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Webster 1913 Edition

Adj.

(Anat.)

Situated under a zone, or zona; – applied to a membrane between the zona radiata and the umbilical vesicle in the mammal embryo.

subzonal ‎(not comparable)

Relating to a subzone.
(anatomy) Situated under a zone, or zona; applied to a membrane between the zona radiata and the umbilical vesicle in the mammal embryo.