Search PubMed⌕ Search

Biomedical subjects

J Schowing

Publications and source records attributed to J Schowing.

12 recordsLinked to original sources
PubMed1992

Pathogenesis of diastematomyelia: can a surgical model in the chick embryo give some clues about the human malformation?

To reproduce diastematomyelia, a sagittal incision was carried out at the level of the rhomboidal sinus of 36- to 40-h-old chick embryos. A small piece of membrane shell, a small agar screen, or a piece of quail isochronous isotopic notochord was inserted into the gap. The embryos were killed and fixed after 9 days' incubation. Diastematomyelia was obtained in several embryos treated with interposition of a membrane screen or a piece of quail notochord. Microscopic examination revealed two hemicords, each containing its own central canal; in some cases one of the cords showed hydromyelia. Absence of the rump was seen in association with experimental diastematomyelia. The interposition of a resorbable agar screen did not succeed in reproducing diastematomyelia. The results of these surgical manipulations suggest that diastematomyelia cannot be explained by a primary disorder of neurulation. It supports the theory of noninvolution of a firm midline structure (probably the neurenteric canal, rapidly surrounded by mesodermal cells originating from the notochord), which prevents the fusion of the separated parts.

Animals↗
PubMed1990

Early development of the primitive cranial vault in the chick embryo.

The calcified tissues involved in the early morphogenesis of the cranial vault were studied by microradiographic analysis and histological techniques in 12 chick embryos on the 9th, 12th, and 14th days of incubation. On the 9th day, the frontal, parietal, and squamosal bones are comprised of a thin lamina of chondroid tissue deposited at a short distance from the fibers of the dura mater. Woven bone formation takes place in the calvarial mesenchyme only after the 12th day of incubation and occurs mainly on the external side of the chondroid primordium. The present data obviously indicate that the primitive desmocranium of the chick embryo, which is usually known to be formed by intramembranous ossification, consists first of chondroid tissue. This tissue represents thus the initial modality of skeletogenic differentiation within the cephalic mesenchyme of the cranial vault.

Animals↗
PubMed1990

Amoebicidal effect of essential oils in vitro.

The toxic effect of 84 essential oils was tested at different concentrations on Entamoeba histolytica. 15 of them were the most efficient. 5 of the latter were detailed to give the percentages of their components. Some families of plants have shown an homogeneity in the toxicity of their essential oils, while others, to the contrary, have presented heterogeneous amoebicidal activities. Further investigations should be made to identify amoebicidal effects of essential oils in vivo.

Amebicides↗
PubMed1989

Mouse neural crest cells secrete both urokinase-type and tissue-type plasminogen activators in vitro.

Neural tubes of E8-5 day mouse embryos were dissected and cultured in serum substitute-supplemented medium to allow the emigration of neural crest cells. After 48 h of culture the neural tubes were removed. The neural crest cells were then cultured for 12 h in serum-free medium, and their culture supernatant was studied by electrophoresis and zymography. The cultured cells were shown to secrete both urokinase-type and tissue-type plasminogen activators. When the truncal neural tube was divided in four equal segments, the secretion pattern of the two types of plasminogen activators was similar for the cells from the three most anterior segments; cells having migrated from the most caudal one, i.e. consisting of the neural plate, secreted a higher level of urokinase-type plasminogen activator. The secretion in vitro of plasminogen activators by neural crest cells is in accord with the postulated importance of these proteases in cellular migration.

Animals↗
PubMed1985

[Experimental production of anencephalic monsters by chick embryo microsurgery. Initial observations].

42 hour-old chick embryos are operated by microsurgical means. The encephalon, which is normally closed at this stage, is reopened and the incision extended to the level of 2nd or 3rd somites. The experimental embryos are anencephalic. Their comparison with a spontaneous anencephalus shows a large morphological similarity. These first experiments confirm the hypothesis by which anencephaly is a direct consequence of the failure of neural tube closure.

Anencephaly↗
PubMed1979

[A study of the early stages of biliary extrahepatic ducts organogenesis in the rat (Rattus norvegicus albinos) (author's transl)].

In the early stages of morphogenesis, the hepatic diverticulum of the rat develops as in other mammals. Its anterior part gives rise to epithelial cell-cords bound by an epithelial primary plate to a single hepatic duct which joins the liver to the midgut. The interlobular bile-ducts develop from secondary epithelial plates which derivate from the primary one. The posterior part of diverticulum gives rise to a duct which may be assimilated by its position, structure and evolution, to the initial cystic duct of other mammals. This duct never participates to the formation of biliary extrahepatic ducts, but builds the ventral pancreas. Cellular necrosis is observed in relation with the development of the anterior part of diverticulum during the three first days of the hepatic morphogenesis.

Animals↗
PubMed1977

[Influence of L.5-hydroxytryptophan (L.5-HTP) on the development of chick embryo].

L.5-hydroxytryptophan (L.5-HTP) injections provoke, in the chick embryo, some malformations of the nervous system, when treated at 24 hours of incubation. The same treatement after 48 hours of incubation does not lead to malformations, but to a reduction in size which is as much obvious as the embryos are treated at a later stage. It seems that there could be some relation between the serotonin metabolism and the growth hormon secretion.

5-Hydroxytryptophan↗
PubMed1976

[The effect of boric acid on the development of chick embryos treated at an early stage: preliminary results].

10 mul of a 2% boric acid solution are injected in chick embryos at 28 hours of incubation. The nervous system is always affected in its anterior and middle region, with exencephaly and reduction in size of the neural tube. Microphtalmy is frequent. The posterior limbs can be likewise altered, leading sometimes to symelia. The histological study shows furthermore that the notochord is locally hypertrophic or missing, at the same level where the nervous system is altered.

Animals↗
PubMedDate not supplied

Cranial morphogenesis.

The morphogenesis of the skull in the chick embryo is characterized by different steps, involving neural crest cell migration and appearance of chondroid tissue occupying the middle part of most of the ossification centres. This tissue represents the initial modality of the skeletogenic differentiation within the cephalic mesenchyme.

Animals↗