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Label the following diagram which illustrates the fertilization followed by cleavage and the early stages of embryonic development. Identify  and

a)

B-Ovary, E-Morula, F-Blastocyst, G-Cervix, H-Vagina

b)

B-Ovary, E- Blastocyst, F- Morula, G-Cervix, H-Vagina

c)

B-Ovary, E- Blastocyst, F- Morula, G- Vagina, H- Cervix

d)

B-Ovary, E- Blastocyst, F-Gastrula, G- Vagina, H- Cervix


Question ID - 7020 | Toppr Answer

Label the following diagram which illustrates the fertilization followed by cleavage and the early stages of embryonic development. Identify  and

a)

B-Ovary, E-Morula, F-Blastocyst, G-Cervix, H-Vagina

b)

B-Ovary, E- Blastocyst, F- Morula, G-Cervix, H-Vagina

c)

B-Ovary, E- Blastocyst, F- Morula, G- Vagina, H- Cervix

d)

B-Ovary, E- Blastocyst, F-Gastrula, G- Vagina, H- Cervix

1 Answer - 5876 Votes

3537

Answer Key : (b) -

(b)

Implantation

(i) Zygote divides rapidly by mitotic division. This is called cleavage. As a result 2, 4, 8, 16 daughter cells are produced which are termed as blastomeres

(ii) Embryo with 8-16 blastomeres is called a morula

(iii) The morula changes into a large mass of cells called blastocyst, which passes further into the uterus

(iv) Blastomeres in the blastocyst are arranged into an outer layer called trophoblast and an inner group of cells attached to trophoblast called inner cell mass

(v) The trophoblast layer gets attached to the cells of the endometrium and the inner cell mass gives rise to the embryo

(vi) The cells of endometrium divide rapidly and cover the blastocyst

(vii) So, the blastocyst gets embedded in the endometrium of the uterus. This is called implantation, which leads to pregnancy

Blastocyst Formation At the next stage of development (morula), which produces an embryo with about 64 cells, a cavity is formed with in the cell mass. This cavity is called blastocyst cavity (blastocoel) and the embryo is termed as blastocyst.

Blastocyst composed of an outer envelops of cells the trophoblast or trophoectoderm and inner mass cell (embryoblast). The side of the blastocyst to which inner mass cell is attached is called embryonic pole (animal pole), while opposite side is the abembryonic pole

The trophoblast encircles the blastocoel and inner mass cell. The inner mass cell is the precursor of the embryo. It means that inner mass give rise to embryo. The cells of the trophoblast helps to provide the nutrition to the embryo. The cells of the trophoblast form extra embryonic membranes namely chorion and amnion. The cells of the trophoblast which are in contact with inner mass are called cells of raubers



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