part_of part of part of contained in existence overlaps existence starts during or after produces material entity yolk cell tissue reproductive system juvenile stage vitelline gland yolk gland ISBN:9780070316607 Planarian_Anatomy https://orcid.org/0000-0003-2569-1939 | https://orcid.org/0000-0002-7535-4407 PMID:16344473 vitellaria PMID:16932928 https://doi.org/10.1101/279364 PMID:27163480 PMID:27149082 PMID:27501047 PMID:22074376 PMID:28072387 PMID:19247960 PMID:18942102 Glands surrounding the oviducts which produce yolk cells. Yolk cells deposited into the oviducts travel to the genital atrium where they are packaged, along with one or more zygotes, into developing egg capsules. PMID:17390146 PMID:23652002 vitellarium PMID:28434803 prepharyngeal region parapharyngeal region adult hermaphrodite copulatory region