Showing papers on "Transdifferentiation published in 1978"

'Transdifferentiation' of chicken neural retina into lens and pigment epithelium in culture: controlling influences.

Abstract: The in vitro transdifferentiation of chicken embryo neural retina into pigment epithelium and lens cells was investigated under a variety of experimental conditions. Our findings suggest that some aspects of the phenomena are a function of medium composition and volume, whereas others depend upon conditions which develop during culture growth. Before melanin is visible, potential pigment cells are recognized as foci within epithelial sheets which remain in contact with the dish. The final area occupied by colonies of potential pigment cells is directly proportional to bicarbonate concentration. Low total medium volume also favours formation of potential pigment cells. In contrast the extent of cells other than potential pigment cells is not related to bicarbonate and is favoured when the volume of medium is large. Accumulation of melanin within the potential pigment cell colonies is suppressed when cells are crowded together. Lentoid bodies are formed from cells which are distinct from potential pigment cells and arise in crowded situations, in association with multilayering. Another type of structure superficially resembling a lentoid is derived from cell aggregates formed during the initial establishment of cultures. The survival of these 'aggregate bodies' is inversely related to bicarbonate concentration. Crystallin content is unrelated to lentoid numbers. The results provide the basis for a new hypothesis concerning cytodifferentiation in this system.

Influence of embryonic stage on the transdifferentiation of chick neural retina cells in culture

Abstract: Neural retina cells from chick embryos up to 15 days of incubation can transdifferentiate in culture into both lentoids and pigment cells. Some transdifferentiation into pigment cells but none into lentoids was found in cultures of 17-day embryonic neural retina. No transdifferentiation occurred in cultures of neural retina from embryos immediately before hatching. In general, lentoids and pigment cells develop more rapidly and in greater numbers in cultures of neural retina from the earlier embryonic stages, and lens-specific crystallins also appear earlier and accumulate in greater amounts in these cultures. Delta crystallin accumulation is much greater in transdifferentiating cultures of early embryonic neural retina, wheras alpha and beta crystallins become proportionately more prominent in cultures of late embryonic neural retina. Traces of alpha and beta but not delta crystallin are detectable in 60-day cultures of 17-day embryonic neural retina. Analogies between these results and the ontogeny of crystallin polypeptides in lens cells in vivo are discussed.

Developmental approaches to organ restoration.

Abstract: This paper discusses the problem of applying the achievements of developmental biology to organ restoration. Experiments on artificially induced transdifferentiation as a prerequisite for organ restoration are reviewed. The advantage of using cells that start differentiation from the dedifferentated state is that they can participate in the construction of new organs. However, cell transdifferentiation is not sufficient for biomedical purposes, since the problem of construction of typically formed organs--namely, the morphogenesis of groups of differentiating cells--remains to be solved. Data, where a partial approach to typical organ restoration has been achieved are analysed. This serves as a tentative step in the application of developmental-biological approaches to the problem of organ restoration.