Role of Androgen Receptors in Avian Sexual Development

January 10, 2025

Recent research from the Max Planck Institute of Biological Intelligence and Technical University, Munich, has revealed findings regarding androgen receptors in birds. Traditionally, androgens such as testosterone have been associated primarily with male sexual development. However, this study indicates that androgen receptors play important role in the sexual development and fertility of both male and female birds.

The Role of Androgen Receptors

Androgen receptors are essential for the sexual development of both male and female chickens. Research demonstrates that chickens lacking these receptors become infertile. Despite this infertility, both male and female chickens develop their respective gonads, albeit smaller than normal. This finding challenges the long-held belief that androgens are solely male hormones.

Effects on Sexual Behaviour and Traits

The absence of androgen receptors affects sexual behaviours and physical traits in both sexes. Female chickens without these receptors fail to develop and lay eggs, while males do not exhibit typical sexual behaviours. Certain physical characteristics, such as tail feathers and spurs, persist, but overall sexual traits are diminished.

Bursal Involution and Sexual Maturation

The bursa of Fabricius is a lymphoid organ in birds involved in immune response and sexual maturation. In chickens, this organ shrinks as they reach puberty. The study found that chickens without androgen receptors exhibited delayed or absent bursal involution, indicating disrupted sexual development. This process is sensitive to androgen activity.

Crowing Behaviour in Male Chickens

Crowing is a vital behaviour in male chickens, regulated by their internal body clock and influenced by androgens. Male chickens lacking androgen receptors do not crow, even when exposed to testosterone. This suggests that the development of neural circuits responsible for crowing is dependent on the presence of androgen receptors.

Comb Development and Sexual Maturity

Comb development is another indicator of sexual maturation in chickens. Male chickens without androgen receptors do not develop combs, even with testosterone exposure. In contrast, receptor-positive males begin to develop combs within 13 to 20 days after exposure to testosterone, denoting the importance of androgen receptors in this process.

The bursa of Fabricius aids in sexual maturation.
Male chickens without androgen receptors do not crow.
Comb development is androgen receptor-dependent.
Somatic cells in birds can show sexual traits independent of hormones.
Oestrogen receptors alone are insufficient for complete sexual maturation.

Hormonal Interactions in Sexual Development

This research puts stress on the complexity of hormonal interactions in avian sexual development. While androgens and oestrogens are crucial, their receptors dictate the overall sexual characteristics. The study marks that both hormonal and non-hormonal factors contribute to the sexual development of birds. About these interactions may lead to further vital information about avian biology and reproductive health.

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