vitellarium
From ZooTerms (Dictionary of Invertebrate Zoology)
yolk gland; a zone of growth.
vitellarium (noun; plural -ia; Latin vitellus, yolk; -arium, place for): 1. A
2. (Arthropoda: Insecta) That part of an ovariole that contains the developing eggs.
3. (Platyhelminthes) Glands which produce yolk material and possibly the eggshell.