Before us is Mishnah 6 of chapter 8 of Yevamos, and it deals with three subjects: a saris chamah, an androginus and a tumtum, and their status with regard to Terumah, chalitzah and marriage.
A saris chamah kohen who married an Israelite woman:
The Mishnah opens: "Saris chamah kohen, shenasa bas Yisrael - ma'achilah biTerumah" - a kohen who is a saris chamah and who married an Israelite woman feeds her Terumah. A saris chamah is one who was sterile his whole life, that is, he was born that way. A kohen who is a saris chamah and who married an Israelite woman, that is, a woman who is not from a kohen's family, may feed her Terumah by virtue of the marriage, just like any kohen who marries an Israelite woman.
The reason is this: he is permitted to marry an Israelite woman, even though according to one opinion in the Mishnah a saris chamah is not subject to yibum, and neither is his wife. He is not considered a petzua daka or a kerus shafchah, for had that been the case he would have been forbidden to marry an Israelite woman, she would have become a zonah and would have been forbidden to a kohen, and she would not have been able to eat Terumah. But since she is permitted to him, he does feed her Terumah.
An androginus - the opinion of Rabbi Yosi and Rabbi Shimon:
"Rabbi Yosi v'Rabbi Shimon omrim" - Rabbi Yosi and Rabbi Shimon say. They raise the case of an androginus, a creature that has both male and female sexual organs together. In their view, an androginus who is a kohen "shenasa bas Yisrael - ma'achilah biTerumah" - who married an Israelite woman feeds her Terumah, for there is no prohibition whatsoever in this marriage and he is not forbidden to her.
More than that: it emerges from their words that an androginus is considered a definite male and not a female. For if he were a female, or even possibly a female, the betrothal would not take effect at all, and his wife would not be able to eat Terumah on his account.
However, the Gemara cites a beraisa in which Rabbi Yosi retracted this position and held that an androginus is a creature unto himself, and the Sages did not decide about him whether he is male or female. According to this conclusion, because of the doubt his wife would not be able to eat Terumah - unlike his position here in the Mishnah.
A tumtum who was opened up:
The Mishnah continues with the law of a tumtum, who is either a male or a female, except that his sexual organs are covered by a layer of skin, and only an examination by way of surgery will reveal whether he is male or female. In the words of the Mishnah: "Rabbi Yehudah omer: tumtum shenikra v'nimtza zachar - lo yachlotz, mipnei shehu k'saris" - Rabbi Yehudah says: a tumtum who was opened up and found to be a male does not perform chalitzah, because he is like a saris.
That is: a tumtum who was opened up, whether through surgery or on its own, and who was found to be a definite male, does not perform chalitzah, because his status is that of a saris. The Mishnah did not specify whether he is like a saris chamah or like a saris adam, but the commentators understood that since the matter came about through physical intervention, he is considered a saris adam. It turns out that Rabbi Yehudah follows the approach of Rabbi Eliezer, that a saris adam does not perform chalitzah and is not included in the section of yibum; whereas we perhaps follow Rabbi Akiva, that a saris adam does perform chalitzah.
"Nosei aval lo nisa":
The Mishnah rules regarding an androginus: "Nosei aval lo nisa" - he marries but he is not married. This line takes the position that an androginus is a definite male. "Nosei" - he fills the role of the male in marriage and can marry a woman. "Lo nisa" - he cannot enter marriage in the role of the woman, since according to this opinion he is a definite male.
The opinion of Rabbi Eliezer regarding relations with a male:
Rabbi Eliezer also agrees that an androginus is a definite male, but he comments on a different matter, relations with a male: "Androginus chayavim alav sekilah k'zachar" - for an androginus one is liable to stoning as for a male. One who has relations with an androginus in the manner of relations with a male is liable to death by stoning, which is the penalty for relations with a male, just as with any other male.
The Gemara notes, however, that this is said only when he had relations with him by way of the rectum, in the manner of relations between a male and an ordinary male; but if he had relations with him in the place considered to be his female organ, this is not the act of relations with a male about which the Mishnah is speaking. The liability applies only in the place where relations take place between a male and an ordinary male.
In summary: in this Mishnah we learned that a saris chamah kohen who married an Israelite woman feeds her Terumah, since he is not a petzua daka and she is not forbidden to him; that in the opinion of Rabbi Yosi and Rabbi Shimon an androginus kohen too feeds his wife Terumah, because he is a definite male - although Rabbi Yosi retracted in a beraisa and held that he is a creature unto himself, so that because of the doubt his wife does not eat; that in the opinion of Rabbi Yehudah a tumtum who was opened up and found to be a male does not perform chalitzah because he is like a saris; and that an androginus "marries but is not married," and in the opinion of Rabbi Eliezer one is liable to stoning for him as for a male.