Question 1

A newborn male infant is examined. There is a palpable right testis, but no left testis, in the scrotal sac. The infant has no other abnormalities noted. Which of the following is the most likely abnormality involving the gonads of this infant?

A Agenesis

B Fusion

C Hypopituitarism

D Incomplete descent

E Leydig cell aplasia

F Venous atresia

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Question 2

Following ovulation and fertilization of an ovum, a blastocyst develops. Growth and differentiation occurs following implantation. Which of the following will develop into the placenta?

A Epimere

B Neural plate

C Sclerotome

D Trophoblast

E Yolk sac

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Question 3

A 5-year-old child fatigues easily. On examination a machinery-like murmur is auscultated over his chest. Echocardiography shows shunting of blood from the aorta to the pulmonary artery. An abnormality involving which of the following structures is most likely present in this boy?

A Ductus arteriosus

B Endocardial cushion

C Sinus venosus

D Third aortic arch

E Truncus arteriosus

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Question 4

A 3500 gm infant born at term is doing well and gaining weight normally until the fourth week of life. He then exhibits feeding difficulty with forceful vomiting. Now, on physical examination, no external anomalies are noted. However, there is a firm mass palpable in the upper mid abdominal region. Which of the following conditions is the infant most likely to have?

A Duodenal atresia

B Hepatoblastoma

C Hirschsprung disease

D Pyloric stenosis

E Tracheoesophageal fistula

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Question 5

An infant born at term is examined, and there is abnormal fusion of the 3rd, 4th, and 5th digits of the left hand. A radiograph of the left hand shows transformation of metacarpals I, II, III, and V to short, carpal-like bones. A mutation involving which of the following genes most likely led to these findings?

A CFTR

B FGFR3

C HOXD13

D SHH

E TBX5

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Question 6

An infant born at term has a radiograph taken. No congenital abnormalities are noted. The upper heart borders are not visualized. Which of the following structures is most likely to obscure the heart borders in this infant's radiograph?

A Esophagus

B Lymph node

C Stomach

D Thymus

E Vertebra

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Question 7

A secondary oocyte is developing normally. At which of the following times does the second maturation division of meiosis become completed?

A In the ovarian cortex

B During ovulation

C At fertilization

D In the blastocyst

E Upon implantation

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Question 8

During the 3rd week of embryonic development, splanchnic mesoderm differentiates into blood islands with angioblasts. In what developing tissue site does this process occur?

A Heart

B Liver

C Spleen

D Thymus

E Vertebra

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Question 9

An ovum is fertilized. After 3 weeks a blastocyst implanted on the endometrium has an inner embryoblast and an outer trophoblast. Which of the following is the next step in forming a 3-layered embryonic disk?

A Decidualization

B Gastrulation

C Lateralizaton

D Neurulation

E Placentation

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Question 10

A 55-year-old man has noted sharp pain in his right lower extremity for the past 2 months. MR imaging of his spine shows impingement on a spinal nerve root by a herniated structure located between L5 and S1. From which of the following embryonic derivatives does this herniated structure most likely arise?

A Amnion

B Cloaca

C Lateral plate mesoderm

D Neural crest

E Notochord

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Question 11

In the developing embryo, pharyngeal arches are formed. The second (branchial) arch gives rise to the stapedius, orbicularis oris, and posterior belly of the digastric muscles. Which of the following cranial nerves is also derived from this arch?

A III

B V

C VII

D IX

E XI

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Question 12

An infant born at 30 weeks gestation develops respiratory distress soon after birth. the infant is intubated and upon mechanical ventilation there are breath sounds auscultated over the right chest, but not over the left. An abnormality involving a derivative from which of the following embryonic structures is most likely present in this infant?

A Foregut

B Neural crest

C Somite

D Stomodeum

E Yolk sac

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Question 13

In the normally developing embryo, aortic arches are apparent by the end of the fourth week. Which of the following arteries is derived from the third pair of aortic arches?

A Carotid

B Pulmonary

C Stapedial

D Subclavian

E Umbilical

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Question 14

A 19-year-old primigravida gives birth at term following an uncomplicated pregnancy to a 3000 gm male infant. He has not passed any stool by day 2 of life. On physical examination his abdomen is distended. An ultrasound scan shows a dilated colon. Laboratory studies show a normal sweat chloride test. A mutation involving which of the following genes is most likely to be present in this infant?

A CFTR

B HFE

C KRAS

D RET

E P53

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Question 15

A fetus at 18 weeks gestation is normally formed and appropriately sized. No fetal or placental anomalies are present. Which of the following parts of the fetal vasculature is most likely to have the greatest oxygen concentration?

