Mammalian sexual differentiation: lessons from the spotted hyena

@article{Glickman2006MammalianSD,
  title={Mammalian sexual differentiation: lessons from the spotted hyena},
  author={Stephen E. Glickman and Gerald R. Cunha and Christine M. Drea and Alan J. Conley and Ned J. Place},
  journal={Trends in Endocrinology \& Metabolism},
  year={2006},
  volume={17},
  pages={349-356}
}

Figures from this paper

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References

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TLDR
This study suggests that androstenedione may also produce the profound virilization of female spotted hyenas.
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TLDR
The limited aromatase activity may allow the hyena placenta to convert high circulating concentrations of androstenedione to testosterone, which results in virilization of the fetal external genitalia and possibly destruction of fetal ovarian follicles.
Androgens and masculinization of genitalia in the spotted hyaena (Crocuta crocuta). 1. Urogenital morphology and placental androgen production during fetal life.
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TLDR
The hypothesis that external genital morphology is probably androgen-independent initially, but that fetal testicular androgens modify the secondary, male-specific phallic form and accessory organs is supported.
The marsupial model for male phenotypic development
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TLDR
It is demonstrated that the reproductive costs of clitoral delivery result from exposure of the female foetus to naturally circulating androgens, and the same androgens that render an extremely unusual and laborious process even more reproductively costly in the female are apparently essential to the male's physical ability to reproduce with a normally masculinized female.
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TLDR
It is shown that extensive somatic sexual dimorphisms precede by many days the first morphological evidence of testicular formation, which does not occur until around the third day of pouch life, and strongly suggest that some sexually dimorphic somatic characteristics develop autonomously, depending on their genotype rather than the hormonal environment to which they are exposed.
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