Altered collagen fibrillogenesis in embryonic mouse limb cartilage deficient in matrix granules

• Published in: Experimental cell research Vol. 102; no. 1; pp. 213 - 222
• Main Authors: Kochhar, D.M., Aydelotte, M.B., Vest, T.K.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.10.1976
• Subjects: Animals; Cartilage - metabolism; Cartilage - ultrastructure; Collagen - metabolism; Connective Tissue - ultrastructure; Connective Tissue Cells; Diazooxonorleucine - pharmacology; Endoplasmic Reticulum - ultrastructure; Glycogen; Golgi Apparatus - ultrastructure; Hydroxyproline - biosynthesis; Mice; Uronic Acids - biosynthesis
• ISSN: 0014-4827; 1090-2422
• DOI: 10.1016/0014-4827(76)90317-7

In an effort to study interactions between the two major components of connective tissue matrix, collagen and proteoglycans, we have investigated the nature of collagen fibrils deposited in situ under conditions that reduce the content of uronic acid-containing polymeric material in developing mouse limb bud cartilage. Here we report some ultrastructural features of cartilage matrix organized under conditions that are known to inhibit synthesis of glycosaminoglycans. Limb buds of 12th day mouse embryos (40 ± 2 somites) were explanted in organ culture in the presence or absence of 5 μg/ml DON (6-diazo-5-oxonorleucine), a glutamine analogue. A pronounced decrease in the level of uronic acid-containing polymeric material was found in DON-treated explants over the 6-day culture period. Ultrastructural features of chondrocytes and lack of large matrix granules from the DON-treated cartilage provided confirmatory evidence that the matrix was deficient in glycosaminoglycans. No decrease in the hydroxyproline content was found in the treated explants. In contrast to the cartilage matrix of untreated explants, the matrix of DON-treated cartilage consisted entirely of a dense meshwork of fibrils. An enhancement of collagen fibrillogenesis was noticed at the surface of treated chondrocytes; fibrils were atypically arranged in parallel arrays and were larger in diameter than those found in the untreated cartilage of limb buds at identical stages of development and differentiation. Cross-striation pattern was detectable at several sites along these large fibrils. It is proposed that DON-treatment interferes with factors that regulate the growth phase of fibril formation resulting in alterations in the width of fibrils.