A Aorta

B Ductus arteriosus

C Pulmonary vein

D Right atrium

E Umbilical vein

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Question 16

An embryonic eye is developing normally. A retina is present on the posterior aspect of the globe. What is the embryologic origin of the portion of retina containing nerve cell bodies?

A Diencephalon

B Mesoderm

C Notochord

D Pharyngeal arch

E Surface ectoderm

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Question 17

A newborn examination is performed. The tympanic membranes are visualized bilaterally. What is the embryologic origin of the structure that forms the canal connecting the external ear to the tympanic membrane?

A Bony labyrinth

B First pharyngeal cleft

C Endolymphatic duct

D Otic pit

E Otic vesicle

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Question 18

A 2-year-old child has difficulty eating and drinking. On examination, there is a lateral cleft that involves the right upper lip. This defect is most likely due to failure in development and fusion of which of the following?

A Mandibular prominences and medial nasal prominences

B Mandibular prominences and secondary palate

C Maxillary prominences and mandibular prominences

D Maxillary prominences and secondary palate

E Medial nasal prominences and maxillary prominences

F Medial nasal prominences and secondary palate

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Question 19

A 20-year-old woman is unable to conceive and undergoes an infertility workup. A pelvic ultrasound reveals a bicornuate uterus. Which of the following is the most likely explanation for her anomalous uterus?

A Excess circulating maternal androgens while in utero

B Failure of primordial germ cell migration

C Failure of the paramesonephric ducts to fuse

D Failure of the urorectal septum to reach the perineum

E Low circulating levels of fetal estrogens

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Question 20

A newborn boy is noted to be dribbling urine. On examination he has a urethral opening on the ventral-midpoint of his penis. Abnormal development of which of the following structures is most likely responsible for his urinary problem?

A Anal pit

B Labioscrotal swellings

C Mesonephric ducts

D Prostatic urethra

E Urethral fold

F Urogenital sinus

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Question 21

In a developing embryo, neural crest cells form adjacent to the neural tube. These neural crest cells then undergo migration. Which of the following structures is derived from these migrating cells?

A Dorsal root ganglion

B Dura mater

C Epidermis covering the back

D Intervertebral disk

E Paravertebral muscle

F Sclerotomes

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Question 22

A newborn infant boy is noted to have an abnormality involving his perineum and scrotum. There is failure of midline fusion in the urogenital region. Chromosome analysis shows his karyotype is 46, XY. Which of the following is most likely responsible for his condition?

A Abnormal androgen levels in utero

B Failure of mesonephric ducts to reach the urogenital sinus

C Failure of the urorectal septum to reach the perineum

D Formation of a cloaca

E Persistence of the allantois

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Question 23

A neonate undergoes a check of health status. On examination a faint cardiac murmur is auscultated. Echocardiography is performed and shunting of blood is noted from the left atrium to the right atrium. An abnormality in embryonic development of which of the following structures has most likely occurred in this neonate?

A Ductus arteriosus

B Endocardial cushion

C Fourth aortic arch

D Sinus venosus

E Truncus arteriosus

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Question 24

The two superior and two inferior parathyroid glands are found adjacent to the posterior aspect of the thyroid gland. From which of the following are these parathyroid glands derived in embryologic development?

A Foramen cecum

B Mandibular swellings

C Maxillary processes

D Pharyngeal pouches

E Thyroglossal duct

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Question 25

A 29-year-old woman describes mild discomfort with sexual intercourse for the past month. A pelvic examination reveals no vaginal discharge, and the cervix appears normal. On examination she has a small, slightly tender 2 cm mass in the lateral wall of her vagina. The excised mass is cystic, fluid filled, and lined by a cuboidal epithelium. This mass is most likely to be a remnant of which embryologic structure?

A Allantois

B Labioscrotal swelling

C Mesonephric duct

D Urachus

E Urethral fold

F Urogenital sinus

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Question 26

An infant is noted to have respiratory distress soon after birth. Physical examination reveals no external anomalies. A chest radiograph shows a left lung mass. A CT scan shows a peripheral, posterior left lower lobe lung posteriorly, with both cystic and solid components. Thoracic surgery is performed and the left lower lobe is removed without difficulty. There are no adhesions or abnormal vascular connections. Which of the following conditions is most likely to produce these findings?

A Congenital pulmonary airway malformation

B Diaphragmatic hernia with pulmonary hypoplasia

C Extralobar pulmonary sequestration

D Kartagener syndrome

E Tracheoesophageal fistula with atresia

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Question 27

A 31-year-old woman has noted no fetal movement by 16 weeks gestation. A fetal ultrasound shows the fetal head contains a brain with thin cortex, single enlarged ventricle, and fused thalami. Which of the following developing regions of the brain is most likely abnormal in this fetus?

