Human trophoblast cells were obtained from a term placenta and cultured through several stages. Using specific antibodies marked using an avidin biotin system and given the characteristic "invasiveness" of placental tissue, the Authors investigated the possible presence of those markers which have been found to be correlated with invasive and metastatic tumour cells. The positivity shown by cultured trophoblast cells towards laminin receptors and collagenase IV may have important implications which might explain the strange formation and maintenance of the human uteroplacental circulation in which embryonal tissue is in direct contact with maternal blood.