Question:-
Describe the structure of blastocyst and blastulation.
Answer:-
(1) The term "trophoblast" or "trophoectoderm" refers to the outermost layer of morula cells. The nutritive fluid that is released by the uterine endometrial membrane is taken in by this layer.
(2) As more and more fluid is absorbed by trophoblast cells, The cells flatten out, creating a cavity known as the blastocyst cavity, blastocoel cavity, or segmentation cavity.
(3) This causes the trophoblast cells to separate from the endoplasmic reticulum
mass except on one side.
(4) The trophoblast cells in contact with the embryonal knob are known
as cells of Rauber. The morula rapidly expands and takes on the appearance of a cyst as the quantity of fluid increases. This stage is
called a blastocyst.
(5) The embryonic or animal pole is the side of the blastocyst to which the embryonal knob is attached, and the abembryonic pole is the opposite side.
(6)The trophoblast produces additional embryonic membranes and
Does not participate in the proper formation of the fetus.
(7) Zona pellucida disappears allowing the blastula to increase in
size and volume. The blastocyst stage is reached in about five
Days after insemination.
(8) The mother provides the blastocyst with the nutrition it needs through the placenta.
