Abstract
Summary
1) Using DNA as index of mammary gland growth, a study of changes from virgin throughout pregnancy and lactation in Webster-Swiss mice was conducted. Previous morphological studies were interpreted as indicating complete lobule-alveolar development by the first 1/2-2/3 of pregnancy. Our data show however, only 30.6% of total growth during first 12 days of pregnancy, 45.7% in latter half of pregnancy and 21.9% further proliferation from parturition to day 14 of lactation. 2) Growth of the gland continues throughout pregnancy, but in pseudo-pregnancy it is completed by day 6. 3) DNA level of ovariectomized lactating mice is similar to normal lactators, indicating corpora lutea of lactation does not contribute to additional growth of mammary gland.
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