UNSW Embryology

Endocrine Development - Gonads

© Dr Mark Hill (2008)

Acknowledgements

Introduction

This page looks at gonad development in terms of endocrine function. Initial gonad differentiation is under the influence of testis-determining factor (TDF) fom the Y chromosome, which will then determine the support cells that will form and secrete the sex steroidal hormones. While gonad reproductive function is not acquired until pubery, the endocrine function of the gonad begins toward the end of the embryonic period when mesenchyme forming the interstitial cells (of Leydig) within the testes secrete testosterone, androstenedione.

Between the end of embryonic (8 weeks) to early fetal (12 weeks) hCG will also stimulate testosterone production. The Sustentacular cells also produce anti-mullerian hormone until puberty.

There are more specific notes on Genital Development

Some Recent Findings

Reading

• Human Embryology (2nd ed.) Larson
• The Developing Human: Clinically Oriented Embryology (6th ed.) Moore and Persaud Ch10: p230-233, Ch12: p280-282, Ch13: p319-347
• Before We Are Born (5th ed.) Moore and Persaud
• Essentials of Human Embryology Larson
• Human Embryology Fitzgerald and Fitzgerald Ch24: p166-167
• Search PubMed- Medline

Objectives

Learning activities

Computer Activities

UNSW Embryology:

Human Embryology Movies:

• Male Gonadal Development (434 Kb)
• Female Gonadal Development (315Kb)
• Male Genitalia Development (434 Kb)
• Descent of the Testes (221Kb)

Embryo Images Unit:

Embryo Images Online

• Urongenital Development
  • Internal Genitalia
  • External Genitalia

Video

Development Overview

Gonads (Covered in Sexual Differentiation) - Endocrine Gonad Notes

• Gonad- mesoderm (mesothelium and underlying mesenchyme) and primordial germ cells
• Gonadal ridge – mesothelium thickening, medial mesonephros
• Primordial Germ cells- yolk sac, to mesentery of hindgut, to genital ridge of developing kidney
• Gonad differentiation - dependent on presence (testes) or absence (ovaries) of expression of testis-determining factor (TDF) from Y chromosome
• Testis
• 8 Weeks – mesenchyme, interstitial cells (of Leydig) secrete testosterone, androstenedione
• 8 to 12 Weeks - hCG stimulates testosterone production
• Sustentacular cells- produce anti-mullerian hormone to puberty
• Ovary
• X chromosome genes regulate ovary development

Development Terms

Glossary of Terms

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