A Cranial vault

B Mesencephalon

C Prosencephalon

D Rhombencephalon

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Question 28

During normal embryonic development, anterior-posterior differentiation occurs. By the end of the fifth week, dorsomedial somitic cells give rise to myotomes forming the epimere. Which of the following muscles is most likely derived from these cells?

A Erector spinae

B Lateral pterygoid

C Latissimus dorsi

D Psoas major

E Sternocleidomastoid

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Question 29

In the developing embryo, limb buds form along an anterior-posterior axis as directed by a zone of polarizing activity (ZPA) in the mesenchyme. A product of which of the following genes is most important in signaling by the ZPA?

A Fibroblast growth factor 8

B Homeobox-B8

C Sonic hedgehog

D Transforming growth factor-beta

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Question 30

In the developing male embryo, primordial germ cells migrate and contribute to formation of gonads. These cells remain dormant until stimulated to differentiate. When do these primordial germ cells differentiate to spermatogonia?

A First trimester in utero

B Second trimester in utero

C Third trimester in utero

D Infancy

E Puberty

F 20 years of age

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Question 31

Following fertilization of the ovum, the ovarian corpus luteum continues to produce progesterone. If the corpus luteum regresses in the first trimester, abortion occurs. Which of the following hormones maintains this capability of the corpus luteum?

A Alpha-fetoprotein

B Estradiol

C Human chorionic gonadotropin

D Human placental lactogen

E Luteinizing hormone

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Question 32

A study is performed involving women exposed to rubella virus during pregnancy. Some of them give birth to infants with abnormalities including deafness, blindness, intellectual disability, and seizure disorder. At what point in gestation is exposure to this virus most likely to be associated with appearance of these complications?

A 4 weeks

B 12 weeks

C 20 weeks

D 28 weeks

E 36 weeks

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Question 33

Following coitus, spermatozoa migrate to the fallopian tubes. Within the tubes, the acrosomal head of spermatozoa undergoes reduction of glycoprotein coating with increasing permeability to calcium. Which of the following functions of spermatozoa is facilitated by this process?

A Blocking other sperm

B Fertilization

C Motility

D Mitosis

E Meiosis

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Question 34

A 22-year-old woman has noted no fetal movement at 17 weeks gestation. A screening fetal ultrasound shows a midline abdominal wall defect, with bowel contents contained within a membranous sac. Her serum alpha-fetoprotein is increased. Which of the following abnormalities is most likely present in her fetus?

A Exstrophy

B Gastroschisis

C Omphalocele

D Patent urachus

E Persistent vitelline duct

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Question 35

During week 3 of embryonic development, the mesoderm becomes organized into separate tissue regions. An amnionic cavity forms. Which of the following portions of mesoderm surrounds this amnionic cavity?

A Lateral plate

B Paraxial

C Parietal

D Splanchnic

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Question 36

A 41-year-old woman has a serum "triple screen" performed that shows normal levels of unconjugated estriol and human chorionic gonadotropin, but markedly increased alpha-fetoprotein. Acetylcholinesterase is also increased. Fetal ultrasound at 18 weeks gestation shows diminished movement of lower extremities. Which of the following abnormalities is most likely to be present in her fetus?

A Agenesis of the corpus callosum

B Arnold-Chiari malformation

C Holoprosencephaly

D Hydrocephalus

E Microcephaly

F Spina bifida

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Question 37

During embryonic development, neural crest cells migrate to the skin. These cells can produce melanin from tyrosine. These cells may be destroyed in a patchy distribution by an autoimmune process. What is the most likely condition to result from this autoimmune process?

A Albinism

B Atrichia

C Ichthyosis

D Polythelia

E Vitiligo

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Question 38

A neonate born at term is noted at 1 week of age to exhibit cyanosis. On examination no murmur is auscultated. The oxygen saturation is 60%. Which of the following abnormalities in cardiac development best explains these findings?

A Absence of the septum secundum

B Complete fusion of the aortic valve

C Conotruncal ridges fail to fuse

D Defect in the membranous interventricular septum

E Ductus arteriosus fails to close postpartum

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Question 39

A newborn boy infant born at term is noted to have clear fluid leaking from his umbilical region. In contrast, there is minimal urine output via the penis onto the diaper. The pH of the leaking fluid is 6.5. Which of the following is the most likely abnormality in this boy?

A Bladder exstrophy

B Gastroschisis

C Hypospadias

D Omphalocele

E Patent vitelline duct

F Urachal sinus

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Question 40

A 24-year-old primigravida has felt no fetal movement at 16 weeks gestation. A screening fetal ultrasound shows anhydramnios and a single poorly formed lower extremity. An abnormality involving which of the following structures most likely led to these findings?

