mesocotyl, seedling mesocotyl, embryo mesocotyl

[planteome-user]

These anatomy terms, as defined, seem to be mesocotyl at different growth stages. If so, suggest keeping mesocotyl and dropping others. If not, the definitions should be expanded so that the differences, other than growth stage, are apparent.

Reported by: mlschaeffer

Original Ticket: obo/plant-ontology-po-term-requests/387