Eicher E M, Beamer W G, Washburn L L, Whitten W K
Cytogenet Cell Genet. 1980;28(1-2):104-15. doi: 10.1159/000131518.
A predictably high incidence of true hermaphroditism (3%) among fetal BALB/cWt mice provided the opportunity for studying the cause of inherited hermaphroditism. G-banded liver metaphase chromosomes were analyzed from 20 fetal hermaphrodites and from 15 normal female and male littermate controls. All hermaphrodites and seven males were chromosomal mosaics, i.e. XO/XY or XO/XY/XYY. In each mosaic fetus there were more XO than XYY cells. From these findings we hypothesize that BALB/cWt hermaphrodites arise from non-disjunction and probable loss of the Y-chromosome during mitosis. Results from breeding experiments indicated that a defect in the BALB/cWt Y-chromosome per se accounts for its nondisjunction and loss. A significant relationship was found between the amount of ovarian tissue and the percentage of XO cells in mosaic fetuses. If all chromosomally mosaic (XO/XY and XO/XY/XYY) individuals are considered, ovarian tissue was formed if there was 24% or more XO cells in an individual. If only hermaphroditic individuals are considered, ovarian tissue was formed if there were 44% or more XO cells. Finally, we found that the distribution of ovarian and testicular tissue within an ovotestis of BALB/cWt hermaphrodites was not random: ovarian tissue was situated at both ends or only at the cranial end; in only one case was ovarian tissue situated in the center flanked by testicular tissue. We suggest that such nonrandom distribution of ovarian and testicular tissue argues against the hypothesis that the organization of testicular tissue is dependent only on the presence of H-Y antigen.
在胎儿BALB/cWt小鼠中，真性两性畸形的发生率可预测地高（3%），这为研究遗传性两性畸形的原因提供了机会。对20只胎儿两性畸形小鼠以及15只正常雌性和雄性同窝对照小鼠的肝脏中期G带染色体进行了分析。所有两性畸形小鼠和7只雄性小鼠都是染色体嵌合体，即XO/XY或XO/XY/XYY。在每只嵌合体胎儿中，XO细胞比XYY细胞多。基于这些发现，我们推测BALB/cWt两性畸形小鼠是由有丝分裂过程中Y染色体的不分离和可能的丢失导致的。繁殖实验结果表明，BALB/cWt Y染色体本身的缺陷导致了其不分离和丢失。在嵌合体胎儿中，卵巢组织的量与XO细胞的百分比之间存在显著关系。如果考虑所有染色体嵌合体（XO/XY和XO/XY/XYY）个体，当个体中XO细胞占24%或更多时会形成卵巢组织。如果只考虑两性畸形个体，当XO细胞占44%或更多时会形成卵巢组织。最后，我们发现BALB/cWt两性畸形小鼠的卵睾内卵巢和睾丸组织的分布并非随机：卵巢组织位于两端或仅位于头端；仅在一个案例中，卵巢组织位于中间，两侧为睾丸组织。我们认为，卵巢和睾丸组织的这种非随机分布与睾丸组织的组织仅依赖于H-Y抗原存在的假说相悖。
