Figure 2.

Hypoplasia is evident in the mammary glands of the Aabbdd, aaBbdd, and aabbdd mutant females during pregnancy and around parturition. A and B are whole-mount preparations (×2.5). C, D, G, and H are sections under low magnification (×62). E, F, I, and J are sections under high magnification (×250). A, C, and E are from the fourth mammary glands of wild-type females at 12.5 days of pregnancy. B, D, and F are from the fourth mammary glands of aabbdd females at 12.5 days of pregnancy . G and I are from the fourth mammary gland of a wild-type female shortly post partum. H and J are from the fourth mammary gland of an aabbdd female shortly post partum. The mammary epithelia (e) include mammary ducts (d) and lobuloalveolar structures (a) in pregnant and lactating females. The mammary stroma (s) consist mainly of fat cells (f) and fibroblasts. The arrow in J points to an intracellular oil droplet in an alveolar cell.