BRS Embryology Study Guide Exam
with Actual Answers 2025-2026
Updated.
B - Answer 2. Which process establishes the three definitive germ layers? (A) Neurulation (B)
Gastrulation (C) Craniocaudal folding (D) Lateral folding (E) Angiogenesis
A - Answer The first indication of gastrulation in the embryo is (A) formation of the primitive
streak (B) formation of the notochord (C) formation of the neural tube (D) formation of
extraembryonic mesoderm (E) formation of tertiary chorionic villi
D - Answer Somites may differentiate into which of the following? (A) Urogenital ridge (B)
Kidneys (C) Notochord (D) Epimeric and hypomeric muscles (E) Epithelial lining of the GI tract
C - Answer Intermediate mesoderm gives rise to the (A) neural tube (B) heart (C) kidneys and
gonads (D) somites (E) notochord
E - Answer The developing embryo has a distinct human appearance by the end of (A) week
4 (B) week 5 (C) week 6 (D) week 7 (E) week 8
B - Answer The lateral mesoderm is divided into two distinct layers by the formation of the
(A) extraembryonic coelom (B) intraembryonic coelom (C) cardiogenic region (D) notochord (E)
yolk sac
A - Answer Very often the first indication that a woman has that she is pregnant is a missed
menstrual period. In which week of embryonic development does a woman experience her first
missed menstrual period? (A) Start of week 3 (B) Start of week 4 (C) Start of week 5 (D) Start of
week 8 (E) End of week 8
B - Answer A female newborn was found to have a large midline tumor in the lower sacral
area, which was diagnosed as a sacrococcygeal tumor. Which of the following courses of
treatment is recommended for this child? (A) Immediate chemotherapy and radiation treatment
(B) Surgical removal of the tumor by age 6 months (C) Surgical removal of the tumor at age 4-5
years (D) Surgical removal of the tumor at age 13-15 years (E) No treatment because this tumor
normally regresses with age
D - Answer A woman has her pregnancy suddenly terminated because of intrauterine fetal
death. At autopsy, the fetus shows severe pallor, generalized edema, and hepatosplenomegaly.
Which of the following would you suspect? (A) VATER (B) 13-Thalassemia minor (C) 13-
Thalassemia major (D) Hydrops fetalis (E) VACTER
,B - Answer The most common interventricular septal defect (VSD) seen clinically is (A)
persistent truncus arteriosus (B) membranous VSD (C) common ventricle (D) foramen secundum
defect (E) premature closure of foramen ovale
D - Answer Which of the following clinical signs would be most obvious on examination of a
patient with either tetralogy of Fallot or transposition of the great vessels? (A) Sweaty palms (B)
Lack of femoral artery pulse (C) Pulmonary hypertension (D) Cyanosis (E) Diffuse red rash
B - Answer Which of the following congenital cardiovascular malformations is most
commonly associated with maternal rubella infection? (A) Isolated dextrocardia (B) Patent
ductus arteriosus (C) Persistent truncus arteriosus (D) Coarctation of the aorta (E) Double aortic
arch
B - Answer The most common atrial septal defect (ASD) seen clinically is (A) common atrium
(B) foramen secundum defect (C) premature closure of the foramen ovate (D) persistent truncus
arteriosus (E) probe patency of the foramen ovale
E - Answer The ventral surface of the adult heart as seen on gross examination or
radiography is composed primarily of the (A) left atrium (B) left ventricle (C) inferior vena cava
(D) bulbus cordis (E) right ventricle
D - Answer The left recurrent laryngeal nerve recurs around the (A) left primary bronchus (B)
left subclavian artery (C) left subclavian vein (D) ductus arteriosus (E) left common carotid artery
C - Answer Which of the three primary germ layers forms the histologically definitive
endocardium of the adult heart? (A) Ectoderm (B) Endoderm (C) Mesoderm (D) Epiblast (E)
Hypoblast
E - Answer Which of the following is responsible for the proper alignment of the
atrioventricular canal and the conoventricular canal? (A) Lateral folding of the embryo (B)
Craniocaudal folding of the embryo (C) Programmed cell migration (D) Formation of the AP
septum (E) Dextral looping
D - Answer The hepatic sinusoids that can be observed histologically in an adult liver are
derived from the (A) supracardinal veins (B) anterior cardinal veins (C) posterior cardinal veins
(D) vitelline veins (E) subcardinal veins
A - Answer Which of the following arterial malformations is very common in premature
infants? (A) Patent ductus arteriosus (B) Coarctation of the aorta (C) Right aortic arch (D) Double
aortic arch (E) Abnormal origin of the right subclavian artery
, D - Answer A physician monitoring a newborn infant's heart sounds using a stethoscope
hears the characteristic murmur of a patent ductus arteriosus. How soon after birth should this
murmur normally disappear? (A) 1-2 months (B) 1-2 weeks (C) 1-2 days (D) 1-2 hours (E)
Immediately
E - Answer How soon after birth does the foramen ovale close? (A) 1-2 months (B) 1-2 weeks
(C) 1-2 days (D) 1-2 hours (E) Immediately
C - Answer A 9-year-old boy presents with complaints of numbness and tingling in both feet.
