Development of pericyte-like cells during angiogenesis in quail chick chimeras as detected by combined Feulgen reaction and immunohistochemistry.

Perivascular fibroblasts have been proposed as possible precursor cells for microvascular pericytes. To investigate the development of pericytes during angiogenesis we examined interspecific grafts between chick and quail embryos. Limb buds of three-day old quail embryos were transferred to the chorioallantoic membrane (CAM) of ten to fourteen day-old chick embryos. Six days after grafting, the limb buds were explanted and histologically examined by combined Feulgen reaction and immunohistochemistry using an antibody to quail endothelial and hemopoietic cells (QH-1). Limb buds were found to be vascularized by a network of capillaries which were partially derived from sprouts of the chick CAM microvasculature. Numerous hybrid capillaries were detected, consisting of host endothelial cells (chick) and graft pericytes (quail). These results provide further support for the idea that microvascular pericytes can evolve from perivascular fibroblasts.