Embryology Flashcards
1
Q
Produced at apical ectodermal ridge. Necessary for proper organization along dorsal-ventral axis.
A
Wnt-7 protein
2
Q
What are the apical ectodermal ridges?
A
Areas of thickened ectoderm at the distal end of each developing limb.
3
Q
Produced at apical ectodermal ridge. Stimulates mitosis of underlying mesoderm, providing for lengthening of limbs.
A
FGF protein
4
Q
Involved in segmental organization of embryo in a craniocaudal direction. Code for transcription factors.
A
Homeobox (Hox) genes
5
Q
Hox mutations lead to…
A
Appendages in wrong locations
6
Q
hCG secretion begins around the time of…
A
Implantation of the blastocyst (remember: “it sticks at day 6”)
7
Q
Bilaminar disc consisting of the…and…appears within week…of fetal development.
A
Epiblast; hypoblast; 2
Remember: 2 weeks = 2 layers
8
Q
The trilaminar disc appears within week…of fetal development.
A
3
Remember: 3 weeks = 3 layers
9
Q
The neural tube is formed by…and closes by week…
A
Neuroectoderm; 4
10
Q
The embryonic period extends from weeks…
A
3-8
11
Q
The embryonic period is characterized by…and extreme susceptibility to…
A
Organogenesis; teratogens
12
Q
The heart begins to beat in week…
A
4
13
Q
The upper and lower limb buds begin to form in week…
A
4
Remember: 4 weeks = 4 limbs
14
Q
Fetal cardiac activity is visible by transvaginal ultrasound by week…
A
6
15
Q
Genitalia have male/female characteristics by week…
A
10
16
Q
Process that forms the trilaminar embryonic disc (i.e., establishes the ectoderm, mesoderm, and endoderm germ layers) is known as…
A
Gastrulation.
17
Q
Gastrulation begins with the…invaginating to form the…
A
Epiblast; primitive streak
18
Q
Surface ectoderm gives rise to which structures?
A
Epidermis; adenohypophysis (from Rathke pouch); lens of eye; epithelial linings of oral cavity, sensory organs of ear, and olfactory epithelium; anal canal below the pectinate line; parotid, sweat, and mammary glands
19
Q
Benign Rathke pouch tumor with cholesterol crystals, calcifications
A
Craniopharyngioma
20
Q
Neuroectoderm gives rise to which structures?
A
Brain (neurohypophysis, CNS neurons, oligodendrocytes, astrocytes, ependymal cells, pineal gland), retina and optic nerve, spinal cord
21
Q
Produced at base of limbs in zone of polarizing activity. Involved in patterning along anterior-posterior axis. Involved in CNS development; mutation can cause holoprosencephaly.
A
Sonic hedgehog protein
22
Q
Neural crest cells give rise to…
A
- PNS (dorsal root ganglia, cranial nerves, celiac ganglion, Schwann cells, ANS)
- Melanocytes
- Chromaffin cells of adrenal medulla
- Parafollicular (C) cells of thyroid
- Pia and arachnoid mater
- Bones of the skull
- Odontoblasts
- Aorticopulmonary septum
23
Q
Mesoderm gives rise to…
A
- Muscle
- Bone
- Connective tissue
- Serous linings of body cavities (e.g., peritoneum)
- Spleen (derived from foregut mesentery)
- Cardiovascular structures
- Lymphatics
- Blood
- Wall of gut tube
- Vagina
- Kidneys
- Adrenal cortex
- Dermis
- Testes
- Ovaries
24
Q
Notochord induces…to form…
A
Ectoderm; neuroectoderm (neural plate)
25
The only postnatal derivative of the notochord is the...
Nucleus pulposus of the intervertebral disc.
26
VACTERL is a syndrome characterized by...
1. Vertebral defects
2. Anal atresia
3. Cardiac defects
4. Tracheoesophageal fistula
5. Renal defects
6. Limb defects (bone and muscle)
27
Endoderm gives rise to...
1. Gut tube epithelium (including anal canal above the pectinate line)
2. Most of urethra (derived from urogenital sinus)
3. Luminal epithelial derivatives (e.g., lungs, liver, gallbladder, pancreas, Eustachian tube, thymus, parathyroid, thyroid follicular cells)
28
Absent organ due to absent primordial tissue.
Agenesis
29
Absent organ despite presence of primordial tissue
Aplasia
30
Incomplete organ development; primordial tissue present
Hypoplasia
31
Extrinsic disruption; occurs after embryonic period
Deformation
32
Secondary breakdown of previously normal tissue or structure (e.g., amniotic band syndrome)
Disruption
33
Intrinsic disruption; occurs during embryonic period (weeks 3-8)
Malformation
34
Abnormalities result from a single primary embryologic event
Sequence (e.g., oligohydramnios --> Potter sequence)
35
Effect of ACE inhibitors on fetus
Renal damage
36
Effect of alkylating agents on fetus
Absence of digits, multiple anomalies
37
Effect of aminoglycosides on fetus
CN VIII toxicity
Remember: A mean guy hit the baby in the ear.
