151 Yevamot 8/4-6

(4) Rabbi Yehoshua said: I have heard that a eunuch undergoes Chalitzah [the ceremony releasing the widow of a childless man from the obligation of Levirate marriage] and that one undergoes Chalitzah for his wife; and that a eunuch does not undergo Chalitzah and that one does not undergo Chalitzah for his wife, but I am unable to explain this. Rabbi Akiva said: I will explain it: a man-eunuch [castrated by a person] undergoes Chalitzah and one undergoes Chalitzah for his wife because there was a time when he was fit [to have children]; a sun-eunuch [who was born that way] does not undergo Chalitzah nor does one undergo Chalitzah for his wife since there was never a time when he was fit. Rabbi Eliezer says: Not so! Rather, a sun-eunuch undergoes Chalitzah and one undergoes Chalitzah for his wife because because there is a cure; a man-eunuch does not undergo Chalitzah nor does one undergo Chalitzah for his wife since he has no cure. Rabbi Yehoshua ben Betiera testified concerning Ben Megusat who was a man-eunuch in Jerusalem and they performed Yibum [Levirate marriage wherein a man weds his childless brother's widow] for his wife, to uphold the opinion of Rabbi Akiva.

(5) The eunuch neither undergoes Chalitzah nor performs Yibum. Similarly, an aiylonit [a woman with arrested sexual development who cannot bear children] neither performs Chalitzah nor undergoes Yibum. [If] a eunuch underwent Chalitzah from his Yevama [a woman whose husband died childless and whose brother-in-law must marry or dismiss her] he does not disqualify her [from subsequently marrying a priest]. If he had relations with her he does disqualify her since this is licentious relations [because she is forbidden to him]. Similarly, [if] brothers underwent Chalitzah from aiylonit they do not disqualify her [from marrying a priest]. If they had relations with her they do disqualify her since this is licentious relations.

(6) [If] a priest who was a sun-eunuch married the daughter of an Israelite, he confers upon her the right to eat Terumah [a portion of a crop given to a priest which becomes holy upon separation and may only be consumed by priests and their households]. Rabbi Yose and Rabbi Shimon said: [If] a priest who was an androginos [person with both male and female sexual organs. It is halachically uncertain whether such a person is male, female or, perhaps, has a uniquely defined halachic gender] married the daughter of an Israelite, he confers upon her the right to eat Terumah . Rabbi Yehudah said: [If] a tumtum [person with recessed sexual organs whose gender is therefore impossible to determine, presently, by external examination. It is halachically uncertain whether such a person is male or female] was torn and found to be male he may not undergo Chalitzah because he is like a eunuch. An androginosmay marry [a woman] but may not be married [to a man]. Rabbi Eliezer said: [If one has relations with] an androginos he is liable to be stoned like one [who has relations with] a male.