Examination reveals no pulse in the femoral artery, increased blood pressure in the arteries of
the upper extremity, and enlarged intercostal veins, Which of the following abnormalities would
be suspected? (A) Double aortic arch (B) Tetralogy of Fallot (C) Postductal coarctation of the
aorta (D) Right aortic arch (E) Abnormal origin of the right subclavian artery
E - Answer The coronary sinus is derived from which of the following? (A) Truncus arteriosus
(B) Bulbus cordis (C) Primitive ventricle (D) Primitive atrium (E) Sinus venosus
B - Answer The conus arteriosus is derived from which of the following? (A) Truncus
arteriosus (B) Bulbus cordis (C) Primitive ventricle (D) Primitive atrium (E) Sinus venosus
A - Answer The proximal part of the aorta is derived from which of the following? (A)
Truncus arteriosus (B) Bulbus cordis (C) Primitive ventricle (D) Primitive atrium (E) Sinus venosus
C - Answer The trabeculated part of the right ventricle is derived from which of the
following? (A) Truncus arteriosus (B) Bulbus cordis (C) Primitive ventricle (D) Primitive atrium (E)
Sinus venosus
C - Answer Tricuspid atresia is a cardiac malformation that involves which of the following
septa? (A) Aorticopulmonary septum (B) Atrial septum (C) Atrioventricular septum (D)
Interventricular septum
D - Answer A muscular VSD is a cardiac malformation that involves which of the following
septa? (A) Aorticopulmonary septum (B) Atrial septum (C) Atrioventricular septum (D)
Interventricular septum
A - Answer Tetralogy of Fallot is a cardiac malformation that involves which of the following
septa? (A) Aorticopulmonary septum (B) Atrial septum (C) Atrioventricular septum (D)
Interventricular septum
A - Answer D-Transposition of the great arteries is a cardiac malformation that involves
which of the following septa? (A) Aorticopulmonary septum (B) Atrial septum (C)
Atrioventricular septum (D) Interventricular septum
with Actual Answers 2025-2026
Updated.
B - Answer 2. Which process establishes the three definitive germ layers? (A) Neurulation (B)
Gastrulation (C) Craniocaudal folding (D) Lateral folding (E) Angiogenesis
A - Answer The first indication of gastrulation in the embryo is (A) formation of the primitive
streak (B) formation of the notochord (C) formation of the neural tube (D) formation of
extraembryonic mesoderm (E) formation of tertiary chorionic villi
D - Answer Somites may differentiate into which of the following? (A) Urogenital ridge (B)
Kidneys (C) Notochord (D) Epimeric and hypomeric muscles (E) Epithelial lining of the GI tract
C - Answer Intermediate mesoderm gives rise to the (A) neural tube (B) heart (C) kidneys and
gonads (D) somites (E) notochord
E - Answer The developing embryo has a distinct human appearance by the end of (A) week
4 (B) week 5 (C) week 6 (D) week 7 (E) week 8
B - Answer The lateral mesoderm is divided into two distinct layers by the formation of the
(A) extraembryonic coelom (B) intraembryonic coelom (C) cardiogenic region (D) notochord (E)
yolk sac
A - Answer Very often the first indication that a woman has that she is pregnant is a missed
menstrual period. In which week of embryonic development does a woman experience her first
missed menstrual period? (A) Start of week 3 (B) Start of week 4 (C) Start of week 5 (D) Start of
week 8 (E) End of week 8
B - Answer A female newborn was found to have a large midline tumor in the lower sacral
area, which was diagnosed as a sacrococcygeal tumor. Which of the following courses of
treatment is recommended for this child? (A) Immediate chemotherapy and radiation treatment
(B) Surgical removal of the tumor by age 6 months (C) Surgical removal of the tumor at age 4-5
years (D) Surgical removal of the tumor at age 13-15 years (E) No treatment because this tumor
normally regresses with age
D - Answer A woman has her pregnancy suddenly terminated because of intrauterine fetal
death. At autopsy, the fetus shows severe pallor, generalized edema, and hepatosplenomegaly.
