Cells from early chick embryos in culture.
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Animals↗
Biomedical subjects
E Mitrani
Publications and source records attributed to E Mitrani.
Hypoblastic cells can form a disk inducing an embryonic axis in chick epiblast.
The primitive streak of the chick embryo develops from one of the two layers of cells of the stage XIII blastoderm, the epiblast. The other layer of cells, the hypoblast, seems to be necessary for the induction of the primitive streak and also determines its orientation--rotation of the hypoblast by 90 degrees is followed by a similar rotation of the embryonic axis. After stage XIII, the hypoblast is replaced by the invaginating endoderm and plays no further part in the development of the embryo. By means of a technique for disaggregation and reconstituting cells of stage XIII hypoblasts, we have been able to show that the two functions, induction and orientation are independent and that with reconstituted hypoblasts, the orientation of the primitive streak is determined by the epiblast.
Animals↗
A computer model for epidermal cellular interactions.
A model has been constructed of an assembly of mammalian epidermal cells. The model, simulated by computer, has served as a framework by which experiments can be performed "in machina". Relationships between the various parameters considered have been established. Hypotheses referring to the time at which cells leave the basal layer, and to the simultaneous occurrence of folded basal layer and of a significant number of vertical mitosis in some hyperplastic conditions have been implemented and examined.
Animals↗
Procollagen synthesized by newborn rat skin in culture.
Newborn rat skin explants in culture have been found to synthesize and secrete into the medium a considerable amount of collagen precursors (procollagens). Gel-electrophoresis analysis of the material extracted from the medium indicates that it is constituted mainly by procollagen Type I with a small percentage of procollagen Type III. Antibodies have been raised to the extracted procollagen and, although no attempt has been made to render these antibodies specific to one procollagen type by appropriate immunoadsorption, the immunofluorescence patterns that have been obtained are in good agreement with those reported on procollagen Type I by other groups. When unfixed cultured fibroblasts are examined by indirect immunofluorescence in the presence of the antiprocollagen antibody, a fluorescent network of interwoven fibres on the cell surface is observed which is similar to the network formed by fibronectin (LETS) on the fibroblasts' cell membranes.
Animals↗
Possible role of connective tissue in epidermal neoplasia.
Interactions between epidermal cells have been defined within a proposed mathematical model of mammalian skin. Testing the model in a computer suggests that in highly proliferating conditions of the epidermis competition for cell space in the basal layer may be sufficient to generate considerable forces in the papillary dermis. Data shown from human and pig epidermal hyperplasia indicate that basal cells are submitted to considerable lateral forces and that these and not dermal hyperplasia are the forces responsible for the increasingly folded dermo-epidermal junction. When the model was examined in condition of persistently high mitotic rate it was found that it could remain stable only if new connective tissue synthesis was not induced by the developing papillary tension. This complex and counterproductive relationship that may occur between epidermis and dermis and its possible role in the development of neoplasia are discussed.
Animals↗
Towards characterization of epidermal cell migration promotion activity in serum.
The effect of various fractions of serum on active epidermal cell migration in vitro has been studied by incubating small explants of normal human skin in the presence of the fractions and determining the extent of migration after 48 h incubation. Serum was fractionated by combining ammonium sulphate precipitation and molecular sieve chromatography using Sephadex G-200. The components of serum responsible for most, if not all, of the migration promotion activity were localized in the G-200 third peak (albumin fraction) of the supernatant after precipitation of the serum with ammonium sulphate at 50% saturation.
Blood Physiological Phenomena↗