Perspectives in Pediatric Pathology, Chapter 6. Male Undermasculinization

Area of Science:

• Developmental biology
• Endocrinology
• Genetics

Background:

• Normal male sexual development is a complex process.
• Requires coordinated action of fetal testicular hormones and target organ response.
• Deficiencies lead to male pseudohermaphroditism syndromes.

Purpose of the Study:

• To outline the essential mechanisms for normal male sexual differentiation.
• To describe the roles of anti-Müllerian hormone (AMH) and testosterone.
• To explain the contribution of 5-α-reductase in male development.

Main Methods:

• Review of established knowledge on male sexual development.
• Analysis of hormonal signaling pathways.
• Examination of genetic and enzymatic contributions.

Main Results:

• Normal male development requires fetal testis differentiation, hormone synthesis/secretion, and effective hormone action.
• Anti-Müllerian hormone (AMH) inhibits Müllerian duct development.
• Testosterone promotes Wolffian duct virilization, and its conversion to dihydrotestosterone by 5-α-reductase is crucial for external genitalia formation.

Conclusions:

• Disruptions in testicular differentiation, hormone production, or action result in disorders of sex development.
• Understanding these pathways is critical for diagnosing and managing male pseudohermaphroditism.
• The interplay of AMH, testosterone, and 5-α-reductase is fundamental to male virilization.