[Sex determination and sex differentiation]

Area of Science:

• Mammalian sexual development
• Molecular endocrinology
• Developmental biology

Context:

• Mammalian sex determination is a complex cascade involving chromosomes, gonads, and ducts.
• Testosterone induces male sex organ development, mediated by the cytoplasmic androgen receptor.
• The testicular feminization mutation (tfm) results in non-functional androgen receptors, leading to a female phenotype despite male gonads.

Purpose:

• To investigate the cellular mechanisms of sex determination in mammals, particularly the role of androgen receptors.
• To analyze the interaction between normal and androgen-insensitive cells in the development of genital ducts.
• To understand how cellular communication influences organogenesis in the context of hormonal signaling.

Summary:

• Experiments using mosaic mice and organ cultures of Tfm and normal tissues demonstrated that testosterone drives normal cells to express male functions.
• Androgen-insensitive Tfm cells differentiate along the female pathway.
• Crucially, both cell types communicate via local factors, influencing proliferation and organ structure, leading to the development of intersex organs rather than malformations.

Impact:

• This research elucidates the intricate interplay between cell-autonomous hormonal responses and non-autonomous cellular communication in mammalian sex determination.
• It provides insights into the development of intersex conditions and the potential for therapeutic interventions targeting cellular signaling pathways.
• The findings contribute to a deeper understanding of developmental biology and the genetic basis of sexual differentiation.