Difference between revisions of "Sexual Differentiation - Anatomy & Physiology"
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* The foetus receives its genetic endowment in two equal portions from the male gamete ('''Spermatozoon''') and female gamete ('''Oocyte'''). | * The foetus receives its genetic endowment in two equal portions from the male gamete ('''Spermatozoon''') and female gamete ('''Oocyte'''). | ||
* The X sex chromosome is larger than the Y sex chromosome. | * The X sex chromosome is larger than the Y sex chromosome. | ||
| − | * '''Females''' have XX chromosomes. All oocytes contain one X chromosome, they are the '''homogametic''' sex. | + | * '''Females''' have '''XX''' chromosomes. All oocytes contain one X chromosome, they are the '''homogametic''' sex. |
| − | * '''Males''' have XY chromosomes. Spermatozoa form two distinct populations, one containing X chromosomes and one containing Y chromosomes. They are the '''heterogametic''' sex. | + | * '''Males''' have '''XY''' chromosomes. Spermatozoa form two distinct populations, one containing X chromosomes and one containing Y chromosomes. They are the '''heterogametic''' sex. |
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* The '''Y''' chromosome is required to '''initiate male development'''. | * The '''Y''' chromosome is required to '''initiate male development'''. | ||
* In absence of the Y chromosome, female gonads (Ovaries) will develop. | * In absence of the Y chromosome, female gonads (Ovaries) will develop. | ||
| − | * The prime male determining gene is '''SRY''' (sex determining region of the Y chromosome). SRY is a very small piece of DNA that acts as a molecular switch to regulate structural genes and autosomal chromosomes | + | * The prime male determining gene is '''SRY''' (sex determining region of the Y chromosome). * SRY is a very small piece of DNA that acts as a molecular switch to regulate structural genes and autosomal chromosomes, determining if and when they are to be activated. |
* The presence of SRY alone is sufficient to ensure development of male gonads (Testes). | * The presence of SRY alone is sufficient to ensure development of male gonads (Testes). | ||
| + | * Female is the default sex, in absence of SRY female gonads (Ovaries) will develop. | ||
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| + | |||
| + | * Subsequent gonadal development is dependent on a normal population of '''germ cells'''. | ||
== Internal Genetalia == | == Internal Genetalia == | ||
Revision as of 09:23, 3 July 2008
Genetic Sex
- Established at the time of fertilisation.
- The foetus receives its genetic endowment in two equal portions from the male gamete (Spermatozoon) and female gamete (Oocyte).
- The X sex chromosome is larger than the Y sex chromosome.
- Females have XX chromosomes. All oocytes contain one X chromosome, they are the homogametic sex.
- Males have XY chromosomes. Spermatozoa form two distinct populations, one containing X chromosomes and one containing Y chromosomes. They are the heterogametic sex.
- The Y chromosome is required to initiate male development.
- In absence of the Y chromosome, female gonads (Ovaries) will develop.
- The prime male determining gene is SRY (sex determining region of the Y chromosome). * SRY is a very small piece of DNA that acts as a molecular switch to regulate structural genes and autosomal chromosomes, determining if and when they are to be activated.
- The presence of SRY alone is sufficient to ensure development of male gonads (Testes).
- Female is the default sex, in absence of SRY female gonads (Ovaries) will develop.
- Subsequent gonadal development is dependent on a normal population of germ cells.