Which of the following would you suspect? (A) VATER (B) 13-Thalassemia minor (C) 13-
Thalassemia major (D) Hydrops fetalis (E) VACTER
,B - Answer The most common interventricular septal defect (VSD) seen clinically is (A)
persistent truncus arteriosus (B) membranous VSD (C) common ventricle (D) foramen secundum
defect (E) premature closure of foramen ovale
D - Answer Which of the following clinical signs would be most obvious on examination of a
patient with either tetralogy of Fallot or transposition of the great vessels? (A) Sweaty palms (B)
Lack of femoral artery pulse (C) Pulmonary hypertension (D) Cyanosis (E) Diffuse red rash
B - Answer Which of the following congenital cardiovascular malformations is most
commonly associated with maternal rubella infection? (A) Isolated dextrocardia (B) Patent
ductus arteriosus (C) Persistent truncus arteriosus (D) Coarctation of the aorta (E) Double aortic
arch
B - Answer The most common atrial septal defect (ASD) seen clinically is (A) common atrium
(B) foramen secundum defect (C) premature closure of the foramen ovate (D) persistent truncus
arteriosus (E) probe patency of the foramen ovale
E - Answer The ventral surface of the adult heart as seen on gross examination or
radiography is composed primarily of the (A) left atrium (B) left ventricle (C) inferior vena cava
(D) bulbus cordis (E) right ventricle
D - Answer The left recurrent laryngeal nerve recurs around the (A) left primary bronchus (B)
left subclavian artery (C) left subclavian vein (D) ductus arteriosus (E) left common carotid artery
C - Answer Which of the three primary germ layers forms the histologically definitive
endocardium of the adult heart? (A) Ectoderm (B) Endoderm (C) Mesoderm (D) Epiblast (E)
Hypoblast
E - Answer Which of the following is responsible for the proper alignment of the
atrioventricular canal and the conoventricular canal? (A) Lateral folding of the embryo (B)
Craniocaudal folding of the embryo (C) Programmed cell migration (D) Formation of the AP
septum (E) Dextral looping
D - Answer The hepatic sinusoids that can be observed histologically in an adult liver are
derived from the (A) supracardinal veins (B) anterior cardinal veins (C) posterior cardinal veins
(D) vitelline veins (E) subcardinal veins
A - Answer Which of the following arterial malformations is very common in premature
infants? (A) Patent ductus arteriosus (B) Coarctation of the aorta (C) Right aortic arch (D) Double
aortic arch (E) Abnormal origin of the right subclavian artery
, D - Answer A physician monitoring a newborn infant's heart sounds using a stethoscope
hears the characteristic murmur of a patent ductus arteriosus. How soon after birth should this
murmur normally disappear? (A) 1-2 months (B) 1-2 weeks (C) 1-2 days (D) 1-2 hours (E)
Immediately
E - Answer How soon after birth does the foramen ovale close? (A) 1-2 months (B) 1-2 weeks
(C) 1-2 days (D) 1-2 hours (E) Immediately
C - Answer A 9-year-old boy presents with complaints of numbness and tingling in both feet.
Examination reveals no pulse in the femoral artery, increased blood pressure in the arteries of
the upper extremity, and enlarged intercostal veins, Which of the following abnormalities would
be suspected? (A) Double aortic arch (B) Tetralogy of Fallot (C) Postductal coarctation of the
aorta (D) Right aortic arch (E) Abnormal origin of the right subclavian artery
E - Answer The coronary sinus is derived from which of the following? (A) Truncus arteriosus
(B) Bulbus cordis (C) Primitive ventricle (D) Primitive atrium (E) Sinus venosus
B - Answer The conus arteriosus is derived from which of the following? (A) Truncus
arteriosus (B) Bulbus cordis (C) Primitive ventricle (D) Primitive atrium (E) Sinus venosus
A - Answer The proximal part of the aorta is derived from which of the following? (A)
Truncus arteriosus (B) Bulbus cordis (C) Primitive ventricle (D) Primitive atrium (E) Sinus venosus
C - Answer The trabeculated part of the right ventricle is derived from which of the
following? (A) Truncus arteriosus (B) Bulbus cordis (C) Primitive ventricle (D) Primitive atrium (E)
Sinus venosus
C - Answer Tricuspid atresia is a cardiac malformation that involves which of the following
septa? (A) Aorticopulmonary septum (B) Atrial septum (C) Atrioventricular septum (D)
Interventricular septum
D - Answer A muscular VSD is a cardiac malformation that involves which of the following
septa? (A) Aorticopulmonary septum (B) Atrial septum (C) Atrioventricular septum (D)
Interventricular septum
A - Answer Tetralogy of Fallot is a cardiac malformation that involves which of the following
septa? (A) Aorticopulmonary septum (B) Atrial septum (C) Atrioventricular septum (D)
Interventricular septum
A - Answer D-Transposition of the great arteries is a cardiac malformation that involves
which of the following septa? (A) Aorticopulmonary septum (B) Atrial septum (C)
Atrioventricular septum (D) Interventricular septum
