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人类的生命是从卵子受精开始的。受精卵到第8周末,胚胎发育由单胚层、內、外二胚层、內、中、外三胚层到分化成为初具人形。8周末已可分辨出头、眼、耳、口、鼻和四肢的雏形,心脏的搏动已可用超声波查出。此时身长2.5cm,重量1克,脑重量占全身重量的25%。脑是全身各器官发育最早的一个。人脑发育最重要的阶段是从胎儿18周开始至生后2岁。这段时间里的关键时刻又是妊娠的最后3个月至生后6个月龄以內。因此,胎儿期,特别在妊娠后半期如果能进行合理的胎教,全有助于脑的发育和分化。
Human life begins with fertilization of the egg. Fertilized eggs by the end of the eighth week, embryonic development by the single embryo, inner and outer two germ, inner, middle and outer three germ layers to differentiate into a beginning of human form. 8 weeks have been able to distinguish the head, eyes, ears, mouth, nose and limbs of the prototype heart beat can be detected by ultrasound. Body length 2.5cm, weight 1 gram, brain weight accounted for 25% of body weight. The brain is the earliest body organ development. The most important stage of human brain development is from the fetus 18 weeks to 2 years after birth. The key moment in this period is again the last 3 months of pregnancy to less than 6 months of age after birth. Therefore, the fetus, especially in the second trimester of pregnancy if a reasonable prenatal care, all contribute to brain development and differentiation.