A histological and histochemical study of biopsy specimens from the Lapland reindeer antler indicated that the intercellular matrix of the cartilage that forms the partitions of longitudinal channels becomes calcified at virtually the initial stage of formation. The lacunae at the peripheries of the cartilaginous partitions are invaded by osteoblasts in a process comparable to endochondral ossification. The very centres of the partitions evidently become directly converted into bone without the presence of e.g. osteoclasts. The osseous partitions are remodelled by osteoclasts. The antler increases in diameter by periosteal apposition.

gene-related peptide 278 Casting 109

Alkaline phosphatase activity increased 10,000‐fold over basal levels in reindeer antler during the period of massive growth. The activity was highest in the zone of differentiating chondrogenic cells in the growing tip. The activity in the shaft was lower. PPiase activity was also highest in the antler tip, but compared to alkaline phosphatase, was more tightly membrane‐bound. Ca2+, Mg2+‐ATPase activity was not so markedly elevated in the tip as were the other activities. During the growth cycle, the highest activities of acid phosphatase and amino peptidases occurred later than the peak of alkaline phosphatase activity, and were found mainly in the dermis of the shaft. Abstracting Keywords: Antler (reindeer)Growth cycleAlkaline phosphataseAcid phosphataseAminopeptidase Notes Institute of Dentistry, University of Oulu, 90220 Oulu 22, Finland. Finnish Game and Fisheries Research Institute, 96100 Rovaniemi 10, Finland.