My personal opinion is that haematoxylin-eosin staining is a good method for assessing histological specimen characteristics. However, with regards to vascular tree cells, weigert and movat staining could be more useful. In addition, the functional characteristics of the artery coats may be well determined by histochemical methods.

I suggest Mason`s trichromic staining in order to contrast the specimen. With that, you can perform an analysis of diameter with Image J or Fiji. Its easier  with Mason because it allows more contrast among the different tissues.

Use histometric  or  morphometric  and the mentioned Programe above Image J