Priming carts, transfer trays, priming circuits, blood circuits, and related methods are disclosed. A transfer tray for receiving a neonate comprises a body and a movable support assembly. The body has a first portion to receive a neonatal chamber assembly with a neonate therein and a second portion to receive a blood circuit. The blood circuit includes an oxygenator, a first conduit for transfer of blood from the neonate to the oxygenator, and a second conduit for transfer of blood from the oxygenator to the neonate. The movable support assembly is affixed to the body of the tray and is configured to receive the blood circuit. When the neonate is disposed on the first portion and is in liquid communication with the blood circuit, the transfer tray is movable from a first position on a first surface to a second position on a second surface.