STRUCTURE AND BIOCHEMISTRY OF NORMAL AND MUTANT (HUB HUB) MOUSE MAMMARY TISSUE DURING GESTATION AND LACTATION/

Mammary gland structure and function in mutant hub/hub (hyper-unconjug ated bilirubinemia) mice were compared to controls (+/hub). Flips from normal and mutant mice have decreased weight gain when suckled by mut ant dams, Samples examined by light microscopy showed no apparent diff erences when excised at mid- (day 9-11) and late- (day 17-18) gestatio n, and early (day 3-4) lactation, There was some evidence that early i nvolution may be occurring in the hub mice at midlactation (day 10-11) . Total DNA was greater (33%) when sampled at midgestation in the norm al mice but lower (20%) at late gestation when compared to the hub mic e, Total protein concentration was higher (132%) during late gestation in hub mice but was lower (34%) by early lactation when compared to n ormal mice, Epidermal growth factor (EGF) in normal mice was 79% and 7 1% higher in early and midlactation, respectively, than in mutant mice , There were no differences in serum concentrations of progesterone be tween strains at any stage. From these results, there is a suggestion of premature production of proteins, possibly followed by early involu tion in hub mice. Milk yield was less in mutant mice than in normal mi ce. Low concentrations of EGF during lactation in mutant mice may part ially account for the decreased growth observed in mutant and normal p ups suckling mutant dams.