Given below are two statements.

Statement I: After implantation, chorionic villi are surrounded by the uterine tissue and maternal blood.

Statement II: The chorionic villi and uterine tissue become interdigitated with each other and jointly form placenta.

The trophoblast layer gets attached to the endometrium and the inner cell mass gets differentiated as the embryo. After attachment, the uterine cells divide rapidly and covers the blastocyst. As a result, the blastocyst becomes embedded in the endometrium of the uterus. This is called implantation and it leads to pregnancy.

After implantation, finger-like projections appear on the trophoblast called chorionic villi which are surrounded by the uterine tissue and maternal blood. The chorionic villi and uterine tissue become interdigitated with each other and jointly form a structural and functional unit between developing embryo (foetus) and maternal body called placenta.