Kierdorf Uwe, Stock Stuart R, Gomez Santiago, Antipova Olga, Kierdorf Horst
Department of Biology, University of Hildesheim, Universitätsplatz 1, 31141 Hildesheim, Germany.
Department of Cell and Developmental Biology, Feinberg School of Medicine, and Simpson Querrey Institute, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611-3008, USA.
Bone Rep. 2022 Apr 28;16:101571. doi: 10.1016/j.bonr.2022.101571. eCollection 2022 Jun.
Antlers are paired deciduous bony cranial appendages of deer that undergo a regular cycle of growth, death and casting, and constitute the most rapidly growing bones in mammals. Antler growth occurs in an appositional mode and involves a modified form of endochondral ossification. In endochondral bones, calcified cartilage is typically a transient tissue that is eventually completely replaced by bone tissue. We studied the distribution and characteristics of calcified cartilage in hard antlers from three deer species (, , ), i.e., in antlers from which the skin (velvet) had been shed. Remnants of calcified cartilage were regularly present as part of the trabecular framework in the late formed, distal antler portions in all three species, whereas this tissue was largely or completely missing in the more proximal antler portions. The presence of calcified cartilage remnants in the distal antler portions is attributed to the limited antler lifespan of only a few months, which is also the reason for the virtual lack of bone remodeling in antlers. The calcified cartilage matrix was more highly mineralized than the antler bone matrix. Mineralized deposits were observed in some chondrocyte lacunae and occasionally also in osteocyte lacunae, a phenomenon that has not previously been reported in antlers. Using synchrotron radiation-induced X-ray fluorescence (SR-XRF) mapping, we further demonstrated increased zinc concentrations in cement lines, along the inner borders of incompletely formed primary osteons, along the walls of partly or completely mineral-occluded chondrocyte and osteocyte lacunae, and in intralacunar mineralized deposits. The present study demonstrates that antlers are a promising model for studying the mineralization of cartilage and bone matrices and the formation of mineralized deposits in chondrocyte and osteocyte lacunae.
鹿角是鹿类成对的、会脱落的颅骨附属骨结构，经历定期的生长、死亡和脱落周期，是哺乳动物中生长最快的骨骼。鹿角以附加生长模式生长，涉及一种改良形式的软骨内成骨。在软骨内骨中，钙化软骨通常是一种暂时的组织，最终会被骨组织完全替代。我们研究了三种鹿（ 、 、 ）硬鹿角中钙化软骨的分布和特征，即已脱落皮肤（鹿茸）的鹿角。在所有这三个物种中，钙化软骨残余物作为小梁框架的一部分，定期出现在鹿角远端较晚形成的部分，而在鹿角近端部分，这种组织大多或完全缺失。鹿角远端部分存在钙化软骨残余物，这归因于鹿角只有几个月的有限寿命，这也是鹿角几乎缺乏骨重塑的原因。钙化软骨基质比鹿角骨基质矿化程度更高。在一些软骨细胞腔隙中观察到矿化沉积物，偶尔在骨细胞腔隙中也观察到，这种现象以前在鹿角中尚未有报道。使用同步辐射诱导X射线荧光（SR-XRF）映射，我们进一步证明，在黏合线、不完全形成的初级骨单位的内边界沿线、部分或完全被矿物质封闭的软骨细胞和骨细胞腔隙壁以及腔隙内矿化沉积物中，锌浓度增加。本研究表明，鹿角是研究软骨和骨基质矿化以及软骨细胞和骨细胞腔隙中矿化沉积物形成的一个有前景的模型。
