How to visualize the ECM?
Different components of the ECM can be stained differently but since you asked about hyaluronic acid (HA) I'll limit my answer to its staining. 

See this paper. They use Hyaluran Binding Protein (HABP) as a specific probe for HA. 


  Because HA has a very simple, conserved composition and is
  ubiquitously expressed in all animals that have a developed immune
  response, HA is not immunogenic. Therefore, there are no antibodies
  that specifically recognize HA, and traditional immunohistochemical
  methods of detection of HA are not possible. Fortunately, a very
  specific and tightly binding protein, the hyaluronan binding protein
  (HABP), which is composed of the HA binding domain with the link
  module from aggrecan, was isolated (Hascall and Heinegård 1974;
  Tengblad 1979) and adapted as an HA probe (Ripellino et al. 1985).
  HABP is now widely employed for specific detection of HA.


Biotin tagged HABP can be used for IHC based visualization procedures.