti-rat brain synaptic vesicle serum reacted with thymocytes and B lymphocytes in cytotoxicity and immunofluorescence assays. Quantitative absorption analysis revealed that this antiserum contained antibodies specific for antigenic determinants on the surface membrane of a subpopulation of rat bone marrow B lymphocytes.     

Methods of experimental yolk removal fromBrachydanio rerio eggs

Summary The yolk ofBrachydanio rerio eggs was removed by pipettation, bursting and cutting off with a scalpel. The total yolk removal before the 8-cell stage led to a germ with irregular groups of cells, at the 8-cell stage to a topologically irregular differentiation, at the 64-cell stage to a nearly normal embryo, which is not viable.     

Die Transformation von Mesothelzellen in Hyaluronsäure produzierende Siegelringzellen

Summary After injection of PHA into the peritoneal cavity of rats, parietal mesothelial cells were transformed into hyaluronic-acid-producing signet-ring-cells.

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Die Untersuchungen wurden mit Unterstützung der Deutschen Forschungsgemeinschaft durchgeführt.