Embryology

Question 1

Endoderm

Answer 1

gut, liver, lungs, thyroid, tonsils, parathyroid glands

Question 2

Mesoderm

Answer 2

skeleton, muscle, kidney, heart, blood, gonads, cartilage, dermis, circulatory system body cavity

Question 3

ectoderm

Answer 3

skin, nervous system

Question 4

Hydatidiform Mole

Answer 4

formed from trophoblast (outer layer)
Appearance of grape like clusters
Defect in paternal genome (genomic imprinting)
secrete high levels of hcg - syncytiotrophoblast
may become invasive (choriocarcinoma)

Question 5

hydatidiform mole may become

Answer 5

choriocarcinoma

Question 6

teratoma

Answer 6

mass from remnants of primitive streak usually in sacral region
multiple tissue types- ectoderm, endoderm, mesoderm
3x more common in female fetuses

Question 7

Ectopic pregnancy- most common site

Answer 7

ampulla of tube

tubal implantation

Question 8

ectopic pregnancy most commonly seen in women who

Answer 8

have had endometriosis, prior surgery, pelvic inflammatory disease

Question 9

skin layers

Answer 9

epidermis: ectoderm
dermis: mesoderm-somatopleure and dermatome
melanocytes: neural crest cells
langerhans cells: mesoderm

Question 10

Waardenburg syndrome

Answer 10

disrupted differentiation of neural crest cells- cause hearing loss and changes in coloring (pigmentation) of hair, skin, eyes

• eyes are pale blue or different colored
• patch of white hair

Question 11

Piebaldism

Answer 11

rare autosomal dominant disorder of melanocyte development characterized by congenital white forelock and multiple symmetrical hypopigmented or depigmented macules

Question 12

RET proto oncogene

Answer 12

expressed by neural crest cells and encodes tyrosine kinase- provides instructions for producing signaling protein which is essential for normal development of several inds of neurons (including those in intestine) and autonomic control of functionss uch as heart rate, normal renal development and spermatogenesis

Question 13

Most common cause congenital hydrocephalus

Answer 13

aqueductal stenosis- dilated lateral ventricles, normal 4th ventricle.

dilated 4th ventricle and normal 3rd and laterl ventricles- dandy walker syndrome or obstruction of foramina of luschka and Magendie

Question 14

Hydrocephalus CF

Answer 14

enlarged cerebral ventricles, mental retardation, spastic paraparesis, adducted thumbs
may occur as chromosomal abnormality, prenatal infection, non-genetic structural anomaly

Question 15

craniopharyngiomas

Answer 15

derived from oral ectoderm (rathke’s pouch)
impinge upon pituitary stalk resulting in absence of ADH and diabetes insipidus
Can also cause bitemporal hemianopia (loss of visual field on the same side

Question 16

Cerebellar cortical development

Answer 16

external granule layer is proliferative zone from which cells migrate inwards (away from surface)

Question 17

cerebral cortical development

Answer 17

pyramidal neurons radially migrate toward superficial layer
(inside out pattern of formation)
earliest neurons formed are placed in deepest layers
early part- multi polar neurons with many neurites which then change to bipolar neurons

Question 18

cerebellum function

Answer 18

coordinate timing and force of muscular contractions so that skilled, voluntary movements are appropriate
integrates information into execution of movement

Question 19

Spinal bifida meningocele

Answer 19

contains meninges with csf

Question 20

spina bifida meningomyelocele

Answer 20

meninges and spinal cord

Question 21

spina bifida myeloschisis or rachischisis

Answer 21

neural tube has not closed, severe sensory and motor deficits

Question 22

spina bifida occulta

Answer 22

defect in vertebral arch without a cyst

tuft of hair on back

Question 23

Anencephaly

Answer 23

crania bifida- neural folds do not fuse in the cranial region of neural tube (failure of cranial neuropore to close)

skull never forms, brain tissue degenerates while in contact with amniotic fluid

Question 24

most likely site of detachment of retina

Answer 24

between pigmented epithelial layer and rods and cones

Question 25

connexin 26 mutation

Answer 25

Connexin proteins are gap-junction proteins that are necessary for cells to communicate with eachother- without sufficient levels of connexin 26, potassium flow from hair cells in cochlea is disrupted, resulting in high levels of K in organ of corti--> profound sensorineural hearing loss

Question 26

Ectodermal dysplasia

Answer 26

teeth do not develop properly because they arise from ectoderm of oral cavity as do hair follicles inability to tolerate heat due to lack of sweat glands

Question 27

foregut contents

Answer 27

celiac artery stomach, liver, gall bladder, first 1/2 of duodenum, pancreas (spleen is the exception because it's mesoderm derived)

Question 28

midgut contents

Answer 28

superior mesenteric artery | second 1/2 of duodenum, SI, proximal large intestine

Question 29

hindgut contents

Answer 29

inferior mesenteric artery | distal large intestine, sigmoid colon, rectum/anorectal canal

