天气预报 > 育儿 > 胚胎是什么
胚胎是什么
更新时间: 2021-01-06 17:27:39  

1、囊胚、胚的早期发育和胚胎发育是一个连续过程。在体节时期,三个胚层都发生了变化。

2、外胚层在背部中线凹陷成沟,称神经沟,沟的两岸称神经脊。神经脊逐渐接近、愈合,致使神经演变为纵贯胚体的神经管。

3、神经管和神经脊将来演化为神经系统。内胚层随着胚体卷曲成管状,称原肠,原肠依部位又分为前肠、中肠和后肠。

关键词: 胚胎 什么

胚胎是什么相关经验

天气预报

最新推荐

页面:/news/view-1212831/ | 耗时:0.4921 s | 内存:2.11 MB | 查询:4 | 缓存读取:3 写入:0 | 加载文件:25
select * from tbl_Articles WHERE ArticleID=1212831 LIMIT 0,1
select * from tbl_Articles_data WHERE ArticleID=1212831 LIMIT 0,1
select * from tbl_Articles_sphinx where id=1212831 LIMIT 0,1
SELECT ArticleID,Title FROM tbl_Articles WHERE ArticleID IN(3469867,1938456,1643785,497754,1207477,1526539,475830,2414759,534720,1182183,3443858,3379659,3263759,597319,1996453,3091618,1635067,1173231,1329553,3499055,692874,1639521,767271,2671982,3506943,1008390,1052288,1018546,3326522,656781) ORDER BY field (ArticleID,3469867,1938456,1643785,497754,1207477,1526539,475830,2414759,534720,1182183,3443858,3379659,3263759,597319,1996453,3091618,1635067,1173231,1329553,3499055,692874,1639521,767271,2671982,3506943,1008390,1052288,1018546,3326522,656781)