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NYUCD GENERAL EMBRYOLOGY Exam 2026-2027 BANK
QUESTIONS WITH DETAILED VERIFIED ANSWERS EXAM
QUESTIONS WILL COME FROM HERE (100% Latest Already
Graded A+
Question 1
During the first week of development, the morula transforms into the
blastocyst. Which of the following events is essential for this
transformation?
A) Compaction mediated by E-cadherin
B) Formation of the primitive streak
C) Gastrulation
D) Neurulation
Answer: A
Explanation: Compaction is the process by which blastomeres maximize
their contact with each other, mediated by E-cadherin (a calcium-
dependent adhesion molecule). This compaction is essential for the
formation of the blastocyst, specifically the segregation of the inner cell
mass and the trophectoderm. The primitive streak, gastrulation, and
neurulation occur during the third week of development, not the first.
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Question 2
The inner cell mass of the blastocyst gives rise to which of the following
structures?
A) Trophoblast
B) Placental membranes only
C) The embryo proper, amnion, and yolk sac
D) Syncytiotrophoblast
Answer: C
Explanation: The inner cell mass (ICM) differentiates into the epiblast
and hypoblast, which together give rise to the embryo proper and the
extraembryonic membranes, including the amnion and yolk sac. The
trophoblast, including the syncytiotrophoblast, arises from the outer cell
mass, not the ICM.
Question 3
Implantation of the blastocyst into the endometrial lining normally
occurs at which stage of the endometrial cycle?
A) Proliferative phase
B) Menstrual phase
C) Secretory phase
D) Follicular phase
Answer: C
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Explanation: Implantation occurs during the secretory phase of the
endometrial cycle, specifically around days 20-24 of a 28-day cycle.
During this phase, the endometrium is prepared for implantation by
progesterone, which promotes glandular secretion and vascularization.
The proliferative phase is under estrogen control and precedes
ovulation.
Question 4
The primitive streak first appears at the beginning of the third week. Its
primary function is to:
A) Establish the dorsal-ventral axis
B) Form the notochord
C) Establish the craniocaudal axis and initiate gastrulation
D) Produce blood cells in the yolk sac
Answer: C
Explanation: The primitive streak establishes the craniocaudal (head-
tail) axis of the embryo and serves as the site through which epiblast
cells ingress to undergo epithelial-to-mesenchymal transition and form
the three germ layers during gastrulation. The notochord forms later as
a derivative of the node, and blood cell production is a function of the
yolk sac mesoderm.
Question 5
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The oropharyngeal membrane and the cloacal membrane are both
characterized by:
A) Being composed of all three germ layers
B) Being devoid of mesoderm and eventually rupturing
C) Giving rise to the neural tube
D) Forming the primitive streak
Answer: B
Explanation: Both the oropharyngeal membrane (at the cranial end)
and the cloacal membrane (at the caudal end) are bilaminar structures
consisting only of ectoderm and endoderm, with no intervening
mesoderm. They are the sites where the gut tube will eventually open to
the exterior. They eventually rupture to form the oral and anal
openings, respectively.
Question 6
The notochord develops from which of the following structures?
A) Primitive streak
B) Notochordal process from the primitive node
C) Paraxial mesoderm
D) Lateral plate mesoderm
Answer: B
NYUCD GENERAL EMBRYOLOGY Exam 2026-2027 BANK
QUESTIONS WITH DETAILED VERIFIED ANSWERS EXAM
QUESTIONS WILL COME FROM HERE (100% Latest Already
Graded A+
Question 1
During the first week of development, the morula transforms into the
blastocyst. Which of the following events is essential for this
transformation?
A) Compaction mediated by E-cadherin
B) Formation of the primitive streak
C) Gastrulation
D) Neurulation
Answer: A
Explanation: Compaction is the process by which blastomeres maximize
their contact with each other, mediated by E-cadherin (a calcium-
dependent adhesion molecule). This compaction is essential for the
formation of the blastocyst, specifically the segregation of the inner cell
mass and the trophectoderm. The primitive streak, gastrulation, and
neurulation occur during the third week of development, not the first.
,2|Page
Question 2
The inner cell mass of the blastocyst gives rise to which of the following
structures?
A) Trophoblast
B) Placental membranes only
C) The embryo proper, amnion, and yolk sac
D) Syncytiotrophoblast
Answer: C
Explanation: The inner cell mass (ICM) differentiates into the epiblast
and hypoblast, which together give rise to the embryo proper and the
extraembryonic membranes, including the amnion and yolk sac. The
trophoblast, including the syncytiotrophoblast, arises from the outer cell
mass, not the ICM.
Question 3
Implantation of the blastocyst into the endometrial lining normally
occurs at which stage of the endometrial cycle?
A) Proliferative phase
B) Menstrual phase
C) Secretory phase
D) Follicular phase
Answer: C
,3|Page
Explanation: Implantation occurs during the secretory phase of the
endometrial cycle, specifically around days 20-24 of a 28-day cycle.
During this phase, the endometrium is prepared for implantation by
progesterone, which promotes glandular secretion and vascularization.
The proliferative phase is under estrogen control and precedes
ovulation.
Question 4
The primitive streak first appears at the beginning of the third week. Its
primary function is to:
A) Establish the dorsal-ventral axis
B) Form the notochord
C) Establish the craniocaudal axis and initiate gastrulation
D) Produce blood cells in the yolk sac
Answer: C
Explanation: The primitive streak establishes the craniocaudal (head-
tail) axis of the embryo and serves as the site through which epiblast
cells ingress to undergo epithelial-to-mesenchymal transition and form
the three germ layers during gastrulation. The notochord forms later as
a derivative of the node, and blood cell production is a function of the
yolk sac mesoderm.
Question 5
, 4|Page
The oropharyngeal membrane and the cloacal membrane are both
characterized by:
A) Being composed of all three germ layers
B) Being devoid of mesoderm and eventually rupturing
C) Giving rise to the neural tube
D) Forming the primitive streak
Answer: B
Explanation: Both the oropharyngeal membrane (at the cranial end)
and the cloacal membrane (at the caudal end) are bilaminar structures
consisting only of ectoderm and endoderm, with no intervening
mesoderm. They are the sites where the gut tube will eventually open to
the exterior. They eventually rupture to form the oral and anal
openings, respectively.
Question 6
The notochord develops from which of the following structures?
A) Primitive streak
B) Notochordal process from the primitive node
C) Paraxial mesoderm
D) Lateral plate mesoderm
Answer: B
