> Nsg o-stems PBS *-as (3)> -uh > -Uneuter o-stems? I believe I've read that it is held to have come from
> Asg o-stems PBS *-am (2)> -uN > -U
> > 2. What is the origin of Common Slavic *-o the nom./acc. sg. of
>I don't get the whole idea of 'importation from pronouns'.
> NAsg n. o-stems PBS *-a[d] > -o. The endings *-om (o-stems)
> and *-os (s-stems) should have yielded -U, as indeed happens
> in many neuters (now masculines) which in PIE had the stress
> on the stem (e.g. *dhwórom > Slav. dvorU). Although stress
> plays no part in any of the other Auslautgesetze, there is a
> possibility that *-om became -uN while *-óm was still -áN,
> thus facilitating the shift to *-á (< *-ód) [after which
> surviving cases of *-áN became *-úN anyway?].