Concerning medial and intimal thickening, the following is/are true:

a. Increase of wall mass is a consequence primarily of smooth muscle cell proliferation

b. Smooth muscle cells are normally quiescent at maturity

d. Heparin can suppress both proliferation and migration of smooth muscle cells

Endothelial proliferation does not contribute to an increase in wall mass which is secondary to smooth muscle cell proliferation. Smooth muscle cells are normally quiescent at maturity and their proliferation and migration are inhibited by heparin. Transplanting a vein into the arterial circuit causes some endothelial cell loss and smooth muscle cell proliferation.