The ossification process of primary antlers was studied in five fallow
bucks aged about ten months. In the growing primary antler the follow
ing tissue zones could be distinguished histologically in a disto-prox
imal direction: a proliferative zone, a zone of cartilage maturation a
nd hypertrophy, a zone of cartilage mineralization and degeneration, a
zone of primary spongiosa and a zone of secondary spongiosa. Although
the strict disto-proximal zonation of tissue changes typical for endo
chondral ossification of somatic cartilage was not seen in primary ant
ler formation, the histological and histochemical findings clearly dem
onstrated that this process can be best described as a modified form o
f endochondral ossification. Our study produced no evidence for a dire
ct (metaplastic) conversion af cartilage into bone during primary antl
er development. Generally, the histogenesis of primary antlers closely
resembles the process of secondary antler growth as described by othe
rs. Minor differences between the two processes can be ascribed to the
fact that during secondary antler formation a much bigger structure h
as to be built up in an even shorter time span than in the case of pri
mary antler development and, therefore, the processes of cartilage for
mation, cartilage destruction and bone remodelling interdigitate even
more closely during subsequent antler growth, compared to that of prim
ary antlers. Our study clearly revealed that the transition from pedic
le to first antler growth in fallow deer cannot be defined as a change
in the ossification pattern, as was previously assumed for cervids in
general.