38
Effect of carbamazepine on fetus
Facial dysmorphism, developmental delay, neural tube defects, phalanx/fingernail hypoplasia
39
Effect of diethylstilbestrol (DES) on fetus
Vaginal clear cell adenocarcinoma, congenital Mullerian anomalies
40
Effect of folate antagonists on fetus
Neural tube defects
41
Effect of isotretinoin on fetus
Multiple severe birth defects
42
Effect of lithium on fetus
Ebstein anomaly (atrialized right ventricle)
43
Effect of methimazole on fetus
Aplasia cutis congenita
44
Effect of phenytoin on fetus
Fetal hydantoin syndrome -- cleft palate, cardiac defects, phalanx/fingernail hypoplasia
45
Effect of tetracyclines on fetus
Discolored teeth
46
Effect of thalidomide on fetus
Limb defects (phocomelia, micromelia -- "flipper" limbs)
47
Effect of valproate on fetus
Inhibition of maternal folate absorption --> neural tube defects
48
Effect of warfarin on fetus
Bone deformities, fetal hemorrhage, abortion, ophthalmologic abnormalities
Remember: Do not wage warfare on the baby; keep it heppy with heparin (does not cross placenta).
49
Effect of alcohol on fetus
Common cause of birth defects and intellectual disability; fetal alcohol syndrome
50
Effect of cocaine on fetus
Abnormal fetal growth and fetal addiction; placental abruption
51
Effect of maternal smoking on fetus
Low birth weight (leading cause in developed countries), preterm labor, placental problems, IUGR, ADHD
Nicotine --> vasoconstriction
Carbon monoxide --> impaired O2 delivery
52
Effect of iodine excess or deficiency on fetus
Congenital goiter or hypothyroidism (cretinism)
53
Effect of maternal diabetes on fetus
Caudal regression syndrome (anal atresia to sirenomelia), congenital heart defects, neural tube defects
54
Effect of excess vitamin A on fetus
Extremely high risk for spontaneous abortions and birth defects (cleft palate, cardiac anomalies)
55
Effect of X-rays on fetus
Microcephaly, intellectual disability
56
Leading cause of intellectual disability in the U.S.
Fetal alcohol syndrome
57
Newborns of alcohol-consuming mothers exhibit increased incidence of congenital abnormalities, including...
1. Pre- and postnatal developmental retardation
2. Microcephaly
3. Facial abnormalities (e.g., smooth philtrum, hypertelorism)
4. Limb dislocation
5. Heart defects
6. Holoprosencephaly in most severe form
58
Dizygotic twins arise from...
2 eggs that are separately fertilized by 2 different sperm and will have 2 separate amniotic sacs and 2 separate placentas (chorions).
59
Monozygotic twins arise from...
1 fertilized egg (1 egg + 1 sperm) that splits into 2 zygotes in early pregnancy.
60
The degree of separation between monozygotic twins depends on...
When the fertilized egg splits into 2 zygotes. The timing of this separation determines the number of chorions and the number of amnions.
61
Inner layer of chorionic villi
Cytotrophoblast
62
Outer layer of chorionic villi; secretes hCG
Syncytiotrophoblast
63
hCG is structurally similar to which other hormone?
LH
64
What is the function of hCG?
Stimulates corpus luteum to secrete progesterone during first trimester
65
What is unique about the syncytiotrophlast that decreases the likelihood it is attacked by the maternal immune system?
Lacks MHC class I expression
66
The decidua basalis is the...component of the placenta and is derived from...
Maternal; endometrium
67
The umbilical arteries (there are 2) return deoxygenated blood from the fetal...to the...
Internal iliac arteries; placenta
68
The umbilical vein supplies oxygenated blood from the placenta to the fetus; it drains into the...via the liver or via the...
Inferior vena cava; ductus venosus
69
The umbilical arteries and vein are derived from...
The allantois.
70
A single umbilical artery (i.e., a 2-vessel cord) is associated with...
Congenital and chromosomal anomalies
71
In the...week of embryologic development, the yolk sac forms the..., which extends into the urogenital sinus.
3rd; allantois
72
The allantois becomes the..., a duct between the...
Urachus; fetal bladder and yolk sac
73
Total failure of the urachus to obliterate results in a...
Patent urachus, which manifests as urine discharge from the umbilicus
74
Partial failure of the urachus to obliterate results in a...
Urachal cyst, which is a fluid-filled cavity lined with uroepithelium between the umbilicus and bladder
75
Complications associated with urachal cysts include...
Infection and adenocarcinoma.
76
Slight failure of the urachus to obliterate results in an outpouching of the bladder known as a...
Vesicourachal diverticulum.
77
The vitelline duct is also known as the..., which connects the yolk sac to the...
