Seymoure P, Juraska J M
Department of Psychology, University of Illinois, Champaign 61820.
Brain Res Dev Brain Res. 1992 Oct 23;69(2):185-9. doi: 10.1016/0165-3806(92)90158-s.
The visual cortex of adult rats is sexually dimorphic at both the gross size and dendritic levels [Brain Res., 295 (1984) 27-34; J. Comp. Neurol., in press]. In addition, sex differences in the dendritic tree are dynamic and can be altered by environmental conditions imposed at weaning [Brain Res., 295 (1984) 27-34]. The present study examines sex differences in cortical thickness and in the dendritic tree of the monocular (Oc1M) and binocular (Oc1B) subfields in littermate male and female pairs of Long-Evans rats at weaning age (25 days). From Nissl-stained tissue, it was found that the whole cortex and layer II-IV of Oc1B was thicker in males than females. No sex differences were found in the thickness of Oc1M. Golgi-Cox-stained pyramidal neurons in layer III from the Oc1M and Oc1B regions were quantified in 7 littermate pairs of weaning-age rats. There were no sex differences in the basilar tree, while the apical oblique branches were sexually dimorphic, especially in the monocular region. Females had greater total dendritic length and longer terminal branches in Oc1M compared to males. Females also had longer bifurcating branches in both Oc1M and Oc1B than males. The present study found that sex differences at weaning age do not completely mirror the dimorphisms found in the visual cortex of the adult rat. This study also indicates that related subfields can differ in their morphology and should be examined separately.
成年大鼠的视觉皮层在总体大小和树突水平上都存在性别差异[《脑研究》，295 (1984) 27 - 34；《比较神经学杂志》，即将发表]。此外，树突的性别差异是动态的，并且可以通过断奶时施加的环境条件而改变[《脑研究》，295 (1984) 27 - 34]。本研究考察了断奶年龄（25天）的同窝雄性和雌性Long - Evans大鼠单眼（Oc1M）和双眼（Oc1B）子区域的皮质厚度以及树突的性别差异。从尼氏染色组织中发现，雄性的整个皮层以及Oc1B的第II - IV层比雌性厚。在Oc1M的厚度上未发现性别差异。对来自Oc1M和Oc1B区域的第III层经高尔基 - 考克斯染色的锥体神经元在7对断奶年龄的同窝大鼠中进行了定量分析。基底树突没有性别差异，而顶端斜支存在性别差异，尤其是在单眼区域。与雄性相比，雌性在Oc1M中的总树突长度更长，末端分支也更长。雌性在Oc1M和Oc1B中的分叉分支也比雄性长。本研究发现，断奶年龄的性别差异并不完全反映成年大鼠视觉皮层中发现的二态性。该研究还表明，相关子区域在形态上可能存在差异，应该分别进行检查。
