An ultrastructural study of developing extracellular matrix in vitelline blood vessels of the early chick embryo

Abstract

This investigation was designed to describe the morphological events in embryonic development of peripheral blood vessels (vasculogenesis) and to relate this process to the appearance of extracellular matrix (ECM) during growth and maturation of these tissues. Extraembryonic vitelline vessels of the early chick embryo were chosen for this study and light, transmission, and scanning electron microscopy were carried out on vessels excised from chick embryos (Hamburger-Hamilton stages 8 through 23). Our data show that early (stage 10) vessels are composed of two distinct epithelial layers, an inner layer of presumptive endothelium surrounded by a layer of splanchnopleuric mesoderm. During development, the inner layer gives rise to mature vascular endothelium while splanchnopleuric mesoderm differentiates to form primitive vascular smooth muscle. Ultrastructural studies show the presence of collagen and basal lamina in the extracellular space between these two layers during initiation of endothelial and smooth muscle cytodifferentiation. Furthermore, ruthenium red-positive material is present on basal surfaces of developing vascular endothelium at this time, indicating possible glycosaminoglycans (GAG) or other polyanionic components of the ECM. These data suggest that the sequential production of basal lamina, collagen (s), and/or GAG's by developing peripheral vessel wall epithelia may be critical to their final differentiation.

Notch mediates Wnt and BMP signals in the early separation of smooth muscle progenitors and blood/endothelial common progenitors

“…A similar model for the early separation of cells contributing to the BC/EC lineage and cells contributing to the extraembryonic coelomic linings was proposed by Sabin (Sabin, 1920), although the SMC nature of coelomic lining cells was not clearly mentioned in that report. The general anatomical organization, proposed in this work, of the extraembryonic mesoderm in the chick embryo, is also supported by ultrastructural studies (Kessel and Fabian, 1985;Murphy and Carlson, 1978).…”

“…1A). The BC/EC progenitors aggregate to form blood islands within the extraembryonic splanchnic mesoderm, which contains in addition vascular SMCs (Kessel and Fabian, 1985;Murphy and Carlson, 1978;Sabin, 1920). The extraembryonic somatic mesoderm gives rise to mesothelial cells lining the ectoderm, from which the amnionic and chorionic membranes are derived (Adamstone, 1948;Oppenheim, 1966;Pierce, 1933;Romanoff, 1960;Wu et al, 2001).…”

Primitive and definitive erythropoiesis in the yolk sac: a birds eye view

“…The splanchnic wall of the extraembryonic coelom is the source of cells for the vascular smooth muscle layer during vasculogenesis, and after formation of the vascular network, vascular smooth muscle layer is in direct contact with the extraembryonic coelomic cavity. This general organization of somatopleural and splanchnopleural tissues in the yolk sac is supported by ultrastructure studies (Kessel and Fabian, 1985;Murphy and Carlson, 1978).…”

Developmental Biology of the Vascular Smooth Muscle Cell: Building a Multilayered Vessel Wall

“…For many years, differentiation and maturation of VSMCs has been correlated to changes in the ECM composition of the vessel wall. Studies from Murphy and Carlson [216]suggested that ultrastructural differentiation of presumptive VSMCs occurs concomitantly with synthesis of specific ECM proteins. Within early embryonic chicken vitelline vessels (embryonic days 1–4) two distinct cell layers, representing the early endothelium and presumptive VSM, are observed in the vessel wall by transmission electron microscopy at stage 10, no ECM material is apparent.…”