Figure 5.
Alveolar development at day 1 of lactation in the absence of NFIB and STAT5. A, Whole mount of mammary tissue of Nfibf/fStat5f/f;WC dams shows attenuated alveologenesis. B, Heterogeneous alveolar development and incomplete filling of the fat pad is seen. The tissue consists of a mixture of mature, expanded (arrow), and small, underdeveloped (arrowhead) alveoli. C, Presence of pSTAT5 staining (red, arrowheads) in some alveoli next to alveoli that have lost STAT5 (asterisk) indicates mosaic expression of the Wap-Cre transgene. D, Cytoplasmic localization of WAP (red, arrowhead) and lack of WAP in the alveolar lumen (asterisk) suggest impaired secretion. E-cadherin is stained green, and nuclei are stained blue with 4′,6-diamidino-2-phenylindole. E and F, Hematoxylin and eosin–stained section of mammary tissue from Nfibf/fStat5f/f;WC dams at the onset of the second lactation shows the presence of expanded alveoli (arrow) interspersed with underdeveloped alveoli (arrowhead).