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Common |
Female |
Male |
Internal Genital Tract Differentiation |
Paramesonephric Duct (Müllerian) - blue |
Mesonephric Duct(Wolffian) - red |
Aim:This practical is an introduction to the earliest events in Sexual Differentiation.
Key Concepts: Gonad, internal genitalia, external genitalia, ovary, testes, puberty, hormonal changes, gametogenesis, abnormalities.
Key Reading:
Key Online Resources:
Two key systems, neural and reproductive, develop over an extended period from the early embryo to puberty and the emerging adult. Interestingly, recent research is pointing to a link between these two systems in how male and female brains may differentially develop under the influence of sex hormones and perhaps even the sex chromosomes.
In understanding embryonic sexual development, think of a cascade of sequence dependent events that transform indifferent gonads, internal and external genitalia into distinct male and female structures. The process begins with gonad differentiation, which itself is tied developmentally back at the initial event of fertilization and the presence of either a Y or X chromosome in the sperm.
The endpoint of development could be considered the post-puberty active reproductive system. Though in these modern times, this too is regulated/delayed by our own neurological desire, or lack thereof, to reproduce.
The practical class is designed to work through a series of linked online resources with the help of a demonstrator and class tutors. The time to ask your questions is in the practical class with these experts available. All resources will remain permanently online, to allow future revision.
The Practical is a series of only 6 linked webpages that take you through an overview of the process of early sexual differentiation beginning with gonad development and subsequent internal and external genitalia development:
Work through the pages in sequence following the development of the urogenital system, considering both the time course and the dynamic events involved. A general timeline is shown below.
24 days - intermediate mesoderm, pronephros primordium
28 days - mesonephros and mesonephric duct
35 days - uteric bud, metanephros, urogenital ridge
42 days - cloacal divison, gonadal primordium (indifferent)
49 days - paramesonephric duct, gonadal differentiation
56 days - paramesonephric duct fusion (female)
100 days - primary follicles (ovary)
I have also included additional webpages and resources for some self-directed learning covering:
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Link to next page in this Practical - Week 1 Sex Selection Lets begin with the eariest events following fertilization.
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Use the alphabetical list below to find definitions of terms that are new to you or use the Google search window to search UNSW Embryology site.
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers |
Home Page
Embryo stages
Fetal Dev
Dev Notes 1
Dev Notes 2
System Notes
Acknowledgements
Practical Introduction
1. Sex Determination
2. Early Embryo
3. Late Embryo
4. Fetal
5. Postnatal
6. Abnormalities
Prac12 Male/Female Manual PDF
Male/Female Lecture
GIT Lecture
GIT Practical
Head Lecture
Head Practical
Endocrine Lecture
Male/Female Lecture
Male/Female Practical
BGD-B FAQs
Movies
News
Class Notes
Serial Images
K12 Students
Abnormal
Histology
Site Map
School of Med Sci
UNSW Medicine
University of NSW
UNSW Cell Biology
NCBI Books
Dev Biol (Gilbert)
This class is going to take you through the earliest steps in Sexual Differentiation using linked online resources you will use in the actual class.
Early sexual differentiation is closely linked to kidney development, therefore kidney development should be considered background reading.
Late sexual differentiation is closely linked to endocrine function, therefore endocrine development should be considered background reading.
The lefthand side menu has links to all pages (in sequence) required for this Lab, alternatively follow the white rabbit.... Also at the bottom of the same menu is a window to Search UNSW Embryology using any term/concept you do not understand. (note the search window uses Google, so will only work with an active internet connection.
If you are interested in a more detailed coverage, look at the Early Development 1 and Early Development 2 sections of Notes (from the lefthand menu).
These notes and linked materials have been prepared for Educational purposes only.Please email Dr Mark Hill if you wish to make a comment about this current project.
Beginnings, Growth and Development