Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, México City, Mexico. merchant @ servidor.unam.mx
Sex Dev. 2010;4(1-2):50-61. doi: 10.1159/000276768. Epub 2010 Jan 14.
In reptiles with temperature-dependent sexual determination, the thermosensitive period (TSP) is the interval in which the sex is defined during gonadal morphogenesis. One-shift experiments in a group of eggs define the onset and the end of the TSP as all and none responses, respectively. Timing for sex-undetermined (UG) and -determined gonads (DG) differs at male- (MPT) or female-producing temperatures (FPT). During the TSP a decreasing number of embryos respond to temperature shifts indicating that in this period embryos with both UG and DG exist. Although most UG correspond to undifferentiated gonads, some embryos extend UG after the onset of histological differentiation. Thus, temperature affects gonadal cells during the process of morphogenesis, but timing of commitment depends on individual embryos. A correlation between gonadal morphogenesis, TSP, and gene expression suggests that determination of the molecular pathways modulated by temperature in epithelial cells (surface epithelium and medullary cords) holds the key for a unifying hypothesis on temperature-dependent sex determination.
在温度依赖型性别决定的爬行动物中，热敏期（TSP）是在性腺形态发生过程中定义性别的时间段。一组卵中的单次移位实验分别将 TSP 的开始和结束定义为全有或全无反应。在雄性（MPT）或雌性产生温度（FPT）下，性别未决定（UG）和决定（DG）的性腺的时间不同。在 TSP 期间，对温度变化的反应数量减少，表明在此期间存在具有 UG 和 DG 的胚胎。尽管大多数 UG 对应于未分化的性腺，但一些胚胎在组织学分化开始后会延长 UG。因此，温度在形态发生过程中影响性腺细胞，但决定的时间取决于个体胚胎。性腺形态发生、TSP 和基因表达之间的相关性表明，温度对上皮细胞（表面上皮和髓质索）中调节的分子途径的决定是对温度依赖型性别决定的统一假设的关键。
