Nucleic Acids of the Mammary Glands of Rats.

Abstract

Desoxypentose (DNA), pentose (PNA) nucleic acids, and N were studied in the mammary glands of virgin, pregnant, lactating and post-lactating rats. The DNA per total gland (gland plus fatty pad) increased to mid-pregnancy and then increased only slightly through lactation. PNA increased in the 1st half of pregnancy parallel to DNA but continued to increase throughout lactation, reaching a max. value at 21-22 days of lactation. The N content of the gland (uncorrected for milk) paralleled PNA content. At involution of the gland the values of DNA, PNA and N fell rapidly. The DNA values indicate that the major portion of mammary growth (cell proliferation) is reached at mid-pregnancy. PNA increases simultaneously with the total synthetic ability of the gland. PNA increases above DNA (expressed by PNA-DNA ratio) indicating hypertrophy in mammary epithelium when it is in secretory condition.