Somewehere on my Poser Storage HDD there is a texture callled VASCULAR (you may want to try a search in the FREE STUFF. You'd essentially need to make the veins, and save as a bump map. Try and search here. I'll check the terms and restrictions (if there is a readme) and send you the file if there is no problem. You can play from there.

"Few are agreeable in conversation, because each thinks more of what he intends to say than that of what others are saying, and listens no more when he himself has a chance to speak." - Francois de la Rochefoucauld

Intel Core i7 920, 24GB RAM, GeForce GTX 1050 4GB video, 6TB HDD space
Poser 12: Inches (Poser(PC) user since 1 and the floppies/manual to prove it!)