TOXOPLASMOSIS: MORPHOLOGICAL AND MORPHOMETRIC EVALUATION OF SPINAL CORD NEURONS FROM NONSYMPTOMATIC SEROPOSITIVE DOGS

The aim of this work was to analyze the neuron morphology and morphometry of cervical, thoracic and lumbar areas of nonsymptomatic seropositive dogs’ spinal cord for toxoplasmosis. Twenty indefinite-breed adult dogs were used; ten dogs were healthy, with negative serology for toxoplasmosis, and were used as the control group (group 1), and ten dogs were nonsymptomatic but seropositive for toxoplasmosis (group 2). After the microtomy, with interval of 100 micrometers (µm), the histological 5-µm-thick cuts were dyed by hematoxylin-eosin and Masson's trichrome techniques. The glass slides were analyzed under light microscope to examine the neuron morphology. The parameters considered for the morphometric analysis were area, perimeter, maximum diameter, minimum diameter and shape factor of cytoplasm and nucleus of neuron. The results were statistically analyzed by Student’s t test at 5% probability level. The morphological characteristics between the two groups were similar and according to literature. The morphometric results showed that there were changes in neurons size and structure, and increase and loss of star shape were noticed in seropositive animals. The results suggest that the neurons of these dogs, yet nonsymptomatic, can have lost their conductor function.

本研究旨在分析无症状弓形虫血清阳性犬脊髓颈、胸、腰段的神经元形态与形态计量学特征。本研究选用20只成年未明确品种犬，其中10只为弓形虫血清学阴性的健康犬，作为对照组（组1）；另外10只为无症状但弓形虫血清阳性犬（组2）。经组织切片处理后，以100微米（µm）为间隔切取5微米厚的组织切片，并采用苏木精-伊红染色法与马松三色染色法完成染色。随后在光学显微镜下对载玻片进行观察，以评估神经元形态。本次形态计量分析的考察参数包括神经元胞质与胞核的面积、周长、最大直径、最小直径及形状因子。采用学生t检验（显著性水平设为5%）对结果开展统计学分析。结果显示，两组间的神经元形态学特征相似，且与现有文献报道一致。形态计量结果表明，血清阳性动物的神经元大小与结构发生改变，可见星形结构的增大与缺失。本研究结果提示，这些犬只虽无临床症状，但其神经元或已丧失传导功能。