As in the female, the initial stages of development begin in the fifth week with development of the mesoderm forming the gonadal ridge.

 
  • 第4周,卵黃囊頂近尿囊處的內胚層出現稱(chēng)原始生殖細胞。第5周,生殖腺的體腔上皮細胞向深層增生成初級性索。
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