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S R Hilfer

Publications and source records attributed to S R Hilfer.

48 records · Page 3Linked to original sources
PubMed1971

The expression of differentiation by chick embryo thyroid in cell culture. II. Modification of phenotype in monolayer culture by different media.

Previous results with thyroid secretory cells in monolayer culture seem contradictory with respect to phenotypic stability of this cell type. On the one hand, in "minimal" medium the cells lose structural and functional specializations which can be returned only by three-dimensional growth in organ culture upon addition of fibroblasts derived from the thyroid capsule. On the other hand, in "rich" medium used for cloning, cytoarchitecture and function remain unaltered in either mass or clonal cultures. The apparent discrepancy has been resolved by plating cell suspensions in both media and changing to the alternate medium once the cells have become established. It has been shown that a number of characteristics, including hormone levels, are reversed each time such a change in medium is made. These modulations are discussed in terms of the normal variations in structure and function of the gland in vivo.

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PubMedDate not supplied

Effects of hormones on functional differentiation of mouse respiratory epithelium.

The effects of corticosteroids and thyroxine on morphogenesis and differentiation of fetal respiratory epithelium were tested in serum-free culture. Strips from the margins of 16-day fetal mouse lungs, containing future respiratory branches, were cultured in medium containing growth factors plus different concentrations of dexamethasone and/or thyroxine. After 5 days, some of the cultures were processed for electron microscopy and the rest were used to quantitate unsaturated and saturated phosphatidylcholine. In the absence of thyroxine and dexamethasone, the lung tissue developed the equivalent of one more day in utero during the 5 days of culture, perhaps because of residual hormone in the tissue. Thyroxine and dexamethasone in concentrations compatible with normal physiological conditions permitted normal development from the pseudoglandular stage to the saccular stage, differentiation of respiratory cell types, and normal surfactant accumulation. Thyroxine alone gave essentially the same lack of morphological maturation and accumulation of disaturated phosphatidylcholine as culture in the absence of all hormone, but columnar epithelial cells held increased numbers of lamellar bodies. Dexamethasone alone at 10(-6) M gave essentially normal development. Dexamethasone at 10(-9) M was sufficient to permit almost normal development when combined with 10(-7) M thyroxine. We conclude that dexamethasone is required for normal maturation of the fetal lung and that thyroxine acts synergistically to lower the dexamethasone requirement. The presence of apparently authentic lamellar bodies under some conditions of low disaturated phosphatidylcholine accumulation make this morphological criterion suspect as a test for differentiation of type II cells.

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