Marshall Valerie A, Carney Edward W
Toxicology and Environmental Research and Consulting, The Dow Chemical Company, Midland, MI, USA.
Methods Mol Biol. 2012;889:239-52. doi: 10.1007/978-1-61779-867-2_14.
Although the rabbit is used extensively in developmental toxicity testing, relatively little is known about the fundamental developmental biology of this species let alone mechanisms underlying developmental toxicity. This paucity of information about the rabbit is partly due to the historic lack of whole embryo culture (WEC) methods for the rabbit, which have only been made available fairly recently. In rabbit WEC, early somite stage embryos (gestation day 9) enclosed within an intact amnion and attached to the visceral yolk sac are dissected from maternal tissues and placed in culture for up to 48 h at approximately 37°C and are continuously exposed to an humidified gas atmosphere mixture in a rotating culture system. During this 48 h culture period, major phases of organogenesis can be studied including cardiac looping and segmentation, neural tube closure, and development of anlagen of the otic system, eyes and craniofacial structures, somites and early phases of limb development (up to bud stage), as well as expansion and closure of the visceral yolk sac around the embryo. Following completion of the culture period, embryos are evaluated based on several growth and development parameters and also are assessed for morphological abnormalities. The ability to sustain embryo development independent of the maternal system allows for exposure at precise development stages providing the opportunity study the direct action of a teratogen or one of its metabolites on the developing embryo. Rabbit WEC is perhaps most useful when used in conjunction with rodent WEC methods to investigate species-specific mechanisms of developmental toxicity.
尽管兔子在发育毒性测试中被广泛使用，但对于该物种的基础发育生物学，我们所知甚少，更不用说发育毒性的潜在机制了。关于兔子的信息匮乏，部分原因是历史上缺乏兔子的全胚胎培养（WEC）方法，而这种方法直到最近才得以应用。在兔子的WEC中，处于早期体节阶段（妊娠第9天）、被完整羊膜包裹且附着于内脏卵黄囊的胚胎，从母体组织中分离出来，置于约37°C的环境中培养长达48小时，并在旋转培养系统中持续暴露于湿润的气体氛围混合物中。在这48小时的培养期内，可以研究器官发生的主要阶段，包括心脏环化和分割、神经管闭合、耳系统、眼睛和颅面结构原基的发育、体节以及肢体发育的早期阶段（直至芽期），还有胚胎周围内脏卵黄囊的扩张和闭合。培养期结束后，根据几个生长和发育参数对胚胎进行评估，并对形态异常情况进行评估。独立于母体系统维持胚胎发育的能力，使得可以在精确的发育阶段进行暴露，从而有机会研究致畸剂或其代谢产物之一对发育中胚胎的直接作用。当与啮齿动物的WEC方法结合使用以研究发育毒性的物种特异性机制时，兔子的WEC可能最为有用。
