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N Skreb

Publications and source records attributed to N Skreb.

13 recordsLinked to original sources
PubMed1991

Retinoic acid can change normal differentiation of rat egg-cylinders cultured in vitro.

The modified organ culture of rat egg cylinders provides favorable conditions for 2 weeks for the differentiation of main tissue types. To study the effect of retinoids on early rodent differentiation, retinoic acid (RA) was added in various concentrations to serum-supplemented or serum-free medium. Explant survival decreased when RA was added to serum-free medium. Although the cartilage was well differentiated even in cultures deprived of serum, RA inhibited chondrogenesis in all cultures without or with serum. The frequency of columnar epithelium was higher and its folds more often present when RA was added to the medium. Keratinization of squamous epithelium depended on the RA concentration added to the medium, and was almost absent when the concentration was high. Other tissues often present in serum-supplemented medium (such as neuroblasts and myotubes) were not affected by RA, a result that differs from those obtained in other experimental systems.

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PubMed1991

Neural growth factor inhibits the growth of rat egg-cylinders cultured in vitro.

Rat egg-cylinders at the primitive streak stage were grown in modified organ culture for 2 weeks using a chemically defined medium. Differentiation of the epidermis and cartilage was comparable to that in fully serum-supplemented medium, whereas neuroblasts were very scarce. In explants treated either with bovine serum albumin or transferrin, neuroblasts were observed, whereas the addition of NGF did not improve neuroblast differentiation. On the contrary, NGF impaired growth and tissue differentiation when compared with explants grown in serum-free medium.

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PubMed1990

Transferrin enhances lentoid differentiation in rat egg cylinders cultivated in a chemically defined medium.

Rat egg cylinders at the primitive streak stage were grown in modified organ culture for 2 weeks using a chemically-defined medium. The purpose of the experiment was to determine whether the terminal tissue differentiation is modified by human transferrin. The control sets were grown in medium with or without rat serum. In explants treated with transferrin, groups of atypical cells of the ocular lens (lentoids) appeared more frequently than in both control sets; however neuroblasts were observed as often as in the serum-supplemented medium. Bovine serum albumin (BSA) stimulated the differentiation of neuroblasts but did not promote lentoid formation. We conclude that human transferrin does stimulate the differentiation of lentoids in rat embryonic explants, but the mechanism of its action remains unknown.

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PubMed1987

Partial differentiation of rat egg cylinders in serum-free and protein-free medium.

Modified organ cultures of rat egg cylinders were grown for 2 weeks in Eagle's MEM without serum or with serum added at different times. Explant survival was decreased only in cultures grown for the entire 2 weeks in serum-free medium, whereas the explant growth was impeded in all but the cultures grown for 2 weeks in 50% MEM plus 50% serum. Differentiation of epidermis and cartilage in the cultures deprived of serum for the entire 2-week period was comparable to that in fully serum-supplemented medium, whereas other differentiated tissues were rare or absent. In explants cultivated without serum for only the first week, neuroblasts were scarce.

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PubMed1979

Teratomas.

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Animals↗
PubMed1977

Effect of dibutyryl cAMP and theophylline on cultured rat embryonic shields.

Effects of N6, O2 dibutyryl adenosine 3',5'-cyclic monophosphate (db-cAMP) and theophylline (Th) on cultured rat embryonic shields were studied. After addition of db-cAMP to the culture medium, an increase of the weight of explants and of the incidence of the skeletal muscle was observed. Theophylline seems to be ineffective.

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PubMed1977

Origin of embryo-derived yolk sac carcinomas.

The origin of yolk sac carcinoma obtained from rat embryos transplanted to extrauterine sites was traced to the extraembryonic portion of 9-day egg-cylinders. Under appropriate conditions cells of the extraembryonic portion of the egg cylinder differentiate into cells of parietal yolk sac epithelium, continue to proliferate and form retransplantable malignant tumors. Serum concentrations of alpha-fetoprotein were elevated in rats bearing yolk sac carcinomas and in some animals bearing teratomas admixed with yolk sac carcinoma. Possible factors that regulate the survival and proliferation of yolk sac epithelium in extrauterine sites are briefly discussed.

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