Embryology Test 2 Practive from BRS

1. The surface ectoderm gives rise to which of the following structures? (A) Dilator pupillae muscle (B) Retina (C) Lens (D) Sclera (E) Choroid

1. C. The lens forms from the lens placode that is induced by the optic cup.

4. Smooth muscle, connective tissue, and cartilage of primary bronchi are derived from which one of the following sources? (A) Neuroectoderm (B) Endoderm (C) Ectoderm (D) Visceral mesoderm (E) Mesoderm of pharyngeal arches 4 and 6

4. D. The epithelium of primary bronchi is derived from endoderm; the other components are derived from visceral mesoderm.

5. The most common type of anorectal malformation is (A) imperforate anus (B) anal agenesis (C) anorectal agenesis (D) rectal atresia (E) colonic aganglionosis

5. C. The most common type of malformation involving the anal canal and rectum is anorectal agenesis, in which the rectum ends as a blind sac above the puborectalis muscle. The anal canal may form normally but does not connect with the rectum. This malformation is accompanied by various fistulas.

Hyperoxygenation of premature may result in infants (A) congenital glaucoma (B) microphthalmia (C) coloboma (D) retrolental fibroplasia (E) persistent pupillary membrane

5. D. Retrolental fibroplasia results from hyperoxygenation of premature infants. In premature infants, high oxygen concentration results in vaso-obliteration of the terminal arterioles, leading to hemorrhage and infarction of the retina. This phenomenon is peculiar to the incompletely vascularized peripheral retina.

5. The stapedius muscle that moves the stapes ossicle is innervated by (A) CN V3 (B) CN XII (C) CN III (D) CN VII (E) cervical nerves C2 and C3

5. D. The stapes is innervated by CN VII (facial nerve)

8. Which one of the following structures is derived from the midgut? (A) Appendix (B) Stomach (C) Liver (D) Pancreas (E) Sigmoid colon

8. A. The appendix is derived from the midgut. The midgut normally undergoes a 270° counterclockwise rotation during development; malrotation of the midgut may result in the appendix lying in the upper part of the abdominal cavity, which may affect a diagnosis of appendicitis.

What condition is associated with dysphonia, laryngeal stridor, respiratory arrest due to stretching of CNX and CNXII, and a lumbar meningomyelocele(Spina Bifida cystica)?

Arnold-Chiary phenomenon (congenital anomaly)

At birth, the conus medularis can be found at which vertebral level?

At birth, the conus medullaris extends to L3. in an adult it extends to L1-L2 interspace. At 8 weeks, the spinal cord extens the entire length of the vertebral canal. At week 24 it extends to S1.

What is associated with the atresia of foramen of Magendie and formanina of Luschka?

Dandy walker syndrome

The maternal and fetal components of the placenta are:

Decidua basalis and villous chorion:

The intervillous space of the placenta contains:

Maternal blood and spiral arteries of the endometrium which penetrate the outer cytotrophoblast shell.

Which of the following is the most common cause of congenital hydrocephalus? (a) cranium bifidum with meningoencephalocele (b) Cranium bifidum with meningohydroencephalocele (c) Aqueductal stenosis (d)arnold-Chiari syndrom (e) Dandy-walker syndrome

(C) the most common cause of congential hydrocephalus is aqueductal stenosis Note that 50% of those with Arnold-Chiari syndrome also have aqueductal stenosis.

Which of the following most accurately describes the herniation of meninges and brain tissue through a defect in occipital bone? (a) cranium bifidum with meningoencephalocele (b) Cranium bifidum with meningohydroencephalocele (c) Cranium bifidum with meningocele (d)arnold-Chiari syndrom (e) Dandy-walker syndrome

(a) A cranium bifidum with meningoencephalocele consists of herniation of meninges and brain tissue through a defect in occipital bone. Meningocele may contain meninges. Menigohydroencephalocele may contain part of the brain, meninges, and part of the ventricular system.

