Can dietary fat influence hormone-induced growth responsiveness of the mammary gland?

Hormone-induced mammary gland growth responsiveness was examined in female Balb/c mice fed three different dietary levels (0, 5, and 20%) of fat (corn oil). Increasing the quantity of dietary fat enhanced hormone-induced mammary gland developmental growth processes both in vivo and in vitro. The effect of dietary fat was quite striking when comparing mice fed 0 and 5% fat diets and was less pronounced but still present when comparing mice fed 5 and 20% fat diets.