Assertion: placenta's structure | /r/HasProperty | eroded by the villi
Facets:
Source sentences:
text: Owing to their proteolytic action these villi destroy whatever tissue they come in contact with and of these the most important structures are the decidual blood vessels, which are eroded by the villi and hence the contained blood escapes between the villi so that in as early a specimen as the Bryce-Teacher or Peter’s ovum the primitive villi are seen to lie bathed in a pool of maternal blood.