PATHOLOGICAL AND ENZYME HISTOCHEMICAL-STUDIES ON BONE-FORMATION INDUCED BY BONE MORPHOGENETIC PROTEIN IN MOUSE MUSCLE-TISSUE

Bone morphogenetic protein (BMP) irreversibly induces the differentiation of mesenchymal-type cells intoosteoprogenitor cells for endochondral ossification. During the process of BMP-induced differentiation in mice, 4 cell types (chondroblasts, osteoblasts, chondroclasts, and osteoclasts) were examined for phosphatase and succinate dehydrogenase using a wide range of buffers (4.0 ≤pH ≤ 9.2). During the chondroid tissue-forming stage (1 week), chondroblast-like or osteoblast-like cells expressedphosphatase activity at 6.8 ≤ pH ≤ 9.2; chondroclast-like or osteoclast-like cells expressed phosphatase activity at 4.0 ≤ pH ≤ 5.8. However, mature chondrocytes found in hyaline cartilage expressed phosphatase activity between 6.6 ≤ pH ≤ 7.6 (2 weeks). During the process of endochondral ossification, alkaline phosphatase activity decreased in osteoblast-like cellswith traces of acid phosphatase activity still detectable. Chondroclastic and osteoclastic giant cells were characterized by intense succinate dehydrogenase activity. © 1990, VEB Gustav Fischer Verlag Jena. All rights reserved.