Question

In human female the blastocyst

• A. Gets implanted in endometrium by trophoblast cells
• B. Forms placenta even before implantation
• C. Gets implanted into uterus 3 days after ovulation
• D. Gets nutrition from uterine endometrial secretion only after implantation

Answer 1

Answer: (A)

Gets implanted in endometrium by trophoblast cells

Answer 2

In human female, the blastocyte Gets implanted in endometrium by trophoblast cells. Following fertilization, a process known as cleavage occurs in which the cytoplasm of the zygote is evenly split among multiple smaller cells or morulas.

• A morula is reached in humans after the fourth day after fertilization.
• The blastula stage comes after the morula stage. The blastula is made up of blastomeres, which are organized in an inner cell mass and an outside layer termed trophoblast, respectively.
• The trophoblast cells implant the blastula in the uterine endometrial lining 7-9 days or around one week after ovulation.
• An embryo's sustenance is given by the nutrients released by the uterine cavity prior to implantation, such as iron and fat-soluble vitamins.
• Implantation in the endometrial uterine wall takes place at the blastocyst stage of embryonic development.
• Before implantation, the blastomeres of early blastocyst get arranged into an outer layer called trophoblast and an inner group of cells attached to the trophoblast called inner cell mass.
• It is the trophoblast layer through which the blastocyst gets attached to the endometrium and the inner cell mass gets differentiated as the embryo.

The release of the ovum, or female gamete, from the ovary, is known as ovulation. The isthmus region of the fallopian tube is where the male gamete, or sperm, and the female gamete, or fertilization, fuse. A zygote is created by this union. A multicellular fetus will develop inside the body of the mother from a diploid unicellular cell.

• After fertilisation, the zygote is separated.
• The zygote is changed into a morula through cleavage. It is distinguished by a dense clump of cells that contains 16–32 cells.
• A blastula stage or hollow mass of cells will result from this.
• The blastocoel, a hollow filled with fluid inside the cell ball, is encircled by an inner cell mass and trophoblast on the outside.
• The trophoblast layer expands into the uterine endometrial lining by dissolving endometrium molecules during about one week, or 7-9 days, following ovulation.
• This is followed by the gastrulation stage, during which the three germ layers—endoderm, mesoderm, and ectoderm—are formed through cell rearrangement.
• And this collection of cells is called a gastrula.
• The placenta develops after implantation.

Discover more from this chapter:Human Reproduction