The distribution of glycosaminoglycans in the axial region of the developing chick embryo. I. Histochemical analysis

Abstract

Histochemical analysis of the developing chick axial region indicated very little sulphated glycosaminoglycan present in early embryonic stages (stage 17) and this appeared to be confined extra-cellularly to the region of the notochordal sheath. Strongly acidic material was observed in the cytoplasm of cells in all examined axial areas, viz., dermatome, myotome, sclerotome, neural tube and notochord. Weakly acidic anionic glycosaminoglycans were present i n the extracellular portion of all axial areas and increased in concentration during development, particularly i n the neural tube and the sclerotome. At the same time the concentration of sulphated anionic glycosaminoglycans also increased in the extracellular matrix of all axial areas. By stage 25 the extracellular matrix of the perichordal scleratome appeared to

Retention during embryonic life of the ability of avian spinal cord to induce somitic chondrogenesis <i>in vitro</i>

“…Maximal growth potential and cell viability has to be sacrificed in order to eliminate spontaneous chondrogenesis. That these supplements to the medium may be acting in vitro as do the spinal cord and notochord in vivo, is consistent with the recent observations that an extracellular matrix of glycosaminoglycans and collagen surrounds the notochord and spinal cord [Johnston and Comar, 1957;Kvist and Finnegan, 1970: Bazin and Strudel, 1972Carlson and Upson, 1974], and that enzymatic removal of that matrix renders the noto chord and spinal cord incapable of inducing somitic chondrogenesis [Kosher and Lash. 1975;Kosher, 1976], The supplements may mimic the action of this extra cellular material.…”

Abnormalities of cells and extracellular matrix of T/T embryos

“…Proteoglycans, especially hyaluron-ate and chondroitin sulfate, occur widely [9,30,321. Different collagen types are found in basement membranes [ l a and in the sheaths of the neural tube and notochord [6, 211. Although it is not clear how all the constituents of the ECM interact in influencing cell shape and the movements and attachments of cells during normal embryogenesis, a variety of evidence increasingly implicates the ECM in cell migration [6,18,30,32,351 and differentiation [8,17,19,351.…”

The effect of hyaluronan on mouse intramembranous osteogenesis in vitro

“…HA has by far the highest molecular weight of the GAGs (it ranges from 10 4 to 10 7 ) and is thought to facilitate cell migration during tissue morphogenesis and repair. Since the early 1970s, with the works of Kvist and Finnegan (1970) and of Toole and Gross (1971), HA has been found in variable amounts in all tissues and fluids of adult animals and is especially abundant in early embryos. Because of its simplicity, HA is thought to represent the earliest evolutionary form of GAG.…”