The flexure that develops between the metencephalon and the myelencephalon is called? (a) cephalic flexure (b) mesencephalic flexure (c) pontine flexure (d) cerebellar flexure (e) cervical flexure

(c) the pontine flexure cephalic (midbrain) flexure is between prosencephalon and rhombencephalon Cervical flexure is between rhombencephalon and future spinal cord

Caudal herniation of the cerebellar tonsils and medulla through the foramen magnum is called? (a) Dandy-Walker syndrome, (b) Down Syndrome, (c) Arnold-Chiari syndrome

(c)Arnold-Chiari syndrome is a cerebellomedullary malformation in which the caudal vermis and medulla herniate through the foramen magnum, resulting in communicating hydrocephalus. Arnold-Chiari syndrome is frequently associated with spina bifida. Dandy-Walker syndrome is a congenital hydrocephalus associated with atresia of the outlet foramine of Luschka and Magendie. Associated with dilation of the 4th ventricle, agenesis of the cerebellar vermis, occipital meningocele, and frequently agenesis of the splenium of the corpus callosum.

1. Pancreatic islets consist of alpha, beta, and delta cells, which secrete glucagon, insulin, and somatostatin, respectively. These cells are derived from (A) mesoderm (B) endoderm (C) ectoderm (D) neuroectoderm (E) neural crest cells

1. B. Pancreatic islets form as isolated clumps of cells that bud from endodermal tubules.

1. A young mother brings her recently born infant into your office and complains that the infant gags and chokes after swallowing milk. A physical examination indicates excessive saliva and mucus around the mouth and nose, abdominal distention, pneumonitis, and radiographs indicate air in the infant's stomach. What is the most likely cause? (A) Hypertrophic pyloric stenosis (B) Tracheoesophageal fistula (C) Congenital lobar emphysema (D) Respiratory distress syndrome (E) Pulmonary hypoplasia

1. B. Tracheoesophageal fistula is an abnormal communication between the trachea and esophagus that results from an improper division of the foregut by the tracheoesophageal septum. It is generally associated with esophageal atresia and polyhydramnios.

1. The most common site of a thyroglossal cyst is the (A) dorsal aspect of neck (B) anterior border of sternocleidomastoid muscle (C) superior mediastinum (D) midline close to the hyoid bone (E) base of the tongue

1. D. The thyroid gland forms from a diverticulum in the midline of the floor of the pharynx. The thyroid migrates caudally and passes ventral to the hyoid bone. During this migration, the thyroid remains connected to the tongue by the thyroglossal duct. If a part of the thyroglossal duct persists, a cyst develops, usually near the hyoid bone.

1. The cochlear duct contains the spiral organ of Corti and is derived from which of the following? (A) Both ectoderm and mesoderm (B) Neural crest (C) Endoderm (D) Mesoderm (E) Ectoderm

1. E. The cochlear duct is derived from a thickening of the surface ectoderm called the otic placode.

10. The midgut loop normally herniates through the primitive umbilical ring into the extraembryonic coelom during week 6 of development. Failure of the intestinal loops to return to the abdominal cavity by week 11 results in the formation of (A) omphalocele (B) gastroschisis (C) anal agenesis (D) ileal diverticulum (E) intestinal stenosis

10. A. An omphalocele results when intestinal loops fail to return to the abdominal cavity. Instead, the intestinal loops remain in the umbilical cord covered by amnion.

10. Pharyngeal groove 1 gives rise to the (A) internal auditory meatus (B) external auditory meatus (C) eustachian tube (D) cervical sinus (E) primary tympanic cavity

10. B. Pharyngeal groove 1 gives rise to the external auditory meatus.

What is the normal mount of amniotic fluid at term?

1000mL (recall oligohydramnios is 400mL in late pregnancy and could be indicative of renal agenesis)(polyhydramnios is 2000mL in late pregnancy and could be indicative or either anenchephaly of esophageal atresia)

11. Kupffer cells present in the adult liver are derived from (A) mesoderm (B) endoderm (C) ectoderm (D) neuroectoderm (E) neural crest cells

11. A. Kupffer cells are actually macrophages and are derived from mesoderm. Hepatocytes and the epithelial lining of the intrahepatic biliary tree are derived from endoderm.

12. The simple columnar and stratified columnar epithelia lining the lower part of the anal canal is derived from (A) mesoderm (B) endoderm (C) ectoderm (D) neuroectoderm (E) neural crest cells

12. C. The anal canal is formed from two components, the hindgut and proctodeum. The epithelium lining the lower anal canal is derived from ectoderm lining the proctodeum.

