An experimental study of trophoblast growth in the lung.

Trophoblast can be grown from blastocysts or ectoplacental cones of the mouse in a variety of extrauterine sites. An attempt was made to grow trophoblast in the lung under various conditions. In 94 mice, blastocysts, or cones, were introduced into the lung through the vascular system. Trophoblast growth never occurred. However, when blastocysts, or cones, were introduced directly into the lung, trophoblast grew in 30-50% of mice, depending on technique. Failure to grow from the intravascular position does not appear to be due to liberation of common products of ischemia because blastocysts produced normal trophoblast in the liver when implanted via the portal system, even in the presence of extensive necrosis. The inhibiting factor, which is apparently produced in the lung, is being investigated.