| Background and aims: With the development of industrialization, there are various chemical compounds discharged into environment, some of which with estrogen-like activity can mimic the physiological and biochemical actions of endogenous estrogen or antagonize effects of androgen are defined as environmental estrogens. Currently, these materials have caused a growing concern about their deleterious effects on health of human and animals, such as reproductive dysfunction, abnormal development, some cancers and relative ecological effects. Polychlorinated biphenyls (PCBs) are a sort of environmental estrogen contaminants, including 209 different congeners, which are resistant to degradation in environment. Polychlorinated biphenyl congeners153 and 180 (PCB153 and PCB180), for example, their global environmental mean residence times are on the order of 110 and 70 years, respectively. According to the World Health Organization, PCBs are ubiquitous in environment and almost present in every part of ecosystem. They can accumulate and transfer in food chains. PCBs are of high lipophilicity and of high- accumulated toxicity to human and animals. PCBs can be detected in milk, serum and adipose tissue from human and wild animals. They can also pass through placentas and through human milk affecting the health of fetuses and babies. PCB153 level is the highest in three cardinal PCBs in adipose tissue of human, because it is persistent in environment and bodies and it is not easily degraded. In addition, PCB153 level is also the highest in PCBs in human milk. From the introduction above, we can see that there is a strong relation between PCB153 and human health. It was reported that PCBs had not only common properties of environmental estrogens, but also adverse effects on multisystem. In order to observe the effects of PCBs on embryonic development, we will employe the post-implantation whole mouse embryo culture technique. The period of neural tube closure of mouse embryos is at gestational day 8.5-9.75, which is also the critical period for central nervous system development, and during which rudiments of central nervous system and most of organs have formed and at the same time developmental embryos are susceptible to environmental factors. However, the study of effects of PCB153 on mouse embryonic development hasn't been reported during gestational day 8.5-9.75. So, we will conduct the experiment by using post-implantation whole embryo culture technique to confirm whether PCB153 has effects on growth and development and on central nervous system of mouse embryos. Based on this study, experimental data about embryonic teratogenesis by environmental pollutants will be collected; meanwhile, the whole embryo culture model of teratogenic effects of PCB153 on mouse embryos will be established, which will lay a foundation for later study on teratogenic mechanisms of PCB153; besides, effects of PCB153 on ultrastructures of visceral yolk sac (VYS) will be examined to confirm the relation between damaged ultrastructures of VYS and abnormal development of embryos.Methods: 1. Mouse embryos were explanted at gestational day 8.5 and were cultured in vitro for 28 hours in culture bottles containing rat serum with different doses of PCB153. Scores of embryonic growth and development from every group were statistically analyzed and then conclusions were drawn about effects of PCB153 on embryonic growth and development. Indices assayed included the endpoints of growth and development of embryos (VYS diameter, crown-rump length, head length, the number of somites ) and the endpoints of organ morphological differentiation of embryos (VYS circle, heart, neural tube closure, trunk turning, hindbrain, midbrain, forebrain, branchial arch, maxillary process, mandibular processs, anterior limb bud, posterior limb bud, auditory system, optical system and olfactory system.).2. Transmission electron microscopy (TEM) was used to examine ultrastructures of VYS cells from every group.Results: 1.There were no statistically significant differen...
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