Monolayer cultures of normal, preneoplastic and neoplastic murine mammary epithelial cells were exposed to various types of mammalian serum. A progressive decline in levels of thymidine incorporation together with a change in the ordering of sera which stimulates optimal incorporation was observed in the transformed cells.

Animals↗

PubMed1977

The effects of various mammalian sera on attachment efficiency and thymidine incorporation in primary cultures of mouse mammary epithelial cells.

Mammary epithelial cells from 16- to 17-day pregnant BALB/c mice were cultured in various mammalian sera to determine the kind of serum which stimulates optimal attachment efficiency and thymidine incorporation. Of those sera tested, horse, bovine, lamb, goat and fetal bovine provided the highest attachment efficiency, whereas rat, mouse and human gave the lowest. Rabbit serum stimulated the highest thymidine incorporation into TCA-insoluble material with goat and rat providing the lowest. These results suggest that sera which provide the highest attachment efficiency for primary cultures are not the best stimulants of DNA synthesis and show that an inverse relationship exists between cell attachment and thymidine incorporation for any given type of mammalian serum.

Animals↗

PubMed1975

An immunologically distinct milk protein in mouse whey.

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Animals↗

PubMed1975

Localization of casein-rich, fat-rich and DNA-synthesizing cells in monolayer cultures of mid-pregnant mouse mammary epithelium.

Monolayers of 16-day pregnant BALB/cfC3H/Crl mouse mammary epithelial cells were examined for the occurrence and distribution of cells which contain large amounts of casein and fat and those which synthesize DNA. Cells within the central portions of epithelial cells appeared rich in casein and fat, whereas cells on the peripheral edges of the colonies synthesized DNA almost exclusively. Casein deposits and DNA synthesis were mutually exclusive phenomena, since only 2% of the cells synthesizing DNA also stained for casein. Of the casein-rich cells, 74% were also rich in fat, suggesting that cells wich contain large deposits of casein almost always contain large amounts of fat. These results indicate that a specialization of function exists between cells on the growing edge and those centrally located within a single colony of mammary epithelial cells.

Animals↗

PubMed1974