Duration of DNA Synthesis in Hyperplastic Alveolar Nodules of C3H/He Mouse Mammary Gland

Summary

Duration of DNA synthesis in the cells of the outgrowths of hyperplastic alveolar nodules (HAN) of C3H/He mouse mammary gland was studied by autoradiographic methods. The average duration of DNA synthesis in HAN outgrowth cells was estimated as 13.7 hours. Earlier it was shown that DNA synthesis in mouse mammary gland was influenced by the hormones, estradiol and progesterone, and the DNA replication time (8.2 hours) of the prelactating tissue after transplantation into virgin host changed to a value (21.5 hours) similar to that (20.7 hours) of the normal mammary cells of virgin mice. This indicates that the duration of DNA synthesis in mammary cells is adjustable to the endogenous hormonal environment of the host. The intermediate value (13.7 hours) of the duration of DNA synthesis in HAN outgrowth cells in virgin host was interpreted as due to an altered sensitivity of these cells to the host's hormonal control on DNA synthesis.