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Differentiation of the fetal gonad
1Department of Pediatrics, University of Helsinki, Finland.
Hormone Research
|January 1, 1992
Summary
Fetal gonadal differentiation involves distinct stages, with male development marked by Sertoli and Leydig cell appearance and hormone secretion. Hormonal regulation by pituitary and placental factors influences fetal sex development.
Area of Science:
- Developmental biology
- Endocrinology
- Reproductive medicine
Background:
- Gonadal differentiation progresses through pregonadal, indifferent, primary, and secondary sex differentiation stages.
- In males, Sertoli cells appear at 6-7 weeks and Leydig cells at 8 weeks, with testosterone peaking at 12-16 weeks.
- Ovarian differentiation occurs significantly later than testicular differentiation.
Purpose of the Study:
- To outline the stages of gonadal differentiation.
- To describe the timeline of key cellular and hormonal events in fetal sex development.
- To investigate the hormonal regulation of fetal gonads.
Main Methods:
- Review of developmental timelines for gonadal differentiation.
- Analysis of hormonal profiles during fetal development.
- Examination of the roles of fetal pituitary and placental hormones.
Main Results:
- Testosterone secretion peaks at 12-16 weeks, driving male secondary sex development and anti-Müllerian hormone production.
- Fetal testes synthesize and secrete inhibins.
- Lower luteinizing hormone (LH) and follicle stimulating hormone (FSH) in male fetuses suggest early pituitary responsiveness to gonadal hormones.
Conclusions:
- Fetal gonadal differentiation is a complex process with distinct temporal events for males and females.
- Hormonal feedback loops involving fetal pituitary and placental hormones (human chorionic gonadotrophin) are crucial for regulating fetal sex development.
- LH and FSH likely play regulatory roles in fetal gonadal function during late gestation.