Question 30

duodenal atresia and stenosis due to

Answer 30

incomplete recanalization or by vascular accidents- gut strangulations from malrotation, volvulus, omphalocele atresia- parts 2 and 3 of duodenum stenosis- parts 3 and 4 vomit bile upon overfilling of duodenum with bile because no place for bile to pass distally

Question 31

blood supply to duodenum is

Answer 31

dual first half- celiac artery second half- sma

Question 32

apple peel atresia

Answer 32

10% of all atresias | in proximal jejunum, intestine is short, with portion distal to lesion coiled around mesenteric remnant

Question 33

annular pancreas

Answer 33

bilobed ventral pancreatic bud is formed, buds migrate around duodenum in opposite directions strangulating duodenum which can lead to duodenual stresia/stenosis

Question 34

malrotation of gut

Answer 34

gut did not rotate normally can be in varying degrees of strangulation, resulting in varying degrees of vascular compromise increased change of tissue necrosis occurring with increasing severity

Question 35

mecke's diverticulum/fistula/cyst

Answer 35

stalk of yolk sac remains attached to body wall and can be patent or not or cyst like generally- ileal but can be gastric/pancreatic/colonic

Question 36

positioinal anomalies

Answer 36

complete/ partial situs inversus

Question 37

gastroschisis

Answer 37

failure of ventral body wall to close properly | loops herniate directly through abdominal wall into abdominal cavity

Question 38

omphalocele

Answer 38

failure of part of developing gut to return to abdominal cavity following its normal herniation into umbilical cord- defect is covered by reflection of amnion by umbilical cord

Question 39

congenial megacolon- hirschsprung disease

Answer 39

anomaly in craniocaudal migration of neural crest cells mutations in RET protooncogene involved sometimes lack of ganglion cells in myenteric and submucosal plexuses in sigmoid colon or rectum segment becomes constricted, causing normal, proximal section of bowel to distend with feces

Question 40

malrotation with midgut volvulus

Answer 40

bilious emesis, abdominal distention, high pitched bowel sounds-> obstruction severely dilated sigmoid colon with "coffee bean" shape is very suggestive of volvulus

Question 41

hypertrophic pyloric stenosis

Answer 41

non-bilious emesis presenting 4-6 weeks after birth distended stomach caterpillar sign gastric outlet obstruction that results from congenital thickening of muscle of pylorus - results in narrowing of lumen of pylorus and outlet to the duodenum fluid restriction followed by pyloromyotomy is curative tx

Question 42

respiratory system

Answer 42

respiratory diverticulum is outgrowth of endodermal tube (foregut) epithelium is derived from endoderm cartilaginous, muscular, connective tissue components of trachea and lung are derived from splanchnic mesoderm

Question 43

tracheoesophageal septum

Answer 43

responsible for separating tracheal primodrium from esophageal primordium

Question 44

oligohydramnios

Answer 44

less urine output= less fluid 1) commonly due to early leaking of amniotic fluid due to premature rupture of membranes--> thoracic wall movement occuring with fetal breathing may be restricted- bad for lung development 2) also due to fetal rectal anomalies- amniotic fluids produced my fetal kidneys- polycystic kidneys, hydronephrosis, renal agenesis can cause oligohydramnios and are commonly associated with lung hypoplasia and limb malformations

Question 45

polyhydramnios

Answer 45

less swallowing=more fluid tracheoesophageal fistulae associated with polyhydramnios- blind esophagus is most common (proximal esophageal atresia with distal TEF)

Question 46

TEF complications

Answer 46

polyhydramnios pneumonitis pneumonia

Question 47

Potter sequence/syndrome

Answer 47

``` bilateral renal agenesis oligohydramnios lung hypoplasia clubbed feet, bowing of legs potter's facies- prominent infraorbital folds, flattened nose, parrot beak nose, recessed chin, skin crease, hypertelorism (inc distance between two organs like two eyes) growth retardation brachycephaly (shorter head) ```

Question 48

diaphragm develops from

Answer 48

septum transversum, pleuroperitoneal membranes, dorsal mesentery of esophagus, and lateral body walls muscle derived from 3, 4, 5th cervical somites motor innervation from C3, 4, 5 via phrenic nerve so is sensory

Question 49

most common congenital defect of diaphragm

Answer 49

congenital diaphragmatic hernia -defective formation and fusion of pleuroperitoneal membranes with other parts of diaphragm (usually on one side)- part of gut can pass through thorax, can cause hypoplastic development of lung left side of diaphragm involved 4-8 times more frequently probably because left pericardioperitoneal canal is larger and closes later can be corrected at birth and in utero, but severe pulmonary hypoplasia and insufficiency may be fatal diminished braeth sounds- usually at left side, heart sounds heart louder in right chest because mediastinum is displaced, abdomen is often scaphoid because abd contents are displaced into chest