Functional EGF receptors are present on mouse embryo tissues

Abstract

Epidermal growth factor (EGF) is a small polypeptide (6,045 molecular weight) well recognized as a mitogen affecting a variety of cell types (see refs 1–3 for reviews). Its mitogenic effect is mediated through specific high-affinity receptors on the plasma membrane, and after ligand binding, some (but not all) cells respond in a variety of ways which lead to either increased growth rate or differentiation. Although the initial description of EGF by Cohen⁴ demonstrated a maturational influence on eye-opening and tooth eruption in newborn mice, there has been little investigation of the effect of EGF on developing fetal tissues. Nexo et al.⁵ have provided evidence that EGF and its receptors are present in mouse embryos as early as day 13 of gestation, especially in the secondary palate where EGF may have a role in palate closure, and EGF receptors have also been described in the human placenta⁶ and in fetal rabbit lung⁷. Thus, the limited data available suggest that EGF may play a part in fetal growth and development of specialized function. Here, we describe the binding and mitogenic activity of EGF both in vitro and in vivo in several fetal mouse tissues.