Showing papers on "Transdifferentiation published in 1983"
TL;DR: The comparison of RPE development in three species showed that the pattern and schedule of R PE growth and differentiation causally related to cell proliferation are significantly different, and cell proliferation is essential for RPE melanotic differentiation and for transdifferentiation into other cell types.
Abstract: Publisher Summary This chapter describes the proliferation and differentiation of retinal pigment epithelium (RPE) during development and regeneration. RPE is a pigmented monolayer of hexagonal cells of neural origin located between the neural retina and the choroid. It is one of the most important structures in the visual system because of the role it plays in the viability and function of the neural retina. The comparison of RPE development in three species (rats, chicks, and humans) showed that the pattern and schedule of RPE growth and differentiation causally related to cell proliferation are significantly different. The chapter discusses the proliferation of pigment epithelium cells in the amphibian retina and iris in the process of retinal and lens regeneration. The importance of analyzing the proliferative activity of pigmented epithelia of the amphibian eye is because of the amphibian's striking potential for the regeneration of the neural retina and lens. Cell proliferation is not only closely related to cell multiplication and the reduction of cell volume but is also essential for RPE melanotic differentiation and for transdifferentiation into other cell types.
159 citations
Journal Article•
97 citations
TL;DR: Recent work on transdifferentiation, mostly with chick embryos, was reviewed and efforts are under way to attempt to understand the mechanisms of trans Differentiation in relation to the transcriptional control of genes coding lens-specific proteins.
73 citations
TL;DR: It is suggested that NR cells become committed or 'transdetermined' into lens direction before detectable expression of the lens phenotype, when cultured in SpC for 10 days, rather than under conditions of stationary culture, as previously suggested.
22 citations
TL;DR: It is concluded that large scale alterations in the pattern of DNA methylation are not a necessary accompaniment to changes in gene activity and that dramatic changes in delta-crystallin gene expression occur during transdifferentiation.
11 citations
TL;DR: The influence of lens epithelium of adult frogs on the character of transdifferentiation of retinal pigmented epithelia of adultfrogs and tadpoles of Rana temporaria has been studied and the problem of the relative significance of inducing determinants and the role of activation or inhibition of proliferation in trans Differentiation is discussed.
10 citations
TL;DR: A difference in the expression of lens phenotypes resulting from the different ratios of H- and L-fraction was confirmed by monitoring the level of delta-crystallin in cultures.
Abstract: By centrifugation in a Percoll gradient, two cell fractions were separated from cell populations harvested from 8-day cultures of neural retina cells of 3·5-day-old quail embryos. The heavy (H-) fraction contained mostly N-cells, which are considered to be putative neuronal cells, while the light (L-) fraction contained both E-cells, putative retinal glial cells, and Ncells. Determination of choline acetyltransferase activity in both fractions suggested that this enzyme is predominantly localised in N-cells. After replating the separated L-fraction for further culturing, frequent lentoidogenesis occurred from clusters of N-cells which, though few in number, were included in this fraction. Addition of H-fraction to L-fraction cells caused a significant increase in lentoidogenesis up to a ratio of N- to E-cells of 3:1. However, addition of excess H-fraction cells beyond this ratio inhibited lens differentiation. This difference in the expression of lens phenotypes resulting from the different ratios of H- and L-fraction was confirmed by monitoring the level of δ-crystallin in cultures. These results are discussed in the light of interactive relationships between N- and E-cells in the transdifferentiation of neural cells into lens in cell culture
8 citations
TL;DR: It is suggested that a study of the physiological basis of light-induced destruction and transdifferentiation of neural retina in culture could play an important role in the development of therapeutic measures for the control of retinal degeneration in man.
6 citations
01 Sep 1983
TL;DR: It was suggested that cells in the N2-fraction are primitive neuroblast-like cells, and it can be concluded that putative neuronal cells in early cultures of avian embryonic neural retina can transdifferentiate into lens cells.
Abstract: To elucidate the cell-type origin of lens cells, which differentiate in stationary cultures of neural retina, chimeric cultures between chick and quail cells were made to recombine xenoplastically the different cell fractions separated from 8- to 9-day cultures of 3.5-day-old embryonic neural retinal cells by means of centrifugation in Percoll. Extensive lentoidogenesis occurred in the recombination of the N2-fraction (consisting mostly of small round cells) with the E-fraction (containing a number of flattened epithelial cells). Taking advantage of the difference in electrophoretic mobility of chick and quail δ-crystallin, it was shown that this lens-specific protein, synthesized in the chimeric cultures, was mostly of the species-specificity of N2. Microscopic observations of histological sections of cell sheets of quail N2- and chick E-fraction chimeric cultures revealed that most cells with δ-crystallin, as identified by means of immunohistological detection, are provided with a nuclear marker characteristic of quail. By determining the level of activity of choline acetyltransferase and by examining the stainability with a fluorescent dye (Merocyanine-540), it was suggested that cells in the N2-fraction are primitive neuroblast-like cells. Thus, we can conclude that putative neuronal cells in early cultures of avian embryonic neural retina can transdifferentiate into lens cells.
5 citations