Embryology Flashcards
1
Q
What does the truncus arteriosus (TA) form
A
Ascending aorta and pulmonary trunk
2
Q
What does bulbus cordi form?
A
Smooth par t(outflow tract) of left and right ventricles
3
Q
What do primitive atria form
A
Tracebulated part of lef tand right atria
4
Q
What do primitive ventricle form
A
Trabeculated part of L and R ventricles
5
Q
What does primitive pulm. vein form
A
Smooth part of L atrium
6
Q
L horn of sinus venosus (SV)
A
coronary sinus
7
Q
R horn of sinus venosus
A
Coronary sinus
8
Q
Right common cardinal vein and R anterior cardinal vein
A
SVC
9
Q
What is the first functional organ in vertebrate embryos
A
The heart, beats spontaneously by week 4 of development.
10
Q
When does heart tube loops gain polarity
A
Week 4 of gestation, establishing L-R polarity
11
Q
What can cause dextrocardia
A
Kartagener syndrome, defect in Left-Right dynein
12
Q
Primary ciliary dyskinesia
A
Kartageners
13
Q
Septation of the atria
A
Know the steps.
14
Q
What forms the atrial septum?
A
The fusing of the septum secundum and the remnant of the septum primum.
15
Q
What are the steps of ventricular septum formation?
A
First the muscular interventricular septum forms. Leaving a interventricular foramen. The aorticopulmonary septum rotates then fuses with muscular interventricular septum to form the membranous interventricular septum. The endocardial cushions separate the atria and ventricles.
16
Q
Where do you most commonly see VSD?
A
In the membranous interventricular septum. This is where the remnant of the interventricular foramen was.
17
Q
Where do the valves come from
A
They come from the endocardial cushions, all of them.
18
Q
Know the order in which fetal hematopoesis takes place
A
Young Liver Synthesizes Blood Yolk Sac (3-8 Weeks) Liver (6 weeks-birth) Spleen (10-28 weeks) Bone marrow (18 weeks to adult)
19
Q
What makes up fetal hemoglobin
A
HbF, alpha2gamma2
20
Q
What makes up adult hemoglobin
A
HbA, alpha2beta2
21
Q
Why does HbF more avidly bind O2 than HbA
A
it doesn’t bind 2,3-BPG as well
22
Q
What is delta hemoglobin
A
Starts around week 30 and very slowly increases through all of adult life???????
23
Q
When does HbF switch to HbA
A
Immediately after birth is the crossing point.
24
Q
Know fetal circulation.
A
…………..
25
Why does ductus arteriosus close?
Placental separation leads to decreased prostaglandins which makes it close.
26
What affects ductus arteriosus opening/closure
```
Indomethacin closes (prostaglandin inhibitor)
Prostaglanin E1 and E2 keep it open.
```
27
PO2 of blood in umbilical vein
30 mmHg and is 80% saturated with O2
28
What remnant does the umbilical vein form?
Ligamentum teres herpatis (contained in falciform ligament)
29
What do umbilical arteries form remnant
MediaL umbilical ligaments
30
What remnant does Foramen ovale form?
Fossa ovalis
31
What remnant does AllaNtois form
Urcahus-mediaN umbilical ligamenet
32
What is the allantois?
The allantois becomes the urachus.
33
What is the urachus
The urachus is the part of the allantoic duct between the bladder and umbilicus. Urachal cyst or sinus is a remnant. The urachus removes urine from the fetal bladder.
34
What does notochord leave as a remnant
Nucleus pulposus
35
Thyroid development
Thyroid diverticulum arises from floor of primitive pharynx, descends into neck. Connected to tongue by thyroglossal duct, which normally disappears but may persist as pyramidal lobe of thyroid. Foramen cecum is normal remnant of thyroglossal duct.
36
Most common ectopic thyroid tissue site?
