The influence of epithelia on cartilage and loose connective tissue formation by limb mesenchyme cultures

• Published in: Developmental biology Vol. 86; no. 2; pp. 471 - 482
• Main Authors: Solursh, Michael, Singley, Carl T., Reiter, Rebecca S.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-09-1981
• Subjects: Animals; Cartilage - cytology; Cartilage - embryology; Cell Differentiation; Cells, Cultured; Chick Embryo; Collagen - metabolism; Connective Tissue - embryology; Connective Tissue Cells; Ectoderm - physiology; Epithelium - physiology; Wings, Animal - physiology
• ISSN: 0012-1606; 1095-564X
• DOI: 10.1016/0012-1606(81)90205-0

In order to explain the observation that normally nonchondrogenic limb mesenchyme forms extensive cartilage in culture, the possibility that limb ectoderm inhibits chondrogenesis is examined. Small pieces of quail or chick ectoderm are grafted onto micromass cultures of wing mesenchyme from stage 23–34 chick embryos. The presence of nonridge wing or several other epithelia results in increased collagen accumulation in the underlying mesenchyme, a delay in cell differentiation, and the eventual formation of loose connective tissue, as determined by transmission electron microscopy. The influence can occur across Nuclepore filters having 0.1-μm-diameter pores and ultrathin Millipore filters, but not across Millipore filters of standard thickness. The influence is not contact dependent since cell processes do not cross these filters. The apical ectodermal ridge has the additional effect of stimulating mesenchymal outgrowth. These results support the idea that the ectoderm plays a direct but negative role in the formation of a chondrogenic core within the developing limb.