A Aorta

B Dermis

C Neural crest

D Splanchnic mesoderm

E Zone of proliferating activity

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Question 41

Cells from the dorsolateral portion of a somite form a ventral hypomere with myotomes. Which of the following portions of the nervous sysem form nerves that migrate with the myotomes during development?

A Dorsal primary ramus

B Ventral primary ramus

C Dorsal root ganglion

D Sympathetic ganglion

E Grey communicating ramus

F White communicating ramus

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Question 42

A 44-year-old woman gives birth at 34 weeks gestation to a low birth weight male infant. On examination there is brachycephaly and uplanting palpebral fissues. There is a cleft in the iris bilaterally. Which of the following terms describes the defect in the iris of this infant?

A Aniridia

B Anophthalmia

C Aphakia

D Cataract

E Coloboma

F Cyclopia

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Question 43

A triple screen at 16 weeks gestation shows an elevated maternal serum alpha-fetoprotein with normal acetylcholinesterase. A fetal ultrasound shows a lateral abdominal wall defect through which bowel herniates. There is no sac covering the herniated tissue. There is a thin band connecting the edge of the defect with the left hand, and the thumb is absent where it attaches. What is the best description for this abdominal wall defect?

A Diaphragmatic hernia

B Gastroschisis

C Meckel diverticulum

D Omphalocele

E Patent urachus

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Question 44

A screening fetal ultrasound at 18 weeks gestation shows decreased size. On each hand digits 3 and 4 (middle and ring fingers) appear fused. The placenta shows focal echogenic areas. Chromosome analysis shows a 69, XXY karyotype. What is the best description for the anomaly seen in the hands of this fetus?

A Brachydactyly

B Camptotactyly

C Clinodactyly

D Polydactyly

E Syndactyly

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Question 45

A 1-month-old infant has failure to thrive. On examination a heart murmur is auscultated over the chest. No cyanosis is noted. Echocardiography shows a left-to-right shunt just above the muscular interventricular septum. An abnormality of which of the following structures most likely produced this infant's defect?

A Chordae tendineae

B Crista terminalis

C Endocardial cushion

D Septum primum

E Sinus venosus

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Question 46

A 19-year-old primigravida notes minimal fetal movement at 17 weeks gestation. The maternal serum alpha-fetoprotein is not increased. Fetal ultrasound shows enlargement of lateral ventricles of the brain. Which of the following abnormalities is the most likely cause?

A Aqueduct of Sylvius stenosis

B Craniorachischisis

C Exencephaly

D Holoprosencephaly

E Spina bifida

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Question 47

In the normally developing embryo, the mesonephric duct gives rise to the ureteric bud. The excretory system develops from migration of the ureteric bud into metanephric tissue. Which of the following renal components has aquaporin receptors and is derived from the ureteric bud?

A Collecting ducts

B Glomerular visceral epithelium

C Loops of Henle

D Mesangial cells

E Proximal convoluted tubules

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Question 48

At 24 weeks gestation, a developing tooth had multiple layers of tissue. Which of the following layers contains a vascular component?

A Cementum

B Dentin

C Enamel

D Periodonal ligament

E Pulp

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Question 49

A 4-year-old child has had nausea and vomiting for the past year. She exhibits early satiety with meals. An abdominal ultrasound is performed and shows duodenal narrowing. Abnormal migration of which of the following structures most likely occurred in this girl when she was in utero?

A Hepatic diverticulum

B Intestinal duplication

C Septum transversum

D Superior mesenteric artery

E Ventral pancreatic bud

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Question 50

A neonate born at term after an uncomplicated pregnancy is noted to pass pale coloured stool and dark urine. The infant becomes progressively jaundiced in the next 2 days. On examination the infant is at the 50th percentile for weight. Icterus is present. The serum IgM antibody titer to cytomegalovirus is increased. Which of the following developmental abnormalities most likely occurred in utero?

A Accessory pancreas

B Biliary atresia

C Gallbladder duplication

D Hepatic agenesis

E Intestinal malrotation

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Question 51

Following birth, circulation from placenta to fetus ceases. Which of the following fetal structures that conducts blood to the inferior vena cava becomes atretic in postnatal life?

A Azygous vein

B Ductus arteriosus

C Ductus venosus

D Foramen ovale

E Umbilical artery

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Question 52

A newborn at term is examined. The examiner's thumb is placed over the infant's inner thigh, and the index finger is gently placed over the greater trochanter. The hip is abducted, and gentle pressure is placed over the greater trochanter. A 'clunk' is heard. Which of the following structures is most likely to be abnormally developed in this neonate?

A Acetabulum

B Femoral condyle

C Femoral neck

D Iliac crest

E Ischial tuberosity

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