Stanley R L, Goodship A E, Edwards B, Firth E C, Patterson-Kane J C
Department of Pathology and Infectious Diseases, The Royal Veterinary College, Hatfield, Hertfordshire AL9 7TA, UK.
Equine Vet J. 2008 Mar;40(2):141-6. doi: 10.2746/042516408X266097.
The injury-prone, energy-storing equine superficial digital flexor tendon (SDFT) of the mature performance horse has a limited ability to respond to exercise in contrast with the noninjury-prone, anatomically opposing common digital extensor tendon (CDET). Previous studies have indicated low levels of cellular activity in the mature SDFT, but in foal tendons the tenocytes may still have the ability to adapt positively to increased exercise.
To measure tenocyte densities and types in histological sections from the SDFT and CDET of horses from controlled long-term, short-term and foal exercise studies.
Specimens were collected from mid-metacarpal segments of the CDET and SDFT for each horse and processed for histology; central and peripheral regions of the SDFT cross-section were analysed separately (SDFTc, SDFTp). Tenocyte nuclei were counted in a total area of 1.59 mm(2) for each tendon region in each horse. Each nucleus was classified as type 1 (elongate and thin), type 2 (ovoid and plump) or type 3 (chondrocyte-like); type 1 cells are proposed to be less synthetically active than type 2 cells.
No significant differences were noted between exercise and control groups in any of the studies, with the exception of an exercise-related reduction in the proportion of type 1 tenocytes for all tendons combined in the long-term study. There were tendon- and site-specific differences in tenocyte densities and proportions of type 1 and 2 cells in all 3 studies.
There was no indication that exercise increased tenocyte density or proportions of the (theoretically) more active type 2 cells in immature horses (short-term and foal studies), perhaps because the training regimens did not achieve certain threshold strain levels. In the foal study these findings can still be interpreted positively as evidence that the training regimen did not induce subclinical damage.
与不易受伤、解剖结构相对的指总伸肌腱（CDET）相比，成熟运动马匹易受伤、储能的指浅屈肌腱（SDFT）对运动的反应能力有限。以往研究表明，成熟SDFT中的细胞活性水平较低，但在马驹肌腱中，腱细胞仍可能有能力积极适应运动量的增加。
在长期、短期和马驹运动对照研究中，测量马匹SDFT和CDET组织学切片中的腱细胞密度和类型。
采集每匹马CDET和SDFT掌骨中段的样本进行组织学处理；分别分析SDFT横截面的中央和外周区域（SDFTc、SDFTp）。对每匹马每个肌腱区域1.59平方毫米的总面积内的腱细胞核进行计数。每个细胞核分为1型（细长）、2型（卵圆形且饱满）或3型（软骨样）；据推测，1型细胞的合成活性低于2型细胞。
除长期研究中所有肌腱合并后1型腱细胞比例出现与运动相关的降低外，在任何一项研究中，运动组和对照组之间均未发现显著差异。在所有三项研究中，腱细胞密度以及1型和2型细胞的比例存在肌腱和部位特异性差异。
没有迹象表明运动增加了未成熟马匹（短期和马驹研究）中腱细胞的密度或（理论上）更活跃的2型细胞的比例，这可能是因为训练方案未达到特定的阈值应变水平。在马驹研究中，这些发现仍可被积极地解释为训练方案未诱发亚临床损伤的证据。
