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. Author manuscript; available in PMC: 2010 Nov 1.
Published in final edited form as: Future Neurol. 2010 Jan 1;5(1):47–59. doi: 10.2217/fnl.09.66

Figure 2. Model of how various factors result in sex differences in stroke phenotype.

Figure 2

An individual’s genetic inheritance determines biologic sex. The Sry gene is normally inherited on the Y chromosome. If Sry is present, the individual differentiates into a phenotypic male (XY) and develops testes. If Sry is absent, the individual differentiates into a phenotypic female (XX) and develops ovaries. Sex steroid hormones released by the testes (i.e., testosterone) and ovaries (i.e., estrogen and progesterone) subsequently trigger both organizational effects (irreversible changes) and activational effects (reversible effects dependent on the continued presence of the hormone). The sex chromosomes themselves may also trigger nongonadal effects and differential gene expression, further affecting phenotype. Prenatal environment and epigenetics can also influence phenotype. The combination of these factors results in sex differences in phenotype. Model based on concepts developed by AP Arnold [23,24].