Three for the Reference Library

One on Sex, one on Gender to start with.

The role of sexual related Y gene detection in the diagnosis of patients with gonadal dysgenesis by Yu et al, Chinese Medical Journal, 2001, Vol. 114 No. 2 : 128-131

Sixteen cases of gonadal dysgenesis were included in this study: 5 with androgen insensitivity syndrome, 1 with 17-α-hydroxylase deficiency, 4 with true hermaphrodite, 2 with 45,X/46,XY gonadal dysgenesis, 1 with 45,X gonadal dysgenesis, 1 with XY pure gonadal dysgenesis, 1 with testicular regression, and 1 XY female who gave birth to a normal baby.
...
Results Among the 16 cases, 15 were blood SRY positive, among which 13 (86.7%) showed the presence of testicular tissue, and 2 showed ovaries without testicular tissue . One SRY negative case showed the presence of testicular tissue. In 3 cases, SRY detection in gonadal tissue correlated with pathological findings but not with blood karyotype. The correlation between peripheral blood SRY and the pathology of the gonads was 81.25% and the correlation between the presence of peripheral blood Y chromosome and pathology of the gonads was 68.75%. Sequencing of the SRY motif in an XY female who gave birth to a normal baby showed no mutation.
Conclusions SRY detection is more sensitive and specific than blood karyotype in the prediction of the presence of testicular tissue. Peripheral blood karyotype does not necessarily reflect gonadal type. There may be testicular related factors other than the SRY gene.

So much for 46xy chromosomes indicating masculinity. Or even that karyotypes are definitive. Or even that presence of SrY stops a woman from giving birth. It's more complex than that.

Discordant Sexual Identity in Some Genetic Males with Cloacal Exstrophy Assigned to Female Sex at Birth by Reiner and Gearhart, N Engl J Med. 2004 January 22; 350(4): 333–341.

BACKGROUND Cloacal exstrophy is a rare, complex defect of the entire pelvis and its contents that occurs during embryogenesis and is associated with severe phallic inadequacy or phallic absence in genetic males. For about 25 years, neonatal assignment to female sex has been advocated for affected males to overcome the issue of phallic inadequacy, but data on outcome remain sparse.
METHODS We assessed all 16 genetic males in our cloacal-exstrophy clinic at the ages of 5 to 16 years. Fourteen underwent neonatal assignment to female sex socially, legally, and surgically; the parents of the remaining two refused to do so. Detailed questionnaires extensively evaluated the development of sexual role and identity, as defined by the subjects' persistent declarations of their sex.
RESULTS Eight of the 14 subjects assigned to female sex declared themselves male during the course of this study, whereas the 2 raised as males remained male. Subjects could be grouped according to their stated sexual identity. Five subjects were living as females; three were living with unclear sexual identity, although two of the three had declared themselves male; and eight were living as males, six of whom had reassigned themselves to male sex. All 16 subjects had moderate-to-marked interests and attitudes that were considered typical of males. Follow-up ranged from 34 to 98 months.
CONCLUSIONS Routine neonatal assignment of genetic males to female sex because of severe phallic inadequacy can result in unpredictable sexual identification. Clinical interventions in such children should be reexamined in the light of these findings.

Just a bit, yes. Because 8 of the 14 are boys, and only 5 are BiGendered or girls. And while Gender Role is mostly a social construct, some parts are not : All 16 subjects had moderate-to-marked interests and attitudes that were considered typical of males. Even though all but two had been raised as girls. This is similar to the results for 46xx people with CAH - 90% of whom have a female gender identity rather than a male one. Different parts of the brain have to be involved, and Gender Identity has a very imperfect correlation with Gender-typical behaviour.

One more thing:

A true hermaphrodite (case 4) had testicular tissue without the Y chromosome or the SRY gene.

Just to complicate matters.

My thanks once more to Professor Italiano for bringing these to my attention.

Now another, using fMRI:
Specific Cerebral Activation due to Visual Erotic Stimuli in Male-to-Female Transsexuals Compared with Male and Female Controls: An fMRI Study by Gizewski et al J Sex Med 2009;6:440–448.

ABSTRACT

Introduction. Transsexuals harbor the strong feeling of having been born to the wrong sex. There is a continuing controversial discussion of whether or not transsexualism has a biological representation. Differences between males and females in terms of functional imaging during erotic stimuli have been previously described, revealing gender-specific results.

Aim. Therefore, we postulated that male-to-female (MTF) transsexuals may show specific cerebral activation differing from their biological gender.

Main Outcome Measure. Cerebral activation patterns during viewing of erotic film excerpts in functional magnetic resonance imaging (fMRI).

Methods. Twelve male and 12 female heterosexual volunteers and 12 MTF transsexuals before any treatment viewed erotic film excerpts during fMRI. Additionally, subjective rating of sexual arousal was assessed. Statistics were performed using the Statistical Parametric Mapping software.

Results. Significantly enhanced activation for men compared with women was revealed in brain areas involved in erotic processing, i.e., the thalamus, the amygdala, and the orbitofrontal and insular cortex, whereas no specific activation for women was found. When comparing MTF transsexuals with male volunteers, activation patterns similar to female volunteers being compared with male volunteers were revealed. Sexual arousal was assessed using standard rating scales and did not differ significantly for the three groups.

Conclusions. We revealed a cerebral activation pattern in MTF transsexuals compared with male controls similar to female controls compared with male controls during viewing of erotic stimuli, indicating a tendency of female-like cerebral processing in transsexualism.

This is the formal writeup of the ArzteZeitung article I wrote about awhile ago.