Involvement of androgen-induced growth factor (FGF-8) gene in mouse embryogenesis and morphogenesis

Androgen-induced growth factor (AIGF/FGF-8) has purified from a mouse mammary carcinoma cell line and its cDNA cloning revealed that AIGF is the eighth member of the fibroblast growth factor family. To clarify a biological role of FGF-8, Northern blot analysis of various adult tissues was carried out, but no expression was found. However, whole mount in situ hybridization of 7.5- to 14.5-day gestation (E7.5-14.5) embryos revealed six predominant expression domains: [1]primitive streak region (E7.5-9.75); [2]midbrain-hindbrain border (E8.0-10.5); [3]rostral forebrain (E8.0-10.5); [4]limb ectoderm and apical ectodermal ridge (E9.25-13.5); [5]nasal placode and epithelium (E9.5-12.5); and [6]branchial arch ectoderm (E8.5-11.5). The embryonic expression pattern suggests a unique role of FGF-8 in mouse development, especially in gastrulation, brain development, and limb and facial morphogenesis.