Ghazi S R, Gholami S
Department of Anatomy, School of Veterinary Medicine, Shiraz University, Iran.
J Anat. 1994 Oct;185 ( Pt 2)(Pt 2):427-31.
Allometric growth of the spinal cord in relation to the vertebral column was studied for the whole cord and for regional and segmental levels in 30 Iranian sheep of the Mehraban breed, divided into 5 groups comprising 3, 4 and 5 month fetuses, new born lambs, and adults, each group consisting of 6 animals. Observations in all 5 age groups revealed that although the growth of the vertebral column was greater than that of the spinal cord, the difference in growth was limited to the lumbar region and other more caudal regions. The most marked change was observed in the coccygeal region. The growth rate of the coccygeal vertebral column when compared with that of the spinal cord in this region was 2.27, 4.16, 4.76, 4.54 and 7.69 times in the 3, 4, 5 month fetuses, new born lambs and adult sheep, respectively. The allometric growth rate for individual regions indicated that in the cervical region in all age groups, the highest growth rate was at the level of C1 and the lowest at C6 and C7 vertebrae. In the thoracic region, it was higher in the caudal than the cranial part. In the lumbar and sacral regions, growth rate decreased craniocaudally. As a consequence of the negative allometric growth of the spinal cord in relation to the vertebral column in the caudal half of spine, the conus medullaris was displaced from S4 or 3 vertebrae in the 3 month fetus to S2 in adult sheep.
研究了30只梅拉班品种的伊朗绵羊整个脊髓以及区域和节段水平上脊髓相对于脊柱的异速生长情况。这些绵羊分为5组，分别为3个月、4个月和5个月大的胎儿、新生羔羊和成年羊，每组6只动物。对所有5个年龄组的观察表明，虽然脊柱的生长大于脊髓，但生长差异仅限于腰椎区域和其他更靠尾端的区域。尾骨区域观察到的变化最为明显。与该区域脊髓相比，尾骨脊柱在3个月胎儿、4个月胎儿、5个月胎儿、新生羔羊和成年羊中的生长速率分别为2.27倍、4.16倍、4.76倍、4.54倍和7.69倍。各个区域的异速生长率表明，在所有年龄组的颈部区域，C1水平的生长速率最高，C6和C7椎体水平的生长速率最低。在胸部区域，尾端的生长速率高于头端。在腰部和骶部区域，生长速率从颅侧向尾侧降低。由于脊柱后半部分脊髓相对于脊柱的负异速生长，脊髓圆锥从3个月胎儿时的S4或S3椎体移位到成年羊的S2椎体。