13. A baby born to a young woman whose pregnancy was complicated by polyhydramnios was placed in the intensive care unit because of repeated vomiting containing bile. The stomach was markedly distended, and only small amounts of meconium had passed through the anus. What is the most likely diagnosis? (A) Esophageal stenosis (B) Annular pancreas (C) Hypertrophic pyloric stenosis (D) Extrahepatic biliary atresia (E) Duodenal atresia

13. E. This baby is suffering from duodenal atresia at a level distal to the opening of the common bile duct. This causes a reflux of bile and its presence in the vomitus. The pregnancy was complicated by polyhydramnios because the duodenal atresia prevented passage of amniotic fluid into the intestines for absorption.

2. Within hours after birth, a baby, whose mother is diabetic, had a rising respiratory rate and labored breathing. The baby became cyanotic and died. Postmortem histologic examination revealed collapsed alveoli lined with eosinophilic material. What is the diagnosis? (A) Congenital emphysema (B) Respiratory distress syndrome (C) Cystic fibrosis (D) Tracheoesophageal fistula (E) Pulmonary carcinoma

2. B. Respiratory distress syndrome is common in premature infants and infants of diabetic mothers. It is caused by a deficiency or absence of surfactant. Collapsed alveoli and eosinophilic material consisting of fibrin (hyaline membrane) can be observed histologically, indicating associated hyaline membrane disease.

2. Taste sensation from the oral part (anterior two thirds) of the tongue is predominantly carried by the (A) trigeminal nerve (CN V) (B) chorda tympani branch of the facial nerve (CN VII) (C) glossopharyngeal nerve (CN IX) (D) superior laryngeal branch of the vagus nerve (CN X) (E) recurrent laryngeal branch of the vagus nerve (CN X)

2. B. Taste sensation from the mucosa for the oral part of the tongue is carried by the chorda tympani branch of the facial nerve (CN VII). This part of the tongue forms from pharyngeal arch 1, so the trigeminal nerve (CN V) will carry sensory innervation from the mucosa.

2. The middle ear cavity (A) is of mesodermal origin (B) develops from pharyngeal pouch 1 (C) develops from pharyngeal arch 1 (D) develops from pharyngeal arch 2 (E) develops from the otic vesicle

2. B. The middle ear cavity develops from pharyngeal pouch 1 as it evaginates to form the tubotympanic recess.

2. Failure of the choroid fissure to close results in (A) congenital detached retina (B) congenital aniridia (C) congenital aphakia (D) coloboma iridis (E) microphthalmos

2. D. Failure of the choroid (optic) fissure to close results in a cleft of the iris, a coloboma iridis. This defect may extend into the ciliary body, choroid, optic nerve, or retina. Congenital aphakia, absence of the lens, may result from defective development of the lens placode.

2. A 2-month-old baby with severe jaundice also has dark-colored urine (deep yellow) and white clay-colored stool. Which of the following disorders might be suspected? (A) Esophageal stenosis (B) Annular pancreas (C) Hypertrophic pyloric stenosis (D) Extrahepatic biliary atresia (E) Duodenal atresia

2. D. The baby is suffering from extrahepatic biliary atresia, which results from failure of the bile ducts to recanalize during development. This prevents bile from entering the duodenum.

3. The trachea is lined with pseudostratified ciliated columnar epithelium with goblet cells. This epithelium is derived from (A) neuroectoderm (B) endoderm (C) ectoderm (D) visceral mesoderm (E) mesoderm of fourth and sixth pharyngeal arches

3. B. The epithelial lining of the entire respiratory system (from tracheal epithelium to Type I pneumocytes lining alveoli) is derived from endoderm.

3. The optic cup is an evagination of which of the following? (A) Telencephalon (B) Diencephalon (C) Mesencephalon (D) Metencephalon (E) Myelencephalon

3. B. The optic cup and its derivatives, the retina and optic nerve, develop from the diencephalon.

3. The otic vesicle (A) gives rise to the bony labyrinth (B) is found adjacent to the rhombencephalon (C) is derived from neuroectoderm (D) gives rise to the auricle (pinna) (E) gives rise to the tympanic membrane

3. B. The otic vesicle arises from an invagination of the surface ectoderm called the otic placode. The otic vesicle is found adjacent to the rhombencephalon.

