Consequently, in yuri media, "uke" and "seme" are, again, not really used.That particular dichotomy is not really even a thing in the Japanese conception of lesbianism, though other dichotomies, like "tachi"/"neko", are things.Using "uke" and "seme" for female-female relationships is weird and not generally done.For reasons that are unclear to me, these terms, unlike "uke" and "seme", do not seem to have percolated from the lesbian community to fans of yuri media. But, things like dic.pixiv and other websites for fans of yuri media generally do not use the terms "tachi" and "neko".The glossary on the website of the "Lesbian Girls Club" in Osaka (with the wonderful domain name "lesbian.jp") only uses "uke" and "seme" as part of comparisons to related notions specific to lesbianism, like "tachi" and "neko" (as noted in makihige's answer).
(dic.pixiv is obviously not a "reliable source" in the WP:IRS sense, but I'd say it is reflective of the views and concerns of the community of people who consume yuri media.) "HomuMado") having nothing to do with uke/seme.
On the other hand, in a relationship between two women, there is no need for one of them to "be the man" - and so the uke/seme distinction does not arise as obviously. Hence, we have this deep dichotomy between "uke" ("the woman") and "seme" ("the man"). Here is a basic (and oversimplified) sketch of how homosexuality is conceptualized: in a relationship between two men, one of them needs to "be the woman". I don't think Memor-X's answer quite gets at this. If you use "uke" and "seme" to describe particpants in yuri relationships, I imagine you'll be understood, but it'd be very weird - male homosexual relationships and female homosexual relationships are conceptualized quite differently from one another in Japan, and uke/seme is only an element of the former.