part of embryonic organ development placenta blood vessel development labyrinthine layer development labyrinthine layer blood vessel development biological_process 2009-06-11T09:04:38Z dph GO:0060716 The process whose specific outcome is the progression of a blood vessel of the labyrinthine layer of the placenta over time, from its formation to the mature structure. The embryonic vessels grow through the layer to come in close contact with the maternal blood supply.