[Comparative ultrastructural study of freeze-etch replicas and thin sections of early human placenta]

Freeze-fracture replication was applied as a preparatory technique in the electron microscopic study of early human placenta. 6 placentas from 6 weeks to 11 weeks of pregnancy were studied in comparison with those prepared by the conventional thin section method. With the use of this technique, membranes were split by fracturing, disclosing two new fracture faces from the interior of the membranes and these new fracture faces are covered by numerous small particles on the smooth layer. Moreover, shadowing by Pt with a 45 degrees shadowing angle yielded a tridimentional image of organelles, such as the nucleus, secretion granules and others. Photographs of the freeze-fracture replication method were presented and discussion also referred to conventional TEM pictures of early human placenta.