Where does “vitell-” come from?

vitell- (English) comes from Latin vitellus, from Latin -lus, from Proto-Italic -elos, from Proto-Indo-European -e-lós, from Proto-Indo-European -lós — Forms agent nouns from verbal roots.

Ancestry of “vitell-”, step by step

Step	Language	Word	Meaning
1	Latin	vitellus	a small calf; the yolk of an egg
2	Latin	-lus	Alternative form of -ulus; diminutive suffix
3	Proto-Italic	-elos	Forms desubstantival and deadjectival diminutive nouns
4	Proto-Indo-European	-e-lós	—
5	Proto-Indo-European	-lós	Forms agent nouns from verbal roots

Words derived from “vitell-”

vitellin
perivitellin
devitellinized
lipovitellin

Every word from Proto-Indo-European -lós →Every word from Latin -lus →Every word from Latin vitellus →