Angiogenic activity of anterior pituitary tissue and growth hormone on the chick embryo chorio-allantoic membrane: a novel action of GH.

A useful system to evaluate the angiogenic activity of hormones and growth factors is the chorioallantoic membrane (CAM) of chick embryos. The present studies examined the angiogenic activity of chicken anterior pituitary glands and both fibroblast growth factor (FGF) and growth hormone (GH). Grafts of anterior pituitary gland evoked an angiogenic response on the CAM which was lost if the adenohypophyseal tissue was first boiled. The magnitude of the angiogenic response to anterior pituitary glands increased with the age of the donor (from a minimum 15 days of embryonic development to a maximum between 2 and 6 weeks old). In view of the similarity of the profile of the angiogenic response and the reported changes in GH secretion, the angiogenic activity of GH was then examined. Considerable angiogenic responses were observed with GH; there being increases (P < 0.05) in number of new blood vessels on the CAM of chick embryos on which native chicken GH or native bovine GH or recombinant bovine GH were added. These data support GH having an angiogenic action.