NYUCD GENERAL EMBRYOLOGY EXAM
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Question 1
During spermiogenesis, a deficiency in the function of the Golgi apparatus
would most directly impair the formation of which sperm structure?
A) Flagellum principal piece
B) Mitochondrial sheath
, C) Acrosome
D) Axial filament
Verified Answer: C) Acrosome
Explanation: The acrosome is a specialized lysosome-like organelle that
develops from the Golgi apparatus during spermiogenesis. It contains
hydrolytic enzymes crucial for penetrating the zona pellucida during
fertilization. Overlooking Golgi function directly leads to acrosomal defects
and subsequent infertility.
Question 2
At the moment of ovulation, a human oocyte is normal arrested at which
specific stage of cellular division?
A) Prophase of Meiosis I
B) Metaphase of Meiosis I
C) Prophase of Meiosis II
D) Metaphase of Meiosis II
Verified Answer: D) Metaphase of Meiosis II
Explanation: Primary oocytes arrest at prophase of meiosis I during fetal
development and remain there until puberty. Each month, LH surges induce
completion of meiosis I. The secondary oocyte then begins meiosis II but
arrests at metaphase II until a fertilizing sperm triggers completion.
Question 3
, A patient presents with a congenital defect characterized by a failure of cells to
migrate through the primitive streak. Which germ layers will be deficient or
completely absent?
A) Ectoderm and Endoderm
B) Mesoderm and Endoderm
C) Ectoderm and Mesoderm
D) Epiblast and Hypoblast
Verified Answer: B) Mesoderm and Endoderm
Explanation: Gastrulation is the defining process of the third week of
development. Epiblast cells undergo epithelial-to-mesenchymal transition and
migrate through the primitive streak. The initial wave replaces the hypoblast
to create definitive endoderm, while the subsequent wave spreads between the
layers to form the mesoderm.
Question 4
Which signaling molecule secreted by the notochord and prechordal plate is
primarily responsible for inducing the overlying ectoderm to differentiate into
the neural plate?
A) Sonic Hedgehog (Shh)
B) Bone Morphogenetic Protein 4 (BMP-4)
C) Fibroblast Growth Factor 8 (FGF-8)
D) Transforming Growth Factor Beta (TGF-β)
, Verified Answer: A) Sonic Hedgehog (Shh)
Explanation: The notochord acts as the primary organizer of the early embryo.
It secretes Sonic Hedgehog (Shh) along with BMP antagonists (such as
noggin and chordin). Shh establishes the ventral-dorsal patterning of the
neural tube and drives the differentiation of ectodermal tissue into neural
precursors.
Question 5
During a clinical evaluation, a newborn is diagnosed with an isolated cleft of the
secondary palate. This anomaly is caused by a failure of fusion between which
embryonic structures?
A) Medial nasal processes
B) Lateral nasal processes and maxillary processes
C) Palatine shelves of the maxillary processes
D) Median palatine process and lateral nasal processes
Verified Answer: C) Palatine shelves of the maxillary processes
Explanation: The secondary palate forms between embryonic weeks 8 and 12
from the internal palatine shelves of the maxillary processes. These shelves
must elevate above the tongue, grow horizontally toward the midline, and
fuse. Failure of this horizontal shelf fusion results in a cleft secondary palate.
Question 6
BANK | VERIFIED QUESTIONS &
DETAILED RATIONALES ULTIMATE
BUNDLE
Question 1
During spermiogenesis, a deficiency in the function of the Golgi apparatus
would most directly impair the formation of which sperm structure?
A) Flagellum principal piece
B) Mitochondrial sheath
, C) Acrosome
D) Axial filament
Verified Answer: C) Acrosome
Explanation: The acrosome is a specialized lysosome-like organelle that
develops from the Golgi apparatus during spermiogenesis. It contains
hydrolytic enzymes crucial for penetrating the zona pellucida during
fertilization. Overlooking Golgi function directly leads to acrosomal defects
and subsequent infertility.
Question 2
At the moment of ovulation, a human oocyte is normal arrested at which
specific stage of cellular division?
A) Prophase of Meiosis I
B) Metaphase of Meiosis I
C) Prophase of Meiosis II
D) Metaphase of Meiosis II
Verified Answer: D) Metaphase of Meiosis II
Explanation: Primary oocytes arrest at prophase of meiosis I during fetal
development and remain there until puberty. Each month, LH surges induce
completion of meiosis I. The secondary oocyte then begins meiosis II but
arrests at metaphase II until a fertilizing sperm triggers completion.
Question 3
, A patient presents with a congenital defect characterized by a failure of cells to
migrate through the primitive streak. Which germ layers will be deficient or
completely absent?
A) Ectoderm and Endoderm
B) Mesoderm and Endoderm
C) Ectoderm and Mesoderm
D) Epiblast and Hypoblast
Verified Answer: B) Mesoderm and Endoderm
Explanation: Gastrulation is the defining process of the third week of
development. Epiblast cells undergo epithelial-to-mesenchymal transition and
migrate through the primitive streak. The initial wave replaces the hypoblast
to create definitive endoderm, while the subsequent wave spreads between the
layers to form the mesoderm.
Question 4
Which signaling molecule secreted by the notochord and prechordal plate is
primarily responsible for inducing the overlying ectoderm to differentiate into
the neural plate?
A) Sonic Hedgehog (Shh)
B) Bone Morphogenetic Protein 4 (BMP-4)
C) Fibroblast Growth Factor 8 (FGF-8)
D) Transforming Growth Factor Beta (TGF-β)
, Verified Answer: A) Sonic Hedgehog (Shh)
Explanation: The notochord acts as the primary organizer of the early embryo.
It secretes Sonic Hedgehog (Shh) along with BMP antagonists (such as
noggin and chordin). Shh establishes the ventral-dorsal patterning of the
neural tube and drives the differentiation of ectodermal tissue into neural
precursors.
Question 5
During a clinical evaluation, a newborn is diagnosed with an isolated cleft of the
secondary palate. This anomaly is caused by a failure of fusion between which
embryonic structures?
A) Medial nasal processes
B) Lateral nasal processes and maxillary processes
C) Palatine shelves of the maxillary processes
D) Median palatine process and lateral nasal processes
Verified Answer: C) Palatine shelves of the maxillary processes
Explanation: The secondary palate forms between embryonic weeks 8 and 12
from the internal palatine shelves of the maxillary processes. These shelves
must elevate above the tongue, grow horizontally toward the midline, and
fuse. Failure of this horizontal shelf fusion results in a cleft secondary palate.
Question 6
