subzonal

Century Dictionary and Cyclopedia

1. Somewhat zonal or zonary, as the placenta of some mammals.
2. Lying below a zone, belt, or girdle: noting a membrane between the zona radiata and the umbilical vesicle of a mammalian embryo.

Wiktionary

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

GNU Webster's 1913

1. adj. (Anat.) Situated under a zone, or zona; -- applied to a membrane between the zona radiata and the umbilical vesicle in the mammal embryo.