Which type of decidua covers the blastocyst?

The type of decidua that covers the blastocyst is known as the decidua capsularis. During the implantation process, the blastocyst embeds itself into the endometrium, which undergoes specific transformations to support pregnancy. The decidua is the modified endometrium that forms during pregnancy.

The decidua capsularis specifically refers to the tissue that directly envelops the implanted blastocyst, serving as a protective layer that contributes to the development of the placenta. As the pregnancy progresses, the decidua capsularis fuses with the decidua parietalis, which covers the rest of the uterine cavity. This fusion helps to create a smooth surface for the growing fetus and ensures that the placenta can effectively interface with maternal tissue.

Understanding the distinctions between the different types of decidua—decidua basalis, capsularis, parietalis, and decidua as a general term—is crucial in understanding early pregnancy and placental development, which are key concepts in obstetrics and gynecology.