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  • Dear gentlemen, SCIENCE has a confession.


  • Your life actually began as a female.


  • Well, phenotypically or physically speaking that is, though some prefer to call this stage gender neutral.


  • As you might know, when two people mate, they each combine half of their genetic information together; 23 chromosomes each.

    你或許知道,兩個人性交時會各自將一半的遺傳訊息合併在一起,也就是每人 23 個染色體。

  • One pair of these chromosomes helps to determine your sex.


  • If you're female, you contain two X chromosomes, one from your mother and one from your father, while males have one X and one Y chromosome.


  • At the moment of conception, you were of course male or female based on your genes but the Y chromosome doesn't kick in right away.


  • In fact, the first five to six weeks of embryonic development are attributed to the X chromosome alone, and females grow from embryo to fully developed to the influence of only the X chromosome.

    事實上,前 5、6 週胚胎的發育歸因於X染色體,而女性由胚胎到發育完全都只受到X染色體的影響。

  • So what does the Y chromosome do?


  • Once activated, one of the genes on the Y chromosome known as the SRY gene has two functions: to inhibit certain features of the X chromosome and to impose through dominance the physiological traits that a male must have.

    在Y染色體中的 SRY 基因一旦被活化,就會有以下兩種功能:抑制X染色體的某些特徵,以及控制並強加影響男性需要具備的生理特性。

  • The ovaries descend and become the testes, and the labia fuses to create the scrotum.


  • If you're a male, take a look.


  • Though it's more pronounced in some men than others, you'll likely notice a line or ridge of tissue on the scrotum, which is called the "scrotal raphe".


  • The skin of the scrotum and penis are zipped up like a zipper as the layers of cells develop in the embryo.


  • And the male variant of the clitoris?


  • Yep, that's the penis.


  • If the Y chromosome does not become activated for some reason, then the female phenotype or physical appearance will persist in a male.


  • Power added, this is also part of the reason males have nipples.


  • The nipples form before the activation of the Y chromosome and SRY gene and thus remain through development and life.

    在Y染色體和 SRY 基因被啟動前,乳頭就已經形成,並持續存在於往後的發育和人生中。

  • But, you don't develop breasts, sorry.


  • Got a burning question you want answered?


  • Ask it in the comments or on Facebook and Twitter and subscribe for more weekly SCIENCE videos.


Dear gentlemen, SCIENCE has a confession.


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