From: Miguel Carrasquer
>I was thinking:It should be added that Lith. has Abl. -> Gen. -õ in the pronouns (G.
>The original genitive (*-osyo) has been lost in the Slavic o-stems,
>replaced by the Ablative *-õ:d. The Ablative itself is a contraction
>of thematic vowel -o- + ending -od > -o:d. Suppose in monosyllabic
>pronouns such as *tU/*kU, *sI/*jI the uncontracted form survived into
>proto-Slavic as *too(d), *koo(d), *seo(d), *eo(d). We know that in
>the Anlaut, o- and u- receive a euphonic prefix *w- (v-) or *g(h)-
>(h-), basically to resolve a(n) hiatus with the preceding vowel (in
>Common Slavic, words ended in a vowel). The same hiatus blocker would
>have been inserted before o in the Ablative, giving *tovo, *kovo,
>*sevo, *jevo (as in std. Russian pronunciation) or *toho, *koho,
>*seho, *jeho (> togo, kogo, sego, jego).