MHT CET 202624 AprilEvening Shift
- Exam
- MHT CET
- Year
- 2026
- Date
- 24 April
- Shift
- Evening Shift
- Subject
- Biology
- Chapter
- Human Reproduction
MHT CET 2026 · 24 April · Evening Shift · Biology · Human Reproduction
During early embryonic development in humans, which of the...
During early embryonic development in humans, which of the following options shows the correct sequence of the various events given below.
I. Formation of hypoblast and epiblast
II. Appearance of primitive streak
III. Differentiation of cytotrophoblast and syncytiotrophoblast.
IV. Formation of amnion
I. Formation of hypoblast and epiblast
II. Appearance of primitive streak
III. Differentiation of cytotrophoblast and syncytiotrophoblast.
IV. Formation of amnion
Options
- AIII \rightarrow I \rightarrow IV \rightarrow II
- BII \rightarrow III \rightarrow IV \rightarrow I
- CI \rightarrow III \rightarrow II \rightarrow IV
- DIV \rightarrow I \rightarrow III \rightarrow II
Correct answer
A. III \rightarrow I \rightarrow IV \rightarrow II
Step-by-step solution
During early embryonic development, implantation starts around the 7th to 8th day. The trophoblast first differentiates into two layers: an inner cytotrophoblast and an outer syncytiotrophoblast (III).
Around the 8th day, the inner cell mass (embryoblast) differentiates into a bilaminar embryonic disc consisting of two layers: the hypoblast and the epiblast (I).
Following this, a small cavity appears within the epiblast, which enlarges to form the amniotic cavity. The epiblast cells adjacent to the cytotrophoblast differentiate into amnioblasts, which form the amnion (IV).
During the beginning of the third week of development (around day 14-15), gastrulation begins with the appearance of the primitive streak on the surface of the epiblast (II).
Thus, the correct sequence of events is III \rightarrow I \rightarrow IV \rightarrow II.
Answer: III \rightarrow I \rightarrow IV \rightarrow II
Around the 8th day, the inner cell mass (embryoblast) differentiates into a bilaminar embryonic disc consisting of two layers: the hypoblast and the epiblast (I).
Following this, a small cavity appears within the epiblast, which enlarges to form the amniotic cavity. The epiblast cells adjacent to the cytotrophoblast differentiate into amnioblasts, which form the amnion (IV).
During the beginning of the third week of development (around day 14-15), gastrulation begins with the appearance of the primitive streak on the surface of the epiblast (II).
Thus, the correct sequence of events is III \rightarrow I \rightarrow IV \rightarrow II.
Answer: III \rightarrow I \rightarrow IV \rightarrow II