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要了解胎儿在生长与发育过程中受到某种因素影响所造成的后果,必先熟悉胎儿的正常成长与发育要点。一、胚胎发育过程的三个时期胚前期(受精后第1周):由受精卵发育至胚泡形成。此时期胚胎对许多有害物质反应敏感,易受损伤;严重者可致死亡。但轻度损害并不影响其发育,主要由于新生的细胞多具有全能分化的潜力。胚期(第2～8周):为胚胎各系统形成阶段,易受致畸因素的影响;不少畸形即在此时期形成。
To understand the fetus in the process of growth and development by the impact of certain factors caused by the consequences, we must first familiar with the normal fetal growth and development points. First, the embryonic development of the three stages of preimplantation (1 week after fertilization): from fertilized eggs to blastocyst development. At this stage of the embryo sensitive to many harmful substances, vulnerable to injury; severe cases can cause death. However, mild damage does not affect its development, mainly due to newborn cells have more pluripotency potential. Embryonic stage (2 ~ 8 weeks): the embryo system formation stage, susceptible to the impact of teratogenic factors; many deformities that is formed at this time.