Development of the Reproductive System
© Dr Mark Hill (2011)
This section of notes covers genital development. Differences in development are dependent on a protein product of the Y chromosome SRY gene.
Mesonephric duct (Wolffian Duct) and paramesonephric (Müllerian Duct) contribute the majority of male and female internal genital tract respectively.
Human Male (stage 22)
The mesonephric/paramesonephric duct changes are one of the first male/female differences that occur in development, while external genitaila remain indeterminate in appearance for quite a while.
- Differentiation of gonad (Sex determination)
- Differentiation of internal genital organs
- Differentiation of external genital organs
The 2nd and 3rd stages dependent on endocrine gonad. Reproductive development has a long maturation timecourse, begining in the embryo and finishing in puberty. (More? Puberty)
Page Links: Introduction | Some Recent Findings | Reading | Development Overview |
Objectives | Learning activities | Computer Activities | Movies |
References | Glossary
Some Recent Findings
Yamada G, Suzuki K, Haraguchi R, Miyagawa S, Satoh Y, Kamimura M, Nakagata N, Kataoka H, Kuroiwa A, Chen Y.
Molecular genetic cascades for external genitalia formation: An emerging organogenesis program. Dev Dyn. 2006 Jul;235(7):1738-52.
"External genitalia are anatomical structures located at the posterior embryonic region as part of several urogenital/reproductive organs.
The embryonic anlage of the external genitalia, the genital tubercle (GT) develops as a bud-shaped structure with an initial urethral plate and later urethra. Embryonic external genitalia are considered to be one of the appendages.
Recent experiments suggest that essential regulatory genes possess similar functions for the outgrowth regulation of the GT and limb appendages."
Internal Genital Differentiation
Müllerian Duct (paramesonephric) - blue
Wolffian Duct (mesonephric) - red
- Human Embryology (2nd ed.) Larson Ch10 p261-306
- The Developing Human: Clinically Oriented Embryology (6th ed.) Moore and Persaud Ch13 p303-346
- Before We Are Born (5th ed.) Moore and Persaud Ch14 p289-326
- Essentials of Human Embryology, Larson Ch10 p173-205
- Human Embryology, Fitzgerald and Fitzgerald Ch21-22 p134-152
- Developmental Biology (6th ed.) Gilbert Ch14 Intermediate Mesoderm
- UNSW Embryology References
- Understand the role of the Y chromosome in sex determination.
- Understand the differences in male/female duct develpoment (mesonephric/paramesonephric).
- Compare the development of the cloaca in the male and female.
- Understand the developmental abnormalities in male and female development.
- Study the developmental overview of gonad/genital development.
- Study the early stage 13/14 embryo urogenital region and identify mesonephric duct, genital ridge.
- Study the late stage 22 male embryo urogenital region and identify mesonephric duct, paramesonephric duct, genital tubercle,
- Study the early female fetal (week 10) urogenital region and identify paramesonephric duct, mesonephric duct,
, ovary, developing uterus/vagina, genital tubercle.
- Watch the animations (listed under movies) of male/female genital development.
- Humans (week 5-6)
- Germ cells migrate into gonadal ridge
- Gonads (male/female) identical at this stage, indifferent
- dependent on sex chromosome
- Y testes
- No Y ovary
- SRY protein (Testes determining factor, TDF) binds DNA
- Transcription factor, Bends DNA 70-80 degrees
Internal Genital Organs
- All embryos form paired
- Mesonephric duct, see kidney development
- Paramesonephric duct, Humans 7th week
Invagination of coelomic epithelium
Cord grows and terminates on urogenital sinus
- Male Gonad (testes) secretes Mullerian duct inhibitory factor (MDIF) which causes regression of paramesonephric duct
- Male Gonad (testes) secretes Testosterone which retains mesonephric duct
External Genital Organs
- All embryos initially same (indifferent)
- Testosterone differentiates male
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