I've never seen "adnate" before, but I can give some examples that seem to fit that definition:
1. The adrenal gland, which is moulded atop the kidney
2. The adrenal cortex which surrounds and has an entirely different function from the adrenal medulla
3. The pancreatic islet cells, which are embedded in
pancreas, but have entirely different function
Perhaps also parathryroids and the thyroid

A bit different:
adnexa
n.pl.
5ModL < L, neut. pl. of adnexus < adnectere: see ANNEX6 Anat. accessory parts or appendages of an organ !the ovaries are adnexa of the uterus"
ad[nex$al
adj.