Sexual Differentiation Lesson

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Slide 1

Adventures in Biology

Last Week in….

We discussed the different forms of Reproduction

We discussed the costs/benefits of each form

This week we’ll discuss sexual

differentiation - how sexually reproducing organisms develop

into separate sexes. Specifically, as it applies to us humans

Slide 2

SO…How Do We Get From…

Here…

To here…

To here…

OR

?

(essentially a clump

of undifferentiated

cells)

(fully developed adult female)

(fully developed adult male)

Slide 3

In other words, How do our bodies know if we are meant to use the little boys’ room or the little girls’ room?

It’s the factor!

Slide 4

The Y chromosome contains a gene known as the SRY (sex determining region on the Y chromosome) gene.

This gene is responsible for the development of testes

But what about the factor?

Slide 5

Everyone develops an area known as the urogenital ridge

Unless testes develop, this area will naturally develop into the female reproductive system

In other words, we are all female by default

Slide 6

Slide 7

Slide 8

BUT…how does this happen??

When testes form they release 2 hormones - testosterone & MIS (mullerian inhibiting substance)

The testosterone causes the male reproductive system to develop

MIS causes the ducts of the female system to degenerate

Slide 9

Leads to

development

of mature male

reproductive

system

Slide 10

leads to the

natural

development

of the

Female reproductive organs

produces

Estrogen

& Progesterone

leads to

development

of mature

female

reproductive

system