Embryo Blue Boxes

Question 1

piriform sinus fistula

Answer 1

persistence of remnants of the ultimopharyngeal body along its path to the thyroid gland

Question 2

what are branchial vestiges?

Answer 2

cartilaginous or bony remnants of pharyngeal arch cartilages that appear under the skin in the side of the neck

Question 3

1st arch syndrome: in general, what is it and what causes it?

Answer 3

congenital anomalies of eyes, ears, mandable, and palate -caused by insufficient migration of neural crest cells into 1st arch during 4th week

Question 4

what are the two main manifestations of 1st arch syndrome?

Answer 4

1. Treacher Collins syndrome

2. Pierre Robin sequence

Question 5

what is Treacher Collins syndrome?

Answer 5

mandibulofascial dysostosis, autosomal dominant:

• malar hypoplasia
• down slanting palpebral fissures
• defects of lower eyelid
• deformed external ears
• some abnormalities of middle/internal ears

Question 6

what is the mutation associated with Treacher Collins syndrome?

Answer 6

mutation in TCOF1, which makes the protein treacle

Question 7

what is Pierre Robin syndrome?

Answer 7

autosomal recessive:

• hypoplasia of mandible (micrognathia)
• cleft palate
• defects of eye, ear

Question 8

what is DiGeorge syndrome?

Answer 8

• lack of thymus and parathyroid glands
• defects in cardiac outflow tracts
• lack of T cell fxn
• low set ears
• shortened philtrum of upper lip (fish mouth deformity)

Question 9

what causes DiGeorge syndrome?

Answer 9

3rd and 4th pharyngeal pouches fail to differentiate into thymus and parathyroid glands

Question 10

what is the most common metabolic disorder in neonates?

Answer 10

congenital hypothyroidism

Question 11

what is ankyloglossia?

Answer 11

short frenulum that extends to the tip of the tongue - interferes with its free protrusion, makes breast feeding difficult

Question 12

what is macroglossia?

Answer 12

excessively large tongue from hypertrophy of developing tongue - often seen in Down syndrome

Question 13

what is microglossia?

Answer 13

abnormally small tongue (rare) - usually associated with micrognathia and limb defects

Question 14

what is glossoschisis?

Answer 14

bifid or cleft tongue - incomplete fusion of lateral lingual swellings (uncommon)

Question 15

what is atresia of nasolacrimal duct?

Answer 15

when part of the nasolacrimal duct fails to canalize

Question 16

congenital auricular sinuses or cysts

Answer 16

located in a triangular area of skin anterior to auricle or external ear - minor anomaly

Question 17

what is congenital microstomia?

Answer 17

small mouth from excessive merging of mesenchymal masses in the maxillary and mandibular processes of the first pharyngeal arch

Question 18

what are oblique facial clefts?

Answer 18

• extend from upper lip to medial margin of orbit
• often bilateral
• nasolacrimal ducts are open grooves

Question 19

what are lateral or transverse facial clefts?

Answer 19

-run from mouth toward ear

Question 20

what is macrostomia?

Answer 20

large mouth - results from bilateral facial clefts

Question 21

what is cyclopia?

Answer 21

• single median eye enclosed in a single orbit

- usually have a tubular nose (proboscis) superior to eye

Question 22

what is synophthalmia?

Answer 22

fusion of eyes

Question 23

what is microphthalmia?

Answer 23

small eyes associated w/ other ocular defects

Question 24

severe vs. simple microphthalmos

Answer 24

severe -from arrested development of eye before or shortly after the optic vesicle has formed in 4th week

simple - development arrested in 8th week

Question 25

what is anophthalmia?

Answer 25

absence of an eye (unilateral or bilateral) | -eyelids form, but no eye present

Question 26

primary vs. secondary anophthalmos

Answer 26

primary: eye development arrested in 4th week, results from failure of optic vesicle to form secondary: development of forebrain suppressed -> includes many other defects

Question 27

what determines iris color?

Answer 27

concentration and distribution of chromatophores in the loose vascular CT of iris

Question 28

what is congenital aniridia?

Answer 28

lack of iris tissue or almost complete absence of iris - from arrested development at rim of optic cup (mutation in Pax6)

Question 29

what is persistent pupillary membrane?

Answer 29

web-like strands of CT or vascular arcades over the pupil | -especially in premies

Question 30

what is congenital atresia of the pupil?

Answer 30

entire pupillary membrane persists - absence of opening of pupil

Question 31

what is congenital aphakia?

Answer 31

absence of the lens

Question 32

what is congenital cataracts?

Answer 32

- opaque, grayish white lens - untreated = blindness - can be caused by rubella virus or congenital galactosemia

Question 33

what is cryptophthalmos?

Answer 33

congenital absence of the eyelids -> skin covers eyes | -autosomal recessive

Question 34

what are auricular appendages?

Answer 34

skin tags usually anterior to auricle - usually unilateral | -consist of skin

Question 35

what is anotia?

Answer 35

absence of the auricle - failure of mesenchymal proliferation

Question 36

what is microtia?

Answer 36

small or rudimentary auricle - from suppressed mesenchymal proliferation

Question 37

what causes atresia of the external acoustic meatus?

Answer 37

failure of the meatal plug to canalize

Question 38

what causes absence of external acoustic meatus?

Answer 38

failure of inward expansion of the 1st pharyngeal groove and failure of meatal plug to disappear

Question 39

what is congenital cholesteatoma?

Answer 39

fragment of keratinized epithelial cells "rest" that appears as a white cyst-like structure medial to and behind the tympanic membrane