Male-to-Female Transsexuals Have Female Neuron Numbers in a Limbic Nucleus (attend, experience)

[michel]

Original Studies

Male-to-Female Transsexuals Have Female Neuron Numbers in a Limbic Nucleus

Frank P. M. Kruijver, Jiang-Ning Zhou, Chris W. Pool, Michel A. Hofman, Louis J. G. Gooren and Dick F. Swaab
http://jcem.endojournals.org/cgi/con...ract/85/5/2034


Graduate School Neurosciences Amsterdam (F.P.M.K., J.-N.Z., C.W.P., M.A.H., D.F.S.), Netherlands Institute for Brain Research, 1105 AZ Amsterdam ZO, The Netherlands; Department of Endocrinology (L.J.G.G.), Free University Hospital, 1007 MB Amsterdam, The Netherlands; and Anhui Geriatric Institute (J.-N.Z.), The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, 230032 China

Address all correspondence and requests for reprints to: Frank P. M. Kruijver, M.D., or Prof. Dick F. Swaab, M.D., Ph.D., Graduate School Neurosciences Amsterdam, Netherlands Institute for Brain Research, Meibergdreef 33, 1105 AZ Amsterdam ZO, The Netherlands. E-mail: F.Kruijver@nih.knaw.nl.
An excerpt from:-


Transsexuals experience themselves as being of the opposite sex, despite having the biological characteristics of one sex. A crucial question resulting from a previous brain study in male-to-female transsexuals was whether the reported difference according to gender identity in the central part of the bed nucleus of the stria terminalis (BSTc) was based on a neuronal difference in the BSTc itself or just a reflection of a difference in vasoactive intestinal polypeptide innervation from the amygdala, which was used as a marker. Therefore, we determined in 42 subjects the number of somatostatin-expressing neurons in the BSTc in relation to sex, sexual orientation, gender identity, and past or present hormonal status. Regardless of sexual orientation, men had almost twice as many somatostatin neurons as women (P < 0.006). The number of neurons in the BSTc of male-to-female transsexuals was similar to that of the females (P = 0.83). In contrast, the neuron number of a female-to-male transsexual was found to be in the male range. Hormone treatment or sex hormone level variations in adulthood did not seem to have influenced BSTc neuron numbers. The present findings of somatostatin neuronal sex differences in the BSTc and its sex reversal in the transsexual brain clearly support the paradigm that in transsexuals sexual differentiation of the brain and genitals may go into opposite directions and point to a neurobiological basis of gender identity disorder.

[QTpi]

Thanks for posting the article, Michel. I knew it was some chemical or structural difference in the brain, but I didn't know exactly what. Now I do.

[michel]

Now that you have resurected that thread Qtpi, I have just realized that it is solely " Male-to-Female Transsexuals " which seems a bit strange............or am I being silly ? does that include Female to Male ?

[QTpi]

Originally Posted by michel

Now that you have resurected that thread Qtpi, I have just realized that it is solely " Male-to-Female Transsexuals " which seems a bit strange............or am I being silly ? does that include Female to Male ?

Argh!!! I just typed a long response and the forum ate it!!!!!!! I'll try to remember what I had typed.

Off the top of my head, I would think that it would be the same idea for both male-to-female and female-to-male transsexuals. They may not have done the research from that aspect yet. I do know that the genitals develop independently from the part of the brain controlling gender identity. The levels of certain hormones present in the mother's body during fetal development influences the brains's gender identity development. The brain is a fascinating thing to try to understand.

[michel]

Originally Posted by QTpi

Argh!!! I just typed a long response and the forum ate it!!!!!!! I'll try to remember what I had typed.

Off the top of my head, I would think that it would be the same idea for both male-to-female and female-to-male transsexuals. They may not have done the research from that aspect yet. I do know that the genitals develop independently from the part of the brain controlling gender identity. The levels of certain hormones present in the mother's body during fetal development influences the brains's gender identity development. The brain is a fascinating thing to try to understand.

That makes sense; Thanks.

[Shadow Wolf]

I remember watching a video from some high profile medical clinic (the do a "Holiday Seminar" every year, and students of what ever criteria are invited to attend) that said when chromosomes form in a newly convieved fetus, they twist, and in a male, if the chromosomes swap information just a nanometer off, an XY female is produced instead of a male. I thought maybe a type of information swap abnormality caused gender identity problems, but it looks as if I am wrong.

The brain is a fascinating thing to try to understand.

I will agree to that. Such as getting someone drunk with non-alcoholic drinks, or keeping them sober on alcoholic drinks.

The levels of certain hormones present in the mother's body during fetal development influences the brains's gender identity development.

Maybe the Surgeon general needs to warn that "pregnent women who consume drugs that produce high levels of estrogen risk causing gender identy problems with thier fetus if it is male."

[QTpi]

Originally Posted by Luke Wolf

I remember watching a video from some high profile medical clinic (the do a "Holiday Seminar" every year, and students of what ever criteria are invited to attend) that said when chromosomes form in a newly convieved fetus, they twist, and in a male, if the chromosomes swap information just a nanometer off, an XY female is produced instead of a male. I thought maybe a type of information swap abnormality caused gender identity problems, but it looks as if I am wrong.

You must be talking about the Howard Hughes Medical Institute Holiday Lecture Series. They are great! I use their material in my classes all the time. I think what you are referring to is the SRY factor, a section on the Y chromosome. Here is a description from HHMI that accompanies their Quick Time video:
Atypical male meiosis resulting in sex-reversed individuals

Meiosis begins just as in the previous example. However, this time the Y chromosome breaks below SRY, transferring SRY to the X chromosome. This produces two sperm with abnormal sex chromosomes. When they fertilize eggs, the XX (SRY+) embryo develops into a boy (top panel), and the XY (SRY–) embryo develops into a girl. They are sex reversed.