The tongue
37
Thyroglossal duct cyst presentation
Anterior midline neck mass that moves with swallowing or protrusion of the tongue (vs. persistent cervical sinus leading to branchial cleft cyst in the lateral neck)
38
Foregut forms what
Pharynx to duodenum
39
Midgut forms what
Duodenum to proximal 2/3 of transverse colon
40
Hindgut forms what
Distal 1/3 of transverse colon to anal canal above pectinate line.
41
Rostral fold closure of anterior abd. wall results in
Sternal defects
42
Lateral fold closure of ant. abd. wall results in
Omphalocele, gastroschisis
43
Caudal fold closure of ant. abd. wall results in
Bladder exstrophy
44
What causes duodenal atresia
Trisomy 21
45
What causes jejunal, ileal, and colonic atresia
Vascular accident (apple peel atresia)
46
Apple peel atresia????
?????????????
47
Midgut development: 6th and 10th weeks
6th week: midgut herniates through umbilical ring
| 10th week: returns to abd. cavity + rotates around SMA
48
What are the different types of tracheoesophageal fistula
Most common 85%: EA with distal TEF: Proximal esophagus atresia and distal esophagus connecting to trachea.
H-type: pure TEF
Pure EA: atresia or stenosis of esophagus
49
What does TEF present with
Drooling, choking, and vomiting with first feeding.
50
What causes cyanosis with TEF
secondary to laryngospasm to avoid reflux-related aspiration
51
Which TEF has a gasless abdomen
Pure esophageal atresia
52
Describe congenital pyloric stenosis
Olive mass in epigrastric region with nonbilious projectile vomiting at around 2-6 weeks old. Occurs in 1/600 live births, more often in firstborn males.
53
Pancreas derived from what
Foregut
54
What does ventral pancreatic bud form
Pancreatic head and main pancreatic duct.
55
What does dorsal pancreatic bud form
Body, tail, isthmus, and accessory pancreatic duct.
56
Annular pancreas path
Ventral pancreatic bud abnormally encircles 2nd part of duodenum forming ring of pancreatic tissue causing duodenal narrowing
57
Pancreas divisum path
ventral and dorsal parts fail to fuse at 8 weeks
58
Spleen origin
Arises in mesentery of stomach (hence mesodermal) but is supplied by foregut (celiac artery)
59
What are the three embroylogical kidneys
Pronephros
Mesonephros
Metanephros
60
Pronephros
Week 4; then degenerates
61
Mesonephros
Functions as interim kidney for 1st trimester; later contributes to male genital system
62
Metanephros
Permanent kidney; first appears in 5th week of gestation; nephrogenesis continues through 32-36 weeks of gestation
63
Urteric bud
Derived from caudal end of mesoneprhic duct; gives rise to ureter, pelvises, calyces, and collecting ducts; fully canalized by 10th week
64
Metanephric mesenchyme
Ureteric bud interacts with this tissue; interaction induces differentiation and formation of glomerulus through to distal convuluted tubule
65
What is the last thing to canalize in the renal system
The Ureteropelvic junction, most common site of obstrution (hydronephrosis in fetus)
66
Potter syndrome mnemonic
POTTER syndrome: Pulm. hypoplasia, Oligohydramnios (trigger), Twisted face, Twisted Skin, Extremity defects, Renal failure (in utero)
67
Facial anomalies of oligohydramnios (potter's)
low-set ears and retrognathia
68
Causes of Potter's
ARPKD, posterior urethral valves, bilateral renal agenesis
69
Where are the horseshoe kidneys
Lower set because the inferior poles hit the IMA while migrating up.
70
Horseshoe kidney sequelae
Increased risk for ureteropelvic junction obstruction, hydronephrosis, renal stones, and rarely renal cancer (Wilms tumor).
71
Horseshoe kidney associated with....
Turner syndrome
72
Multicystic dysplastic kidney cause
Abnormal interaction between ureteric bud and metanephric mesenchyme.
73
Multicystic dysplastic kidney path
Nonfunctional kidney consisting of cysts and connective tissue. if unilateral (most common), generally asx with compensatory hypertophy of contralateral kidney. Often diagnosed prenatally via u/s.
