雄性黄鼬直针毛无髓段的特点

Characteristics of Medulla Absent Part of Guard Hair for Male Siberian Weasel

利用普通钢尺测定了黄鼬东北亚种(Mustelasiberia manchurica)雄性成年个体头部、背中部、腹部、臀部、尾部直针毛毛长度,用显微测微尺测量毛尖无髓段和毛根无髓段长度,并计算出占整根毛长度的比例:腹部直针毛毛尖无髓段长度为(1.23±0.51)mm,占毛长的比例为(5.89±2.94)%,毛根无髓段长度为(0.96±0.18)mm,占毛长比例为(4.51±1.22)%,这两个指标均在一些个体之间有显著差异,而在另一些个体之间差异不显著,毛尖无髓段长度在个体间的变异较大。同一个体的头部、背中部、腹部、臀部和尾部的直针毛毛根无髓段长度均值(0.85±0.15)mm,部位之间差异不显著;毛尖无髓段长度为(1.09±0.66)mm,部位间差异显著。测定结果提示:毛在生长阶段髓质细胞开始分生的时间可能滞后于皮质细胞,而其结束的时间早于皮质细胞;相对于皮质细胞,髓质细胞结束分生的时间在身体不同部位比较统一;毛尖无髓段长度在身体部位之间的变异显示,不同部位直针毛毛尖受到的磨损程度不同,而且也因个体而异。

A medulla absent region （MAR） exists in the tip and root region of mammalian guard hair. The length and ratio of MARs of guard hair from head, mid back, belly, hip and tail regions of male adult Siberian weasel （Mustela siberia manchurica） were measured by common steel rules and micrometers. Results indicate that the mean length of tip MAR was （ 1.23 ± 0.51 ）mm, occupying 5.89% ± 2.94% of the whole hair length, and the mean length of root MAR was （0.96 ± 0.18 ）mm, occupying 4. 51% ± 1.22% of the whole hair length. The variation of the two parameters was significant among some individuals and not significant among others, but tip MAR had higher variation. The mean length of root MAR from head, mid back, belly, hip and tail regions of the same individual was （0. 85 ±0. 15）mm, revealing insignificant variation among body sites. The mean length of tip MAR was （ 1.09 ± 0.66） mm, displaying significant variations among body sites. Results indicate that the onset of differentiation of medullar cells is possibly later than that of cortex ceils, but its termination is earlier. The time when medullar cells stop differentiation for different body sites is more uniform compared with that for cortex cells. The variations of tip MAR among different body sites and individuals reveal various attrition rates of hair tips.