(来学网)中胚叶造血开始于()
  • A.
    (来学网)胚胎6周
  • B.
    (来学网)胚胎3周
  • C.
    (来学网)胚胎8周
  • D.
    (来学网)胚胎5周
  • E.
    (来学网)胚胎10周
正确答案:
B