Gingivae vs. Gingiva

These have not been consistently used in concepts representing plural and singular. If we say "Appearance of gingivae (observable entity)" is it necessarily plural and should it have a subtype of "Morphology of gingiva (observable entity)". Would this be singular?

This is my attempt at using the Discussions to note things that need to be looked at as we add or model content. We'll see how it works. :-)