All-trans retinoic acid (ATRA), the biologically active form of vitamin A, is instrumental in regulating the patterning and specification of the vertebrate embryo. Various animal models demonstrate adverse developmental phenotypes following experimental retinoid depletion or excess during pregnancy. Windows of vulnerability for altered skeletal patterning coincide with early specification of the body plan (gastrulation) and regional specification of precursor cell populations forming the facial skeleton (cranial neural crest), vertebral column (somites), and limbs (lateral plate mesoderm) during early organogenesis. A common theme in physiological roles of ATRA signaling is mutual antagonism with FGF signaling. Consequences of genetic errors or environmental disruption of retinoid signaling include stage- and region-specific homeotic transformations to severe deficiencies for various skeletal elements. This review derives from an annex in Detailed Review Paper (DRP) of the OECD Test Guidelines Programme (Project 4.97) to support recommendations regarding assay development for the retinoid system and the use of resulting data in a regulatory context for developmental and reproductive toxicity (DART) testing.

全反式视黄酸 (ATRA) 是维生素 A 的生物活性形式，有助于调节脊椎动物胚胎的模式和规格。各种动物模型证明在怀孕期间实验性维甲酸消耗或过量后不利的发育表型。骨骼模式改变的脆弱性窗口与身体计划（原肠胚形成）的早期规范和早期形成面部骨骼（颅神经嵴）、脊柱（体节）和四肢（侧板中胚层）的前体细胞群的区域规范一致。器官发生。ATRA 信号的生理作用的一个共同主题是与 FGF 信号的相互拮抗。视黄醇信号传导的遗传错误或环境破坏的后果包括阶段和区域特异性同源异型转化为各种骨骼元件的严重缺陷。本评论来自经合组织测试指南计划（项目 4.97）的详细审查文件 (DRP) 中的附件，以支持有关类视黄醇系统的检测开发以及在发育和生殖毒性 (DART) 监管环境中使用结果数据的建议) 测试。