VASCULARIZATION OF EMBRYONIC ADRENAL-GLAND GRAFTED ONTO CHORIOALLANTOIC MEMBRANE

Vascularization and endothelial phenotype expression were analysed in embryonic adrenal tissue grafted onto chorioallantoic membrane (CAM), by means of routine light microscopy and immunocytochemical staining, and of electron microscopy. Adrenal gland tissue from chick or quail e mbryos (donors) was grafted onto CAMs of chick or quail embryos (host) . Vessels of chick origin were discriminated from those of quail origi n by monoclonal antibodies, anti-MB1, specific for quail endothelial a nd haemopoietic cells, and QCPN, which labels quail cell nuclei. Vesse ls of adrenal type were distinguished from those of CAM-type by their ultrastructural endothelial phenotype - porous in the former and conti nuous in the latter. The observations carried out 6 days after implant ation indicate that the adrenal gland develops and differentiates acco rding to a virtually normal histological pattern. As regards the adren al and CAM vascularization, the grafting procedure elicits angiogenic events consisting in the formation of peripheral anastomoses between t he graft and the CAM original microvasculature and in new-growth of ve ssels from the CAM into the grafted tissue and vice versa. As to the e ndothelial phenotype, the ultrastructural results demonstrate that bes ides its own native vasculature, the adrenal tissue contains vessels w ith continuous endothelium and the CAM mesenchyme is supplied by adren al-type, fenestrated vessels.