Development of the connective tissue network in the neonatal hamster heart

Abstract

The formation of the connective tissue network, composed principally of collagen, in the left ventricle of the neonatal hamster heart developed primarily during the first 20 days postpartum. The weave network of the endomysium, which was absent at birth, was visible by 4 days and was similar to that of the adult by 15 days postpartum. Myocyte-myocyte and myocyte-capillary struts formed gradually as the heart underwent physiological hypertrophy. These data were similar to the development of the connective tissue network in the rat except that the myocyte-myocyte struts were more numerous in the hamster. Presumably this is because the hamster has a higher heart rate, which would require more mechanical coupling of the myocytes. Formation of the struts appears to take place at precise areas on the sarcolemma through the interaction of collagenous and noncollagenous components of the extracellular matrix.

Basal Lamina of the Dermal Capillary: Concentric Multilamination Following Regeneration Processes

“…Studies using electron microscopy, culture, and specific antigens have shown that endothelial cells produce types III, IV and V (AB 2 ) collagen as well as fibroblasts and vascular smooth muscle cells (16)(17)(18). In addition, the regular arrangement of the collagenous fibrils around the vascular perimeter is thought to be controlled by the endothelium (8,19). In light of the spatial relationship of the delicate collagen fibrils between the two BL, where there are no cellular components, it can be postulated that the endothelial cells produce fibrillar collagen to some extent and under certain conditions.…”

Expression and accumulation of interstitial collagen in the neonatal rat heart

“…Alterations seen in the neonatal heart include, in part, myocyte hypertrophy, increases in active and passive tension, mean arterial blood pressure, and heart rate (Zak, 1973;Hopkins et al, 1973). Also prominent among the alterations that occur during this critical period of heart development are changes in the organization and accumulation of extracellular matrix (ECM) components, particularly interstitial collagens (Borg and Caulfield, 1979;Borg, 1982).…”

“…The connective tissue network of the vertebrate heart is composed predominantly of types I and I11 collagen fibers which form several distinct organized layers in the heart wall, similar to skeletal muscle, including the epimysium, perimysium, and endomysium (Borg and Caulfield, 1979;Borg, 1982;Borg et al, 1982Borg et al, , 1983. The endomysial layer consists of an elaborate weave network and collagen struts which connect adjacent myocytes and myocytes to capillaries.…”

Fine Structural Arrangement of Fibrous Stroma around Dermal Capillaries

“…It is obvious that the fibroblasts (veil cells) lay down most of the collagenous and elastic components of the vascular stroma; to some extent, the endothelium as well as pericytes may also produce them (1,2,20,21). The regular arrangement of the fibrils would represent order resulting from macromolecular interactions, presumably controlled by the endothelium (14,22).…”