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Hermaphrodites are commonly seen in USMLE questions as they are a good example of pathology physiology clinical integration

Here's a short synopsis

Most importantly to remember
the default sex (when no hormones are secreted) is female.

During development if the following is secreted;

  1. Leydig cells ----- testosterone ----- internal male develop
  2. 5 alfa reductase action on testosterone -----dihydrotestosterone ---- external male develop
  3. Sertoli cells ------ Mullerian inhibitory factor ----- internal female prevented

If you don't have a testis such as in testicular dysgensis (for example Klinefilter) you don't have 1 so internal female by default and you also don't have 3 further favoring internal female. Of course if no 1 then no 2 which means no external male.

If you have 5 alfa reductase deficiency then 1 is there so internal male and 3 is there so no internal female but 2 is absent so no external male. They develop penis at 12 year old when more testosterone produced toward puberty.

Androgen insensitivity you have no androgen working on the cells so end up with the default sex (female) what's called testicular feminization syndrome.

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Still on TFS, they do not have pubic hair which is a function of testosterone which act on receptors in the hair follicles. They develop normal female breast because there is a lost of the inhibitory function of testosterone.
It defers from mullerian agenesis in that, In mullerian agenesis, there is also no development of female internal organs but there is the development of secondary sexual characteristics like breast, Pubic hair because the ovaries are functional, ie not part of the mullerian duct.
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