Both men and women produce estrogens as well as many other sex hormones. The difference is where these hormones produced. Estrogens are primarily produced in the ovaries and without having ovaries nobody will produce the estrogen blood levels significantly high enough to produce female characteristics. Everybody without ovaries will need external estrogens to develop and maintain female characteristics.
When a hormone is blocked or source removed, the other remaining hormones will tend to express themselves more. The actual pathways of hormone regulation in the body is very complex. Even if the primary source of estrogen is removed, there are other ways to produce estrogen, but not as effective as having your set of ovaries in working order.
