Today's Daf Yomi is Yevamos 66
Rabbi Yaakov Culi (1685-1732) writes that it is debatable whether women are included in the prohibition of destroying seeds or not. He writes that according to Rabbeinu Tam, since women are not included in the comment of procreation, they are not forbidden to destroy human seeds, while according to Nachmanides, despite the fact that women are not commanded to procreate, they are still proscribed against destroying human seed. Amongst the medieval sages, there are two explanation of what exactly is the proscribed act of lesbianism. According to the Rivan, the forbidden act of lesbianism is when a woman emits the seed injected into her by husband in the context of intimate relations with another woman. According to another explanation cited in Tosafos, the act of lesbianism mentioned in the Talmud is the act of Tribadism. Rabbi Yosef Chaim of Baghdad (1835-1909) writes that even according to the first opinion, the prohibition of lesbianism is not because of the seed, which is spilled; rather, lesbianism is prohibited because of a separate prohibition banning all acts that are "Egyptian" in nature. The Mabit, Rabbi Moshe ben Yoseph di Trani the Elder (1505-1585), writes that while the prohibition banning "Egyptian acts" is biblical in origin while the prohibition of spilling one's seed is only possibly biblical, but not necessarily.
 Mishneh L'Melech to Laws of Forbidden Sexual Relations 21:18
 See Maimonides, Laws of Forbidden Sexual Relations 21:8
 Cited in Tosafos to Yevamos 66a
 To Yevamos 66a
 In his pseudonymous responsa Torah Lishmah §502, under the penname "Ezekiel the Blue"
 Kiryas Sefer to Maimonides' Laws of Forbidden Sexual Relations, Chapter 21
 Leviticus 18:3