Date: March 2004
Have a question similar to the one I just read on this site.
Is it true that we are all "asexual" during the first stages of birth
until the intro of testosterone from the male gene?
We all start with primordial gonadal tissue which is neither testicular nor
ovarian and in the early stage iin utero have a phenotype (appearence) that
is more female than male. The trigger if you have a " male" chromosomal
compliment is the sry gene on the y chromosome, which will initiate mmale
development...resposiveness to androgens etc. If the sry gene is non
functional the phenotype is female but typically sterile. There are other
more complex genetic variances that result in phenotypic females with a y
chromosome. The lesson I tke is that the chromosomes do NOT deliniate the
sex and that what make one person a male or female is more in the mind's eye
and the soul than the body...the truth is stranger than fiction.
You are the sex you are genetically programmed to be at the moment of conception. It takes until about the 6th week of development, when the SRY gene on the Y chromosome turns on the male pattern of development, for the physical features (male phenotype) to begin to take shape. If there is no SRY, ie 2 X chromosomes, or if the SRY is mutated, the embryo develops as a female. SRY turns on a cascade of genes, and any one of those can also be mutated. For example, the gene for the production of testosterone can be mutated or the gene for the receptor of that protein can be mutated, and the male development is arrested at different points.
To answer your question, if you were to observe an embryo before this event happens, it would APPEAR to be asexual, but has already been determined what sex it will become.
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Update: June 2012