2014 Group Project 4

2014 Student Projects
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The Group assessment for 2014 will be an online project on Fetal Development of a specific System. This page is an undergraduate science embryology student and may contain inaccuracies in either description or acknowledgements.

Genital

System Development

[NB: having formatting issues trying to put the following information into a table, an attempt at the table is included below]

• the initial stages of genital development are indifferent, both males and females are anatomically identical until morphological changes occur beginning at week 7
• males and female changes are determined by the chromosomal sexual differentiation which occurs at fertilisation
• initial stages of gonadal development begins during the fifth week of development. First change is a thickened area of mesothelium on the medial side of the mesonephros [primitive kidney]
• this proliferation + underlying mesenchyme produces a bulge known as the GONADAL RIDGE
• finger like epithelial chords [gonadal chords] grow into underlying mesenchyme
• This who structure is referred to as an indifferent gonad
• indifferent gonad consists of an external cortex and internal medulla
• in embryos with an XX sex chromosome, the cortex of the indifferent gonad progresses to developing into an ovary
• Conversely, embryos with an XY chromosome, the medulla of the indifferent gonad progresses into a testes
• CHROMOSOMAL SEX DETERMINATION - the indifferent gonads differ after the seventh week by the presence the SRY gene which produces the TESTES DTEREMINING FACTOR on the short arm of the Y Chromosome. Under this influence, the gonadal chords differentiate to somniferous cords expression of Sox9 and Fgf9
• once the gonad that develops [ovary or testes] then determines the type of sexual and genital differentiation which occurs
• fetal testes produce testosterone, dihydrotestosterone and anti mullerian hormone
• TESTES DEVELOPMENT -- insert picture here

- seminferous chords --> rete testes - development of dense tunica albiguinea- enlarging testes separate from the degenerating mesonephros to form the somniferous tubules, tubuli, recti and rate testis - seminferous tubules --> interstitial cells [leydig cells] which produce androgens - insert diagram showing the production of androgens (testosterone, dihydrotestosterone and antimullerian hormones (sertoli cells) )

• DEVELOPMENT OF OVARIES

- ovary not identifiable until 10th week - gonadal chords aren't prominent in developing ovary but extend to medulla and form the rate ovary OOGENESIS DIAGRAM

• DEVELOPMENT OF GENITAL DUCTS
• fifth and sixth weeks - mesonephric ducts (wolfing duct) and paramesonephric ducts (mullein ducts)