3. A 28-day-old baby is brought to the physician because of projectile vomiting after feeding. Until this time, the baby has had no problems in feeding. On examination, a small knot is palpated at the right costal margin. Which of the following disorders might be suspected? (A) Esophageal stenosis (B) Annular pancreas (C) Hypertrophic pyloric stenosis (D) Extrahepatic biliary atresia (E) Duodenal atresia

3. C. The baby is suffering from hypertrophic pyloric stenosis. This occurs when the smooth muscle in the pyloric region of the stomach hypertrophies and obstructs passage of food. The hypertrophied muscle can be palpated at the right costal margin. The exact cause of this condition is not known.

3. The intermaxillary segment forms via the fusion of the (A) maxillary prominences (B) mandibular prominences (C) palatine shelves (D) lateral nasal prominences (E) medial nasal prominences

3. E. The intermaxillary segment, which plays a critical role in the formation of the definitive adult palate, forms when the two medial nasal prominences fuse in the midline.

4. Which of the following arteries supplies foregut derivatives of the digestive system? (A) Celiac trunk (B) Superior mesenteric artery (C) Inferior mesenteric artery (D) Right umbilical artery (E) Intercostal artery

4. A. The artery that supplies foregut derivatives of the digestive system is the celiac trunk. The celiac trunk consists of the left gastric artery, splenic artery, and common hepatic artery. The superior mesenteric artery supplies the midgut, and the inferior mesenteric artery supplies the hindgut.

4. The auricle (pinna) of the external ear is innervated by which of the following nerves? (A) CN V3 (B) CN V2 (C) CN XII (D) CN III (E) CN VIII

4. A. The auricle (pinna) of the external ear is innervated by cranial nerves V3 (mandibular division), VII, IX, and X; cervical nerves C2 and C3 also innervate the auricle.

4. The most common site of a pharyngeal fistula is the (A) dorsal aspect of neck (B) anterior border of sternocleidomastoid muscle (C) superior mediastinum (D) midline close to the hyoid bone (E) base of the tongue

4. B. A pharyngeal fistula forms when pharyngeal pouch 2 and pharyngeal groove 2 persist. Therefore, these fistulas are found on the lateral aspect of the neck, usually along the anterior border of the sternocleidomastoid muscle.

4. The epithelium of the ciliary body derived from (A) ectoderm (B) mesoderm (C) endoderm (D) neuroecloderm (E) neural crest cells

4. D. The ciliary body is derived from the anterior two layers of the optic cup (neuroectoderm), which form the epithelium and form an anterior extension of the choroid (mesoderm).

5. What is the most common congenital malformation of the head and neck region? (A) Anterior cleft palate (B) Posterior cleft palate (C) Thyroglossal duct cyst (D) Unilateral cleft lip (E) Ankyloglossia

5. D. Unilateral cleft lip is the most common congenital malformation of the head and neck. Cleft lip occurs when the maxillary prominences fail to fuse with the medial nasal prominences and when the underlying somitomeric mesoderm and neural crest fail to proliferate, resulting in a persistent labial groove. Cleft lip occurs in 1 of 900 births and may be unilateral or bilateral.

5. Components of the blood-air barrier in the lung are derived from which of the following sources? (A) Ectoderm only (B) Visceral mesoderm only (C) Visceral mesoderm and ectoderm (D) Endoderm and ectoderm (E) Visceral mesoderm and endoderm

5. E. The blood-air barrier comprises the structures through which gaseous exchange occurs between air in alveoli and blood in pulmonary capillaries. The attenuated pulmonary epithelium (Type I pneumocytes) is derived from endoderm. The simple, squamous epithelium (endothelium) lining pulmonary capillaries is derived from visceral mesoderm.

6. Which pharyngeal arch is associated with Treacher Collins syndrome? (A) Pharyngeal arch 1 (B) Pharyngeal arch 2 (C) Pharyngeal arch 3 (D) Pharyngeal arch 4 (E) Pharyngeal arch 6

6. A. First arch syndrome results from abnormal development of pharyngeal arch 1 due to a lack of migration of neural crest cells. Treacher Collins syndrome is associated with underdevelopment of the zygomatic bone, down-slanting palpebral fissures, and deformed lower eyelids and external ears.

