The Question is from neet-zoology human-reproduction pregnancy-and-embryonic-development, and it was created by the author A SUBRAMANYAM

Question

During human embryonic development, the inner cell mass differentiates into two layers: the epiblast and the hypoblast. Which of the following structures is NOT derived from the epiblast?

A SUBRAMANYAM · Accepted Answer

## CORE INFORMATION
✓ **Answer**: B
## CONCEPT FRAMEWORK
	**Primary Concept**: Early human embryogenesis and germ layer derivatives.
	**Related Topics**: Gastrulation, bilaminar disc, trilaminar disc, embryonic development
	**Prerequisites**: Understanding of the inner cell mass, epiblast, and hypoblast.
## SOLUTION PATHWAY
**Given Information**:
	The inner cell mass forms the epiblast and hypoblast.
	The question asks which structure is *not* derived from the epiblast.
**Method & Steps**:
	1. Recall the derivatives of the epiblast: The epiblast gives rise to all three primary germ layers: ectoderm, mesoderm, and endoderm. The amnion is also derived from the epiblast.
	Reasoning: During gastrulation, epiblast cells invaginate to form the primitive streak, which gives rise to the mesoderm and endoderm.  The remaining epiblast becomes the ectoderm. The amnion is formed from the amnioblasts, which are derived from the epiblast.
	2. Recall the derivatives of the hypoblast: The hypoblast primarily contributes to the formation of the yolk sac.
	Reasoning: The hypoblast is the ventral layer of the bilaminar disc and forms the lining of the yolk sac.
	3. Identify the structure not derived from the epiblast.
	Result: The yolk sac is derived from the hypoblast, not the epiblast.
	Verification: The other options (Amnion, Mesoderm, Ectoderm) are all known derivatives of the epiblast.
## OPTION ANALYSIS
[A] :x: Amnion: The amnion is derived from the epiblast.
[B] ✓: Yolk sac: The yolk sac is derived from the hypoblast, not the epiblast.
[C] :x: Mesoderm: The mesoderm is derived from the epiblast through gastrulation.
[D] :x: Ectoderm: The ectoderm is derived from the epiblast.
## LEARNING AIDS
	**Common Mistakes**:
		1. Confusing the derivatives of the epiblast and hypoblast:  It is crucial to understand the distinct roles of these two layers in early embryonic development.
		2. Overlooking the amnion's origin: Remember that the amnion, while a separate structure, originates from the epiblast.
	**Quick Tips**:
		1. Remember the acronym 'AME' for Amnion, Mesoderm, and Ectoderm, all derived from the epiblast.
		2. Visualize the bilaminar disc and the respective positions of the epiblast and hypoblast to better understand their derivatives.

A SUBRAMANYAM · Answer

Amnion

A SUBRAMANYAM · Answer

The correct Option is "Yolk sac"

A SUBRAMANYAM · Answer

Mesoderm

A SUBRAMANYAM · Answer

Ectoderm

NEET Zoology Human Reproduction Pregnancy And Embryonic Development MCQs

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