Male testes have many genes in common with female ovaries. In fact, even after the organs are fully developed, genes from the opposite sex can still be ‘switched on’. In amongst these blue and pink-coloured cells from a mouse testicle, sertoli cells (highlighted in greeny-yellow) help to make sperm. They also have active genes called Sox9 and Dmrt1, which keep the organ ‘male’ by preventing an ovary-forming gene called Foxl2 from switching on. In ovaries, there is a similar genetic puzzle, with Foxl2 working to stop ovary cells becoming more like testes. Using a genetically-modified mouse – allowing certain genes to be turned off – scientists can investigate this natural ‘genetic reprogramming’. Relationships between these genes may be crucial to understanding human sexual development, and even disorders later in life such as premature menopause.
Written by John Ankers
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