A histological and biochemical study of hormone-dependent differentiation of mammary gland tissue in vitro

Induction of erythroid differentiation by dimethylsulfoxide in cells infected with Friend virus: relationship to the cell cycle.

“…DNA synthesis and cell proliferation may be required for differentiation in a number of cell systems (5)(6)(7)(8)(9)(10)(11)(12)(13)(14). Examples of a relationship between DNA synthesis and initiation of synthesis of proteins characteristic of the differentiated state come from studies on mammary tissue (6), and on uterus and oviduct (7), melanoma (8), erythropoietic (9)(10)(11)(12), muscle (12,13), myeloma (14), and lymphoid cells (15), as well as sporulation in Bacillus subtilis (16). These investigations, however, have not provided evidence whether the differentiative transition occurred during a specific phase of a particular cell cycle.…”

Effect of Various Concentrations of Prolactin and Growth Hormone on the Magnitude of Stimulation of RNA Synthesis, Casein Synthesis and Ornithine Decarboxylase Activity in Mouse Mammary Gland Explants

“…These results are in contrast to those of Turkington [ 17] using cultured mouse tissues and Hallowes et al [ 18] using cultured rat tissues; these authors observed maximal rates of [32P] incorporation into casein with prolactin concentrations as high as 0.5-5 pg/ml. Since the experiments of Stockdale et al [16], Turkingion [17] and Hallowes et al [18] were all carried out with (a) prolactin present in the culture medium for 48 h and (b) prolactin present from the time of preparation of the explants, it seems possible that hormone degradation during culture may explain why these authors had to use such high concentrations of prolactin to obtain maximal effects on casein synthesis.…”

“…These authors observed maximal responses to prolactin with a con centration of about 20 ng/ml; this correlates quite well with our experimen tal results. Several years ago, Stockdale et al [16] also observed a limited concentration-response curve for prolactin action on [32P] incorporation into casein. They observed no response at 10~9 M prolactin (about 20 ng/ml), but a maximal response at the next highest concentration tested, 10-8 M (about 200 ng/ml).…”

Growth factors in mammary gland function

“…This would explain the supraphysiological concentrations of insulin (~10~6m) which are generally found to be necessary to stimulate cell replication in mammary expiants (Stockdale et al, 1966;Skarda et al, 1977) and to potentiate maximally the effects of prolactin on lactogenesis in vitro (Houdebine et al, 1985). It would also explain why diabetic animals show no significant impairment of mammary growth (Norgren, 1968;Topper & Freeman, 1980).…”