Question

Blastocoel of embryo is

• A. Lysigenous cavity
• B. Schizogenous cavity
• C. True coelom
• D. None of the above

Answer 1

The correct option is B Schizogenous cavity

Around the fourth day after fertilization, cells of the pre-embryo continue to divide, but also begin to undergo differentiation and morphogenesis. During the next several days, cells present on the outside of the pre-embryo will begin to differentiate, or will begin to take on specific fates. In addition, cells of the pre-embryo will begin to make morphogenic movements, as the shape of the pre embryo changes from the mulberry shape of the morula to a more rounded ball-like shape. This ball of cells is called the blastocyst. If one were to cut this blastocyst, so that it could be observed in a cross section, three distinct regions would be observed. Inside the blastocyst, there is a hollow (schizogenous- formed by separation of cells) cavity, the blastocoel, as well as a collection of cells called the inner cell mass. The cell layer that makes up the outer sphere of the blastocyst is called the trophoblast. The cells of the trophoblast mediate the implantation of the blastocyst into the uterine wall of the mother. Implantation takes place during the second week of development.