The nuclear receptor transcription factor Dax1 is hypothesized to play a role in testicular development, although the mechanism of its action is unknown. Here, we present evidence that Dax1 plays an early essential role in fetal testis development. We hypothesize that upregulation of Sox9 expression in precursor somatic cells, a process required for their differentiation as Sertoli cells, depends on the coordinated expression of Dax1, Sry and another gene, Tda1. Our conclusion and model are based on the following experimental findings: (1) presence of a mutant Dax1 allele (Dax1-) results in complete gonadal sex reversal in C57BL/6JEi (B6) XY mice, whereas testes develop in DBA/2J (D2) and(B6×D2)F1 XY mice; (2) B6-DAX1 sex reversal is inherited as a complex trait that includes the chromosome 4 gene Tda1; (3) B6 Dax1-/Y fetal gonads initiate development as ovaries, even though Sry expression is activated at the correct time and at appropriate levels; (4) upregulation of Sox9 does not occur in B6 Dax1-/Y fetal gonads in spite of apparently normal Sryexpression; and (5) overexpression of Sry in B6 Dax1-/Y fetal gonads upregulates Sox9 and corrects testis development.
Save the date - Human Development: Stem Cells, Models, Embryos
We will be hosting a 2026 Human Development: Stem Cells, Models, Embryos meeting. We have teamed up with the Wellcome-funded consortium, the Human Developmental Biology Initiative (HDBI) to co-organise this event, which will bring together researchers from around the world, united by an interest in understanding human developmental biology. Save the date for 7-9 September 2026 and register.
Development presents…
Development is delighted to host a webinar series showcasing the latest developmental biology and stem cell research. The webinars are held each month with talks from postdocs applying for independent positions as part of our Pathway to Independence programme. Visit Development presents... on the Node to see which stimulating topics are coming up in the next few months.
Meet our 2025 Pathway to Independence (PI) fellows
We are delighted to announce our third cohort of PI fellows - researchers whom we will be supporting as they transition from postdoc to Principal Investigator. Read about the eight talented fellows chosen, whom we're excited to be working with as they navigate the job market.
From bench to business
In this Perspective, researchers who have transitioned from academia to industry tell us how they have navigated patents, intellectual property, investors and biotechnology start-ups to bring new biological advances from the bench and into the boardroom.
Browse by subject
![Development logo - Browse by subject: Explore Development's content, now easily accessible by subject area. The ad has a black background with three vibrant scientific images: a developing embryo on the left, a green plant-like structure in the center, and a gastruloid (a circular cell with a bright pink center and blue outer ring) on the right. [Blue button: browse content].](https://cob.silverchair-cdn.com/ImageLibrary/Development/Snippets/2025_05_Dev_Browse-by-subject_600x230_Snippet.png?versionId=9135)
From cardiovascular development and regeneration to tissue engineering and organoids, Development’s browse by subject archive allows you to access the latest papers (from late 2024 onwards) on a particular field of interest. In addition to our curated subject collections, these subject pages allow readers to browse a broader range of papers organised by topic.
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