6. The simple columnar or cuboidal epithelium lining the extrahepatic biliary ducts is derived from (A) mesoderm (B) endoderm (C) ectoderm (D) neuroectoderm (E) neural crest cells

6. B. The epithelium lining the extrahepatic biliary ducts is derived from endoderm. The intrahepatic biliary ducts are also derived from endoderm.

6. The utricular portion of the otic vesicle gives rise to the (A) ductus reuniens (B) cochlear duct (C) endolymphatic sac (D) scala vestibuli (E) scala tympani

6. C. The utricular region of the otic vesicle gives rise to the endolymphatic sac and duct, and semicircular ducts.

6. The respiratory diverticulum initially is in open communication with the primitive foregut. Which of the following embryonic structures is responsible for separating these two structures? (A) Laryngotracheal groove (B) Posterior esophageal folds (C) Laryngotracheal diverticulum (D) Tracheoesophageal septum (E) Bronchopulmonary segment

6. D. When the tracheoesophageal folds fuse in the midline, they form the tracheoesophageal septum. This septum is responsible for separating the adult trachea ventrally from the esophagus dorsally.

6. The optic nerve is a tract of the diencephalon that is not completely myelinated until (A) 5 years after birth (B) 2 years after birth (C) 1 year after birth (D) 3 weeks after birth (E) 3 months after birth

6. E. The axons of the optic nerve are not completely myelinated until 3 months after birth. Myelinated axons are normally not found in the retina. The optic nerve is not a true peripheral nerve but a tract of the diencephalon; when severed, the optic nerve does not regenerate. Myelination in the CNS is accomplished by oligodendrocytes; oligodendrocytes are not found in the retina.

7. The saccular portion of the otic vesicle gives rise to the (A) organ of Corti (B) endolymphatic duct (C) superior semicircular canal (D) crus commune nonampullare (E) lateral semicircular canal

7. A. The saccular region of the otic vesicle gives rise to the cochlear duct, which houses the spiral organ of Corti.

7. Collapsed bronchi caused by failure of bronchial cartilage development is indicative of which one of the following congenital malformations? (A) Congenital bronchial cysts (B) Congenital neonatal emphysema (C) Tracheoesophageal fistula (D) Hyaline membrane disease (E) Pulmonary hypoplasia

7. B. Congenital neonatal emphysema is a malformation involving the bronchi. One or more lobes of the lungs are overdistended with air because air can be inspired through collapsed bronchi, but cannot be expired.

7. During surgery for removal of a thyroid tumor, a number of small masses of glandular tissue are noted just lateral to the thyroid gland. Metastasis from the thyroid tumor is suspected, but histologic analysis of a biopsy reveals parathyroid tissue and remnants of thymus. How can this finding be explained? (A) Tumor tissue has differentiated into normal tissue (B) A parathyroid gland tumor is also present (C) Ectopic glandular tissue is commonly found in this region (D) Patient has DiGeorge syndrome (E) The glandular tissue is a result of a thyroglossal duct cyst

7. C. The parathyroid and thymus migrate in a caudal and medial direction during development; therefore, ectopic glandular tissue may be found anywhere along the migratory path.

7. A 4-day-old baby boy has not defecated since coming home from the hospital even though feeding has been normal without any excessive vomiting. Rectal examination reveals a normal anus, anal canal, and rectum. However, a large fecal mass is found in the colon, and a large release of flatus and feces follows the rectal examination. Which of the following conditions would be suspected? (A) Imperforate anus (B) Anal agenesis (C) Anorectal agenesis (D) Rectal atresia (E) Colonic aganglionosis

7. E. This baby boy suffers from colonic aganglionosis, or Hirschsprung disease, which results in the retention of fecal material, causing the normal colon to enlarge. The retention of fecal material results from a lack of peristalsis in the narrow segment of colon distal to the enlarged colon. A biopsy of the narrow segment of colon would reveal the absence of parasympathetic ganglion cells in the myenteric plexus caused by failure of neural crest migration.

