General Mg

Question 1

What factors are required for TEB formation?

Answer 1

Estrogen, FGF10, and GH are required for TEB formation.

Wnt, SLIT, and TGFβ have subtle, sometimes divergent roles in TEB morphology and function.

Question 2

Describe the role of estrogen signaling in ductal outgrowth.

Answer 2

Estrogen is required for TEB formation. It primarily comes from the ovaries, but can also be synthesized locally in the MG by adipose tissue and aromatase.

Estrogen is required for sustained proliferation during ductal elongation and acts directly on the epithelium via ERα.

Question 3

Describe the role of progesterone in mammary gland formation.

Answer 3

Progesterone receptor (PR) signaling in the stroma is important for ductal outgrowth but not alveolar budding.

Epithelial PR signaling is dispensable for ductal outgrowth but required for alveolar budding.

Question 4

Describe the role of growth hormone (GH) in mammary gland formation.

Answer 4

GH is produced by the pituitary but can also be produced in the ovary.

GH promotes TEB formation via paracrine IGF-1 signaling in the stroma. IGF-1 is required for TEB formation.