ie = also named as?

Context:
Introduction
Pig heart valves and tissues for orthopaedic (eg, for
ligament reconstruction) and general surgical (eg, small
intestinal submucosa for bladder repair) procedures
1
have been used in patients for decades. However, these
grafts have largely been structural tissues from which
the pig cells have been removed (panel 1); after trans-
plantation, the tissues are repopulated with human
recipient cells. Although these procedures represent a
form of xenotransplantation (ie, cross-species trans-
plantation), the main goal of research is to provide
viable pig organs and cells that will continue to function
after clinical transplantation.