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Science may have uncovered why humans only have one penis Snakes have two! 译文来源:龙腾网 HTTP://WWW.LTAAA.COM译文来源:龙腾网 HTTP://WWW.LTAAA.COM

科学或已探明为何人类只有一个丁丁,而蛇有俩!



Enlarge (Credit: Odin M. Eidskrem via Shutterstock/Salon)
Scientists may have uncovered why some animals, like snakes, have two penises, while humans and other mammals only have one. In a study published this week in Nature, researchers from Harvard Medical School looked at the differences between snake and reptile (squamates) genitals, and those of birds and mammals (amniotes).
In short they found that in reptiles genital growth mimics where legs sprout (or would sprout), and in mammals genitalia grows where a tail would develop.
All genitals originate from an embryonic structure called a cloaca. However, in reptiles and snakes, twin external genitals develop, while mammals only develop one. Scientists had yet to discover why this occurs, however they may have inched closer to an answer. From the Washington Post:
"According to this new research, the location of the cloaca might be the key. This embryonic trigger (which eventually turns into the urinary and gut tracks) sends out a molecular call to the cells around it. ‘Genitals,' it says, ‘make me some genitals.'
"Apparently in both locations, there are pools of cells that have the ability to receive this call from the cloaca," lead authorPatrick Tschopp told the Washington Post. "When you move the signaling center, you can recruit different cells."
Tschopp, who is a postdoctorate researcher in genetics at Harvard Medical School, is not sure why the cloaca cell pools are in different spots in these animals. The next step is to answer that question.译文来源:龙腾网 HTTP://WWW.LTAAA.COM
What Tschopp and his colleagues did find out is that when they moved the cloaca tissue next to growing limbs in chicken embryos, genitalia cells began to grow there.
This study is a fascinating look into how something, like cloaca and receptor cell location, could alter the evolution of a species. In the future, scientists hope to use this information to treat human medical conditions.

科学家或已探明为何一些动物,如蛇,有两个丁丁,而人类和其他哺乳类只有一个。本周,刊登于《自然》一个研究称,来自哈佛大学医学院的研究人员关注了蛇及爬行纲(有鳞目)动物的生殖器,同鸟类和哺乳类(羊膜生物)之间的差异。
简单地说,他们发现爬行类的生殖器从(将要)长腿的地方生长出来,而哺乳类的生殖器,从长尾巴的地方长出来。
所有的生殖器官都是从一个叫泄殖腔的胚胎组织分化而来。可是,在爬行类和蛇类中,存在双生的外生殖器,而哺乳类只长一个。科学家们尚未发现为何出现这种情况,然而,他们已十分接近答案。据《华盛顿邮报》:"根据这项新研究,泄殖腔的位置或是关键。该部位(它最终会发育成为泌尿系统和肠道)会向周围的细胞发射一个分子讯号‘生殖器'他说,‘给我造些生殖器。' "
"显然,这两个位置上,都有大量的细胞可以响应泄殖腔的讯号"研究论文的第一作者,帕特里克·特绍普告诉华盛顿邮报,"改变讯号中心的位置,你就能召集不同种类的细胞。"
哈佛大学医学院遗传学博士后,特绍普尚不确定,为何这几种动物的泄殖腔细胞池位置有所不同。下一步,就是要解答这个问题了。
特绍普和他的同事发现,当他们把泄殖腔组织移动到将要长出四肢的鸡胚胎上面的时候,生殖器官的细胞就开始在那里生长了。
这一研究的迷人之处在于,它发现了,如泄殖腔和受体细胞的位置,可以转变一个物种的进化情况。在未来,科学家希望把这一知识运用到人类医疗之中。