CHANGES IN THE MAMMARY GLANDS OF RATS AND MICE DURING PREGNANCY, LACTATION AND INVOLUTION

Abstract

SUMMARY The relationships between indices of histological structure and levels of deoxyribonucleic acid (DNA) and lactose have been evaluated by estimating correlation coefficients from data for the rat and mouse, described in previous publications. Estimates are presented for correlations between the group totals, at different stages of the lactational cycle, and for correlations within these groups. Estimates for the latter type of correlation, obtained separately for each of the eleven groups, were examined for heterogeneity. The correlations obtained are discussed with reference to known causal relationships and with particular regard to differences in the magnitude of the relationships between stages and within stages. In these results the within-stage correlation between level of DNA and histological measures of cell number was low.