Sox9, a transcription factor, is essential for the development of multiple organs such as bone, testis, heart, lung, pancreas, intestine, and the nervous system [1]. It is involved in various molecular genetic pathways crucial for organ development, maintenance, and function. Mutations in the human SOX9 gene lead to campomelic dysplasia, often accompanied by 46, XY sex reversal [1]. Genetic models, like KO/CKO mouse models, have been instrumental in studying its functions.

In mouse gonadogenesis, Sox9 is detected in the male gonad at 11.5 days postcoitus. Germ-line knockout of Sox9 using a conditional null allele in mice shows that Sox9-/-mice die soon after 11.5 dpc due to cardiovascular defects. In vitro culture of XY Sox9-/-urogenital ridges results in gonads lacking testicular cords and Sertoli cell marker expression but with ovarian-specific marker expression, indicating Sox9 is essential for testis formation [2]. In pancreatic development, transgenic mouse models have dissected the role of Sox9, which is considered a master regulator. It maintains pancreatic progenitors, initiates endocrine differentiation, and maintains pancreatic ductal identity. It has also been linked to pancreatic cancer initiation [3].

In conclusion, Sox9 plays diverse and essential roles in organ development, including testis determination and pancreatic development. Studies using Sox9 KO/CKO mouse models have provided valuable insights into its functions in these processes and their associated diseases, such as campomelic dysplasia and pancreatic cancer.