Figure 1

The effect of RARα1 /KO on neonatal and pubertal gland development. (a) Effect on the size of the neonatal glands. Number 4 glands were dissected from five to six days old wt and RARα1/KO C57Bl/6 or FVB, four mice per group, and whole mounts were prepared as described in Materials and methods. The area taken up by the mammary tree was analyzed using the Image J software. Bars are mean and SD of four glands per group. (b-e) Effect on pubertal mammary tree branching morphogenesis and terminal end buds. Number 4 mammary glands from seven to eight weeks old wt or RARα1/KO C57Bl/6 (b-d) and FVB pubertal mice (e) were dissected and processed for whole mounts and paraffin sections. Branching points were counted along the entire length of the three longest ducts. Bars show mean and SD of seven pairs (14 total) of number 4 glands per group (P = 0.0001, t-test). The same glands were used to count the peripheral terminal end buds (TEBs) (P = 0.00001, t-test).