Local effects of EGF, α‐TGF, and EGF‐like growth factors on lobuloalveolar development of the mouse mammary gland in vivo

Abstract

Five-week-old female mice supplemented with estradiol and progesterone are able to respond to epidermal growth factor (EGF) and EGF-like growth factors (α-transforming growth factor [α-TGF] and crude mammary-derived growth factor) with local lobuloalveolar development when these growth factors are directly introduced into the mammary glands via slow-release cholesterol-based pellets. Contralateral glands receiving pellets containing only cholesterol showed no growth response. The local growth effect is maximal at 4–5 days of exposure to hormones and growth factors. The glands appear to be more sensitive to α-TGF than EGF, since local development is seen with one-fifth the level of the former vs. the latter growth factor and can be seen even in the absence of the systemic estrogen/progesterone supplement.