Sims D, Horne M M, Creighan M, Donald A
Department of Anatomy and Physiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Canada.
Anat Histol Embryol. 1994 Sep;23(3):232-8. doi: 10.1111/j.1439-0264.1994.tb00472.x.
The objective of this ultrastructural investigation was to determine if populations of pericytes in equine dermal and skeletal muscle capillaries increase in a head-to-foot direction, as has been reported in human skeletal muscles. Samples of equine microvessels were obtained from the longissimus dorsi skeletal muscle 150 cm. from the ground, from the dermis above this muscle, from the extensor carpi radiali muscle at 55 cm. from the ground, from the dermis adjacent to that muscle, and from dermis 15 cm. from the ground, just above the hoof wall. Tissues were processed for transmission electron microscopy. Electron micrographs were analyzed with a digitizing tablet and computer, to determine the ratios of endothelial cell outer circumference and pericyte inner lengths. Pericytes were separated into two classes; those closest to the endothelial cells were defined as covering capillaries. Those separated from endothelial cells by another layer of pericytes were termed enveloping pericytes. There was much greater coverage and envelopment of dermal capillaries (85% and 135%) than skeletal muscle capillaries (27% and 31%). Regression analysis of the pericyte coverage and envelopment of dermal capillaries revealed a significant increase in pericytes toward the ground. Similarly, the two skeletal muscle tissues differed significantly in their pericyte coverage and envelopment (25/27% at 150 cm., 31/35 at 55 cm.). The data indicate that, as in humans, capillary pericytes are not homogeneously distributed within the same tissues, but are more numerous closer to the ground. Differences in pericyte populations could affect studies of microvessel function.
这项超微结构研究的目的是确定马的真皮和骨骼肌毛细血管中的周细胞数量是否如人类骨骼肌中所报道的那样，从头部到脚部方向增加。从距地面150厘米处的背最长肌骨骼肌、该肌肉上方的真皮、距地面55厘米处的桡侧腕伸肌、该肌肉相邻的真皮以及距地面15厘米处蹄壁上方的真皮中获取马微血管样本。对组织进行透射电子显微镜处理。用数字化平板和计算机分析电子显微照片，以确定内皮细胞外周长度与周细胞内长度的比率。周细胞分为两类；最靠近内皮细胞的那些被定义为覆盖毛细血管。被另一层周细胞与内皮细胞隔开的那些被称为包绕周细胞。真皮毛细血管的覆盖和包绕程度（85%和135%）比骨骼肌毛细血管（27%和31%）大得多。对真皮毛细血管周细胞覆盖和包绕的回归分析显示，周细胞数量朝着地面方向显著增加。同样，这两个骨骼肌组织在周细胞覆盖和包绕方面也有显著差异（150厘米处为25/27%，55厘米处为31/35%）。数据表明，与人类一样，毛细血管周细胞在同一组织内分布不均匀，在靠近地面处数量更多。周细胞数量的差异可能会影响微血管功能的研究。
