Humerus Primer Ossification Zone Development in Rat Fetuses: A Histological and Histochemical Study


Abstract: In this investigation of the primary ossification zones of 14-18 day-old fetal rat humeri by histological, histochemical and histoenzymatical methods, 30 rat fetuses of the species Rattus norvegicus were used. The humeral diaphysis samples of the fetuses were subjected to alcian blue-heamatoxylin, periodic acid Schiff (PAS)-heamatoxylin, alcian blue-PAS-heamatoxylin, alizarin red and toluidine blue, alkaline phosphatase (ALP), adenosine triphosphatase (ATPase) and acid phophatase (ACP) staining techniques. The results can be summarized as follows: On day 14, no ossification signs were evident yet, whereas on day 15, the initiation of degenerations in some chondrocyte cytoplasms and the formation of osteoblastic cells on periphery of the cartilage model were observed. On day 16, for the 1st time the formation of an acellular zone (osteoid) between the osteoblastic cell layer and the diaphysis chondrocytes was visible. On day 17, in the diaphysis matrix, which was almost dispersed, all of the enzyme activities being studied were prominent. And on day 18, rich vascular elements were evident between and around the ossified trabeculae. According to these results, primary ossification in the humerus cartilage model of the rat appears to begin on day 16 and various phosphatases may play important roles in the ossification process.

Keywords: Rat, Prenatal, Ossification, Humerus, Phosphatase

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