Hematopoiesis in Bovine Heart Bone

Abstract

ABSTRACT. In the bovine heart, chondrification of the fibrous tissue occurs just after birth and proceeds to bony tissue. The ossification appears first in the right fibrous trigonum three months after birth and then in the left trigonum twelve months after birth. During ossification, the bone marrow structure appears to form a narrow space within the bony tissue and develops during the subsequent year. Light and electron microscopic examinations revealed development of typical hematopoiesis in the heart bone marrow. Hemoglobin was estimated in various erythroid cells by cytospectral analysis. The hematopoietic activity was retained for about 10 years in the heart bone.The presence of cartilage in the heart has been known in man (2) and in vertebrates, e.g., the cow (6, 8), hamster (5), rat (3, 4), bird (8) andeven in the frog (1) and fish (8). In most animals, cartilage appears in peculiar loci of the heart. However, the heart bone was observed as an ossified plate in the fibrous annulus surrounding the base of the aorta (8, 9). In rare cases of avian heart (8), chondrification forms a bony piece involving bone marrow space. The details on the formation of heart bone marrow structure have yet not been described. In dissections of many bovine hearts, we found bone marrow structures and have elucidated the hematopoiesis in the structures. This paper also reports on heart bone hematopoiesis at various age periods by cytospectral analysis of erythroid cells. MATERIALS AND METHODSTwenty-seven hearts were dissected from domestic Bos at sacrifice. The examined age range was from newborn to 10 years old and consisted of males, females and castrated males ( Table 1). The heart bones were carefully resected from the base of the aorta and pulmonary trunk. The resected bones were cut into small pieces and fixed with 2.5 % glutaraldehyde in 0.1 M phosphate buffer, pH, 7.2, for 1 h at 4° C and examined by electron microscopy. For ordinary histologic examination, the bony pieces were fixed with 10% formalin in 0.1 M phosphate buffer, pH 7.2, then decalcified with 2 % citric acid solution saturated with EDTA-2Na for several days and postfixed with Zenker's fluid. The tissueswere embedded in celloidin-paraffin, sectioned at 15,u and stained with hematoxylin and eosin. The cut face of the raw bone was stamped on a glass slide, dried, fixed with methanol and prepared by Wright stain for blood cell diagnosis. Some samples were applied for cytospectral identification of immature erythrocytes. Cytospectral analysis was carried out by the relative wavelength-scanning method, 353

In Vivo and In Vitro Cartilage Differentiation from Embryonic Epicardial Progenitor Cells

“…The possible functions of cardiac cartilage have been extensively discussed, although no clear conclusions are to be found in the literature. Remarkably, in some vertebrate taxa such as bovines, chondrification events were described at perinatal stages in physiological, spontaneous conditions [ 20 ]. This is the case of cardiac cartilage development in the chick: while aorta and pulmonary valve chondrocyte clusters (neural crest derived) differentiate at embryonic stages, the new-described PE-derived LOT cluster described in our work differentiates at perinatal stages.…”