Journal of Aquaculture Research & Development

Abstract

New Aspect in Cartilage Growth “The Invasive Interstitial Type”

Soha A Soliman

Growth of hyaline cartilage is achieved either by chondrocyte division “interstitial type of growth” or by perichondrial cell differentiation of mesenchymal cells to differentiated chondrocytes which deposit successive circumferential layers of cartilage matrix “appositional growth”. The current study was carried out to illustrate a third type of cartilage growth during development of the air breathing dendritic organ of catfish. To perform this study, samples of the air breathing dendritic organ were collected from catfish (Clarias garie-pinus). Paraffin sections of formalin fixed specimens were examined by light microscopy. During development of the air breathing organ of catfish, the nidus of cartilage formation was represented by a condensation of mesenchymal cells. Some cells differentiate to chondrocytes to form multiple cartilage islets surrounded by mesenchymal tissue which was enclosed by perichondrium. The surrounding mesenchymal cells further on differentiate to chondrocytes to complete the developing elastic cartilaginous unit. Additional mesenchymal cells with chondrocyte potential invade the cartilage at multiple sites to grow the cartilaginous mass interstitially. Moreover, interstitial mesenchymal differentiation occurred at the sites of the vacated lacunae which resulted from the death of chondrocytes and then replaces the hyaline. Interstitial mesenchymal invasion occurred in the hyaline cartilage to be replaced by elastic type. The invasive interstitial differentiation of the mesenchymal cells contributed in cartilage growth, renewal, and replacement. Studying the molecular regulation of the invasive differentiation of the mesenchymal cells may be a useful guide in researches to resolve cartilage disorders problems.