Omphalomesenteric duct; midgut lumen
78
At which point during embryologic development does the vitelline duct normally obliterate?
During the 7th week.
79
If the vitelline duct fails to close, a...is formed, manifesting postnatally as...
Vitelline fistula; meconium discharge from the umbilicus
80
Partial closure of the vitelline duct with a patent portion attached to the ileum (i.e., a true diverticulum) is known as a...
Meckel diverticulum
81
Meckel diverticula may contain heterotopic...
Gastric and/or pancreatic tissue
82
How does a Meckel diverticulum usually present?
With melena, hematochezia, abdominal pain
83
The 1st aortic arch develops into the...
Part of maxillary artery (branch of external carotid).
Remember: The 1st arch is maximal.
84
The 2nd aortic arch develops into the...
Stapedial artery and hyoid artery.
Remember: The Second arch is Stapedial.
85
The 3rd aortic arch gives rise to the...
Common carotid artery and proximal part of internal carotid artery.
Remember: C is the 3rd letter of the alphabet.
86
The 4th aortic arch gives rise to...
The aortic arch on the left and the proximal part of the right subclavian artery on the right.
87
The 6th aortic arch gives rise to...
The proximal part of the pulmonary arteries and (on the left only) the ductus arteriosus.
88
Branchial clefts (also called branchial grooves) are derived from...
Ectoderm
89
Branchial arches are derived from...and...
Mesoderm (muscle, arteries); neural crest cells (bones, cartilage)
90
Branchial pouches are derived from...
Endoderm
91
1st branchial cleft develops into...
External auditory meatus
92
2nd through 4th clefts form...that are eventually obliterated by...
Temporary cervical sinuses; proliferation of 2nd arch mesenchyme
93
Persistence of cervical sinuses manifests as...
Branchial cleft cysts within lateral neck.
94
The 1st branchial arch gives rise to...
1) Meckel cartilage: mandible, malleus, incus, sphenomandibular ligament
2) Muscles of mastication (temporalis, masseter, lateral and medial pterygoids), mylohyoid, anterior belly of digastric, tensor tympani, tensor veil palatini
3) CN V2 and V3
95
Treacher Collins syndrome results from...
Failed migration of neural crest cells of 1st branchial arch; result is mandibular hypoplasia and facial abnormalities
96
The 2nd branchial arch gives rise to...
1) Reichert cartilage: Stapes, Styloid process, lesser horn of hyoid, Stylohyoid ligament
2) Muscles of facial expression, Stapedius, Stylohyoid, platySma, posterior belly of digastric
3) CN VII (facial expression)
97
Persistence of the 2nd branchial cleft and pouch produces a fistula between the tonsillar area and lateral neck known as a...
Congenital pharyngocutaneous fistula
98
The 3rd branchial arch gives rise to...
1) Greater horn of hyoid
2) Stylopharyngeus
3) CN IX
99
The 4th and 6th branchial arches give rise to...
1) The cartilages of the larynx (thyroid, cricoid, arytenoids, corniculate, cuneiform)
2) 4th arch gives rise to most pharyngeal constrictors, cricothyroid, levator veli palatini; 6th arch gives rise to all intrinsic muscles of the larynx, except the cricothyroid
3) 4th arch gives rise to superior laryngeal branch of CN X; 6th arch gives rise to recurrent laryngeal branch of CN X
100
The posterior 1/3 of the tongue is formed from...
Arches 3 and 4
101
The 1st branchial pouch develops into...
The middle ear cavity, Eustachian tube, mastoid air cells
102
The 2nd branchial pouch develops into...
The epithelial lining of the palatine tonsil.
103
The dorsal wings of the 3rd branchial pouch develop into...
The inferior parathyroid glands.
104
The ventral wings of the 3rd branchial pouch develop into...
The thymus.
105
3rd-pouch structures end up...4th-pouch structures.
Below
106
The dorsal wings of the 4th branchial pouch develop into the...
Superior parathyroid glands.
107
Aberrant development of the 3rd and 4th pouches results in...
DiGeorge syndrome
108
DiGeorge syndrome is characterized by...
T-cell deficiency (due to thymic aplasia) and hypocalcemia (due to failure of parathyroid development)
109
DiGeorge syndrome is associated with which type of cardiac defects?
Conotruncal anomalies
110
In MEN 2A, germline mutations in...affect...
RET; neural crest cells
111
MEN 2A affects...
1. Adrenal medulla (pheochromocytoma)
2. Parathyroid (tumor)
3. Parafollicular cells of thyroid (medullary thyroid cancer)
Remember: Parafollicular cells are derived from neural crest cells associated with the 4th branchial pouches.
112
Failure of fusion of the maxillary and medial nasal processes (i.e., formation of the primary palate) produces...
Cleft lip
113
Cleft palate results from...
Failure of fusion of the two lateral palatine processes or failure of fusion of the lateral palatine processes with the nasal septum and/or median palatine process (i.e., formation of secondary palate)
