Regardless of sex, we all start off in the womb with a genital tubercle– a teeny equivocal nubble- between our legs. Then, around week 9 of gestation, this tiny arrangement turns into a penis or a clitoris depending on the various hormones we come across.
A new study, published in the open-access publication PLOS Biology, has further unraveled the whodunits of penis formation in the womb and the roles of different hormones involved. It turns out, it’s not quite as simple as scientists previously assumed.
One of the main “ingredients” is indispensable for penis development in the womb is testosterone, a hormone found that’s responsible for many of the physical characteristics specific to adult males, although it is also produced by women in smaller dosages. As a fetus, the testes pump out this hormone, which is then converted into 5a-dihydrotestosterone( DHT ), to cause the genital tubercle to develop into a penis not a clitoris.
However, just testosterone and the testes are not sufficient to close the deal. This new research demonstrating that penis development likewise relies on a few seconds process, called the “backdoor” pathway, which results in androsterone being converted into DHT as well, without the would be required for testosterone from the testes. Strangely enough, the enzymes needed for this pathway were found in the liver, the adrenal gland, and placenta. This suggests that the male genital tubercle can convert both testosterone and androsterone into DHT.
“Our develops demonstrate that masculinization of the male fetus depends not only on the testes, but also on other tissues, especially the placenta, ” Paul Fowler of the University of Aberdeen and Michelle Bellingham of the University of Glasgow in Scotland, said in a statement. “They likewise intimate explanations of vote for why ailments of placental shortage can lead to hypospadias and other abnormalities of growing of the male external genitalia.”
To reach these new revelations, the team drew blood tests from 42 male fetuses and 16 female fetuses between 11 and 21 weeks of pregnancy. During the gestation, they then tracked different levels of the various hormones and memo how genes were expressed in tissues.
They hope that a better understanding of this process could help prevent common birth defects that can affect the genitals. Writing about their research for The Conversation, Fowler and Bellingham explain that recent decades have recognized a massive rise in cases of hypospadias, a disorder affecting the development of the urethra. This rise has been attributed to the contaminants from plastics, such as phthalates, that are known to meddle with the work of hormones. Hopefully, if researchers have more knowledge about the hormonal pathways of genital change, it could be used to prevent such disorders.