74
What are the stages of development of nervous system
Notochord signals for overlying ectoderm to differentiate into neruoectoderm and form the neural place. Neural plate gives rise to the neural tube and neural crest cells.
75
What components make up the spinal cord
```
Alar plate (dorsal): sensory
Basal plate (ventral): motor
```
76
How long does it take for neural plate to form neural tube
Between Day 18-21
77
What are the three primary vesicles of the brain
Prosencephalon, Mesencephalon, and Rhombencephalon
78
What does prosencephalon form
Telencephalon and diencephalon
79
What does mesencephalon form
Mesencephalon
80
What does rhombencephalon form
Metencephalon and myelencephalon
81
What does telencephalon and diencephalon form
Tel: is cerebral cortex and lateral ventricles
Di: is Thalamus and the third ventricle
82
What does mesencephalon form
Midbrain and aqueduct
83
What does metencephalon and myelencephalon form
Met: Pons and cerebellum and upper part of fourth ventricle
Myel: Medulla nad lower part of fourth ventricle
84
What forms PNS neurons and Schwann cells
Neural crest cells
85
What forms ependymal cells, oligodendroglia, and astrocytes
Neuroectoderm, along with the CNS neurons
86
What forms microglia
Mesoderm (like macrophages, which originate from Mesoderm)
87
What increases risk of Neural tube defects?
Low folate intake before conception and during pregnancy
88
Tests for NTDs
elevated alpha-fetoprotein in amniotic fluid and maternal serum. Increased AChE in amniotic fluid is a helpful confirmatory test (fetal AChE transudates across defect into amniotic fluid
89
What is the path of NTDs
Neuropores fail to fuse (4th week) leading to persistent connection between amniotic cavity and spinal canal
90
What are the three types of NTDs
Spina bifida occulta, meningocele, meningomyelocele
91
What is AFP in meningocele
Normal
92
What is AFP in meningomyelocele
??????????
93
Anencephaly presentation
Malformation of anterior neural tube resulting in no forebrain, open calvarium ("frog-like appearance"). Inc. AFP, polyhydramnios from absent swallowing center in brain.
94
Anencephaly associated with
Maternal diabetes Type I
95
What decreases risk for anencephaly
Maternal folate supplementation
96
Holoprosencephaly path
Failure of left and right hemispheres to separate, during weeks 5-6. Multifactorial that may be related to sonic hedgehog sinaling pathway.
97
Holoprosencephaly presentation
Moderate form has cleft lip/palate, most severe form results in cyclopia
98
What are the posterior fossa malformations
Chiari II (Arnold-Chiari malformation) and Dandy-Walker
99
Chiari II
Significant herniation of cerebellar tonsils and vermis through foramen magnum with aqueductal stenosis and hydrocephalus. Often presents with lumbosacral myelomeningocele and paralysis below the defect.
100
Dandy-Walker
Agenesis of cerebellar vermis with cystic enlargement of 4th ventricle (fills the enlarged posterior fossa). Associated with hydrocephalus and spina bifida
101
What is syringomyelia
Cystic cavity within the spinal cord which leads to damage to crossing anterior spinal commissural fibers that leads to cape like distribution of bilaterall loss of pain and temp sensation in upper extremities with fine touch sensation preserved.
102
What levels affected by syrinx
C8-T1
103
What is syringomyelia associated with
Chiari I malformation (>3-5 mm cerebellar tonsillar ectopia; congenital, usually asx in childhood, manifests with HA and cerebellar sxs)
104
What is hydromyelia
Cystic cavity in the central canal.
105
Tongue development
1st and 2nd branchial arches form anterior 2/3 (thus sensation via CN V3, taste via CN VII)
3rd and 4th branchial arches form posterior 1/3 (thus sensation and taste mainly via CN IX, extreme posterior via CN X)
Motor innervation is via CN XII
Muscles of tongue from occipital myotomes
106
What detects taste (neuro)
CN VII, IX, X (solitary nucleus)
107
What detects pain
CN V3, IX, X
