Explanation of relationship types

Three relationships and their reciprocal types are shown between anatomical structures.

Is part of and has part Structure B is a part of structure A during the time at which they both exist. Structure A may have a part B during the time at which they both exist.
   leaf is part of: tree
   tree has part: leaf, trunk, root

Has type and is a type of Structure B is a type of structure A. Structure A has subtypes B and C.
   parrot is a type of: bird
   bird has type: parrot, eagle, pigeon

Develops from and develops into Structure A develops from structure B. Structure B develops into structure A. There can be a one to one, one to many, or many to one correspondence. For example, Structure A develops from structure B and C, or structure A develops into structure B and C.
   cheese develops from: milk, bacteria
   milk develops into: cheese, yogurt, ice cream

These relationships are representations of formal types described by the OBO-REL ontology: http://www.bioontology.org/wiki/index.php/RO:Main_Page

Is part of and has part	Structure B is a part of structure A during the time at which they both exist. Structure A may have a part B during the time at which they both exist. leaf is part of: tree tree has part: leaf, trunk, root
Has type and is a type of	Structure B is a type of structure A. Structure A has subtypes B and C. parrot is a type of: bird bird has type: parrot, eagle, pigeon
Develops from and develops into	Structure A develops from structure B. Structure B develops into structure A. There can be a one to one, one to many, or many to one correspondence. For example, Structure A develops from structure B and C, or structure A develops into structure B and C. cheese develops from: milk, bacteria milk develops into: cheese, yogurt, ice cream