temporal aspects of 'X development' terms

[J Clark]

Trying to clarify for own brain...

>> So for the above issue Doug has to ask himself, "Does an ichthyologist 
>> consider the vascular cord to be an is_a or part_of the vasculature?". 
>> If the answer is yes, then there is a relationship between it and 
>> vascular development, if the answer is no, then there is not.

This means:

Q1 Does an ichthyologist agree with either of these?

1)
[i]vasculature
---[p]vascular cord

or

2)
[i]vasculature
---[i]vascular cord

If yes, then there is a relationship between *something* and vascular 
development. What was the something?

(I also don't know much about kidney development which may not be 
helping. :-)

Thanks,

Jen