Except in the case of abstracted fiat boundaries such as the midline plane of an organism, all 2D anatomical entities have a 3 dimensional projection. For example, the surface of the shell of a muscle has a distinct shape that projects into the third dimension. Note that boundaries are 2D structures. They have no thickness - and so can not be sites of gene expression or gene product localisation. For this, use boundary region terms.

http://purl.obolibrary.org/obo/UBERON_0000015

Except in the case of abstracted fiat boundaries such as the midline plane of an organism, all 2D anatomical entities have a 3 dimensional projection. For example, the surface of the shell of a muscle has a distinct shape that projects into the third dimension. Note that boundaries are 2D structures. They have no thickness - and so can not be sites of gene expression or gene product localisation. For this, use boundary region terms.

non-material anatomical boundary

UBERON:0000015

non-material anatomical boundary

http://purl.obolibrary.org/obo/NCBITaxon_4751

http://purl.obolibrary.org/obo/NCBITaxon_33090

http://purl.obolibrary.org/obo/NCBITaxon_33208

http://purl.obolibrary.org/obo/UBERON_0000466