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