Mori Ryoichi, Kodaka Tetsuo, Soeta Satoshi, Sato Jun, Kakino Jun, Hamato Shohei, Takaki Hisashi, Naito Yoshihisa
Department of Oral Anatomy, Showa University School of Dentistry, Tokyo, Japan.
J Vet Med Sci. 2005 Dec;67(12):1223-9. doi: 10.1292/jvms.67.1223.
Some young large farm animals show a laminar bone formation in the long-bone cortex. Such a laminar bone is gradually replaced by Haversian bone with osteons during their growth periods. In this preliminary study, we observed the transverse ground samples of tibia cortex in young calves, pigs, and sheep by backscattered electron imaging. The cortex bones of all the newborn (NB) animals were basically formed with laminar bone structures. The NB and 1-month-old (1-M) calves had a typical concentric structure of laminar bone, whereas the NB and 1-M pigs showed a wire-netting bone with laminar-bone units. The NB sheep was similar to the calf rather than the pig. In the growth rate of bone volume, sheep was similar to calf up to 6 months after birth (6-M). Such calf and sheep showed a more rapid ratio of bone volume than pig. A few osteons had initially appeared in the innermost layer of the 6-M calf. A 1-year-old (1-Y) calf showed scattered osteons in the bone cortex, but many laminar-bone units were still retained in the outer layer. A 6-M pig had many osteons in the entire cortex but only a few osteons in the outermost layer. In the 6-M sheep, no osteons were observed, whereas a 1-Y sheep showed a relatively small number of osteons mainly in the middle layer but a higher osteon-volume than the 1-Y calf. In the 1-Y sheep, the more widely absorbed areas by bone-remodeling with osteons were observed as compared with the 1-Y calf, and the bone volume was decreased from the 6-M into the 1-Y sheep because of the remarkable bone-absorption. Thus, calf kept on possessing many laminar-bone units for a longer time in the growth period than sheep, while pig showed the earliest bone-remodeling with osteons. These results may be caused by their different body size and withers height in calf and sheep after growing and the difference of the dependence upon mother's body during juvenile period between pig and calf with sheep. The initial region of osteon formation may be distinguishable among their animals, respectively. However, further detailed investigations of their young animals at successive stages will be necessary.
一些幼年大型农场动物的长骨皮质中会出现板层骨形成。在其生长期间，这种板层骨会逐渐被带有骨单位的哈弗斯骨所取代。在这项初步研究中，我们通过背散射电子成像观察了幼年小牛、猪和绵羊胫骨皮质的横向磨片样本。所有新生（NB）动物的皮质骨基本上都是由板层骨结构形成的。新生和1月龄（1-M）的小牛具有典型的板层骨同心结构，而新生和1-M的猪则呈现出带有板层骨单元的网状骨。新生绵羊与小牛相似，而非猪。在骨体积生长速率方面，绵羊在出生后6个月（6-M）前与小牛相似。这样的小牛和绵羊的骨体积比猪增长得更快。在6-M的小牛最内层最初出现了一些骨单位。1岁（1-Y）的小牛在骨皮质中有散在的骨单位，但外层仍保留许多板层骨单元。6-M的猪在整个皮质中有许多骨单位，但最外层只有少数骨单位。在6-M的绵羊中未观察到骨单位，而1-Y的绵羊主要在中层有相对较少的骨单位，但骨单位体积比1-Y的小牛高。在1-Y的绵羊中，与1-Y的小牛相比，观察到骨重塑对骨吸收的区域更广泛，并且由于显著的骨吸收，骨体积从6-M到1-Y的绵羊中有所减少。因此，小牛在生长期间比绵羊更长时间地保留许多板层骨单元，而猪则最早出现骨单位的骨重塑。这些结果可能是由于小牛和绵羊生长后不同的体型和肩高，以及猪与小牛和绵羊在幼年期对母体依赖程度的差异所致。骨单位形成的初始区域在这些动物之间可能分别是可区分的。然而，有必要对其幼龄动物在连续阶段进行进一步详细的研究。
