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Common |
Female |
Male |
Internal Genital Tract Differentiation |
Müllerian Duct (paramesonephric) - blue |
Wolffian Duct (mesonephric) - 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 through the development of this system in time (and sex). Alternatively, both Internal and External Genitalia pages incorporate many movies which may help you understand the "dynamics" of changes in the embryo and fetus.
I have also included additional webpages and resources for some self-directed learning covering:
Link to next page in this Practical - Week 1 Sex Selection
Lets begin with the eariest events following fertilization.
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
Movie of Human Embryo Growth (this shows a human embryo growing, all images are to scale)
Movie of Mouse Embryo Growth (this shows a mouse embryo growing)