8. Pulmonary hypoplasia is commonly associated with which condition? (A) Hyaline membrane disease (B) Diaphragmatic hernia (C) Tracheoesophageal fistula (D) Congenital bronchial cysts (E) Congenital neonatal emphysema

8. B. During normal development, a space is provided for the prolific growth of the bronchial buds in a lateral and caudal direction. This space, which is part of the intraembryonic coelom, is called the primitive pleural cavity. If this space is reduced by herniation of abdominal viscera, lung development will be severely compromised.

8. Aqueous humor is produced by the (A) choroid plexus (B) trahecular meshwork (C) ciliary processes (D) vitreous body (E) lens vesicle

8. C. Aqueous humor is produced by the ciliary processes of the ciliary body. It flows from the posterior chamber, through the pupil, into the anterior chamber, and finally to the canal of Schlemm, which empties into the extraocular veins.

9. Aqueous humor enters the venous circulation via (A) arachnoid villi (B) scleral canal (C) hyaloid canal (D) canal of Schlemm (E) Cloquet's canal

9. D. Aqueous humor enters the venous circulation via the canal of Schlemm. Blockage of this canal results in increased intraocular pressure (glaucoma).

9. A 3-month-old baby girl presents with a swollen umbilicus that has failed to heal normally. The umbilicus drains secretions, and there is passage of fecal material through the umbilicus at times. What is the most likely diagnosis? (A) Omphalocele (B) Gast roschisis (C) Anal agenesis (D) Ileal diverticulum (E) Intestinal stenosis

9. D. This baby girl has an ileal diverticulum (Meckel's diverticulum), which occurs when a remnant of the vitelline duct persists. In this case, a fistula is present whereby contents of the ileum can be discharged onto the surface of the skin.

9. Development of which one of the following is the first sign of respiratory system development? (A) Tracheoesophageal septum (B) Hypobranchial eminence (C) Primitive foregut (D) Tracheoesophageal fistula (E) Respiratory diverticulum

9. E. Development of the respiratory system begins in week 4; the first sign of development is formation of the respiratory diverticulum in the ventral wall of the primitive foregut.

A 26-year-old pregnant woman experience episodes of bright red vaginal bleeding at week 28, week 32, and week 34 of pregnancy. The bleeding spontaneously subsided each time. Using ultrasound, the placenta is located in the lower right portion of the uterus over the internal os. What is the diagnosis?

A placenta implanted in the lower part of the uterus near the internal os is called the planta previa.

Which of the following does not pass through the primitive umbilical ring? Allantois, amnion, yolk sac, connecting stalk, space connecting the intra/extraembryonic coeloms, IgG

Amnion does not pass through the primitive umbilical ring.

Anterior and posterior neuropores close during which week of embryonic development?

During week 4. The anterior on day 24 (failure to close results in anencephaly or meningoencephalocele); Posterior closes on day 26 at somite 31 (failure to close results in spina bifida)

A young insulin-dependent diabetic women in her first pregnancy is concerned that her daily injection of insulin will cause a congenital malforamtion in her baby. Wht shoudl the physician tell her?

Insulin, like all protein hormones, does not cross the placental membrane in significant amounts. (except transferin made my the mother which is a protein and can cross)

Which of the structures are derived from the telencephalon? Pineal gland, hypothalamus, hippocampus, optic nerve (CNII) or globus pallidus?

The hippocampus develops from the telencephalon. The pineal, and structures related to the thalamus, or the eye will be derived from the diencephalon.

Which of the following are derived from the diencephalon? Caudate nucleus, cerebellum, olfactory bulbs, neurohypohysis, adenohypophysis?

The neurohypophysis develops from the diencephalon. The adenohypophysis develops from the Rathke's pouch, and ectodermal diverticulum of the stomodeum. The caudate nucleus and olfactory bulbs develop from the telencephalon. The cerevellum from the metencephalon.

10. In a detached retina, the site of detachment is found (A) within the outer plexiform layer (B) within the inner plexiform layer (C) between the inner nuclear layer and the outer nuclear layer (D) between the choriocapillaris and the pigment epithelial layer (E) between the pigment epithelial layer and the layer of outer segments of rods and cones

outer segments M rods and cones; this corresponds to the intraretinal space between the inner and outer layers of the optic cup. Retinal detachment occurs when fluid from the vitreous compartment passes through a retinal hole and separates the pigment epithelial layer from the layer of outer segments of rods and cones.