Thompson R R, Adkins-Regan E
Department of Psychology, Cornell University, Ithaca, NY 14853.
Brain Res Dev Brain Res. 1992 Dec 18;70(2):231-7. doi: 10.1016/0165-3806(92)90202-8.
The nucleus preopticus medianus (POMn) is a sexually dimorphic nucleus in Japanese quail (Coturnix japonica) that is critically involved in the hormonal activation of male copulatory behavior. The larger volume apparent in males appears to depend upon circulating testosterone [Brain Res., 416 (1987) 59-68; J. Comp. Neurol., 303 (1991) 443-456]. The present study determined when during normal development this nucleus becomes dimorphic. POMn and a control nucleus, the nucleus commissurae pallii (nCPa), were traced from Nissl-stained coronal sections (40 microns) from animals sacrificed at 2, 3, 4, 5, 6 or 7 weeks of age. Areas were measured and used to calculate volume. POMn volumes were not significantly different in males and females through 5 weeks of age. The dimorphism in POMn volume then became apparent at 6 weeks of age as a function of an increase in male POMn volume between 5 and 6 weeks of age. No significant differences were apparent at any developmental age in nCPa volume. The appearance of a sexual dimorphism in POMn volume is coincident with the pubertal surge in testosterone that occurs between 5 and 6 weeks of age [Horm. Behav., 11 (1978) 175-182], and is also coincident with behavioral sexual maturity.
视前正中核（POMn）是日本鹌鹑（Coturnix japonica）中的一个两性异形核，它在雄性交配行为的激素激活过程中起着关键作用。雄性中明显较大的体积似乎取决于循环睾酮[《脑研究》，416（1987）59 - 68；《比较神经学杂志》，303（1991）443 - 456]。本研究确定了在正常发育过程中这个核何时变得具有两性异形。从2、3、4、5、6或7周龄处死动物的尼氏染色冠状切片（40微米）中追踪POMn和一个对照核，即 pallii 连合核（nCPa）。测量面积并用于计算体积。在5周龄之前，雄性和雌性的POMn体积没有显著差异。然后，POMn体积的两性异形在6周龄时变得明显，这是由于雄性POMn体积在5至6周龄之间增加所致。在任何发育年龄，nCPa体积都没有明显差异。POMn体积两性异形的出现与5至6周龄时发生的睾酮青春期激增[《激素与行为》，11（1978）175 - 182]同时出现，并且也与行为性成熟同时出现。
