Thu Jan 09 00:00:00 UTC 2025: ## Study Reveals Crucial Role of Androgen Receptors in Chicken Sexual Development

**Kolkata, January 9, 2025** – New research from the Max Planck Institute of Biological Intelligence and Technical University, Munich, challenges established understanding of sexual development in birds. The study, published today, demonstrates that androgen receptors, traditionally associated with male development, are critical for both male and female fertility and sexual characteristics in chickens.

Researchers genetically modified chickens to lack androgen receptors. Both male and female birds lacking these receptors were infertile, exhibiting smaller gonads and delayed or absent bursal involution (shrinkage of a key lymphoid organ involved in sexual maturation). Furthermore, sex-specific behaviors, such as crowing in males and egg-laying in females, failed to develop, even with testosterone exposure. While some sex-linked physical traits persisted, their development was significantly impacted.

The study highlights the surprising breadth of androgen’s influence, affecting diverse tissues and contributing to the development of head ornaments (like combs) and ovarian follicles in females. This contrasts with the conventional view that androgens primarily affect male development, while estrogen and progesterone govern female development.

The findings suggest that avian sexual development is a complex interplay of hormone-dependent and -independent mechanisms. Certain traits, such as tail feather and spur length in males, remained unaffected by the lack of androgen receptors, indicating other contributing factors.

The researchers emphasize that these findings necessitate a reevaluation of the established understanding of avian sexual development and underscore the vital role of androgen receptors in both sexes. The study used CRISPR/Cas9 gene editing to successfully block androgen receptor function, providing reliable data supporting these significant conclusions. The research is expected to prompt further investigations into the intricacies of hormonal influence on sexual differentiation in birds and potentially other species.

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