Embryology 1 (TQ)

poxidicu's version from 2016-03-25 13:20

Important Genes of Embryogenesis

Question Answer
SHH gene + locationProduced at base of limbs in zone of polarizing activity. Involved in patterning along anterior- posterior axis.
Involved in CNS development; mutation can cause holoprosencephaly
Wnt-7 gene +locationProduced at apical ectodermal ridge (thickened ectoderm at distal end of each developing limb).
Necessary for proper organization along dorsal-ventral axis.
FGF gene +locationProduced at apical ectodermal ridge.
Stimulates mitosis of underlying mesoderm, providing for lengthening of limbs.
Homeobox (Hox) gene + locationInvolved in segmental organization of embryo in a craniocaudal direction.
Hox mutationsŽ appendages in wrong locations.
SHH mutations?Holoprosencephaly
Hox mutations?Appendages in wrong locations
Wha tis the apical edermal ridge?Thickened ectoderm at distal end of each developing limb

Early Fetal Development

Question Answer
DAY 0Fertilization by sperm, forming zygote, initiating embryogenesis.
WITHIN WEEK 1hCG secretion begins around the time of implantation of blastocyst.
WITHIN WEEK 2Bilaminar disc (epiblast, hypoblast)
- epiblast becomes all future cells
2 weeks = 2 layers
WITHIN WEEK 3Gastrulation. → Trilaminar disc. 3 weeks = 3 layers
Primitive streak, notochord, mesoderm and its organization, and neural plate begin to form
- all layers come from the ectoderem
WEEKS 3–8 (Embryonic Period)Neural tube formed by neuroectoderm and closes by week 4
Extremely susceptible to teratogens.
WEEK 4Heart begins to beat
Upper and lower limb buds begin to form
4 weeks = 4 limbs
WEEK 6Fetal cardiac activity visible by transvaginal ultrasound.
WEEK 10Genitalia have male/female characteristics
When is most susceptible to teratogens?Week 3-8 (organogenesis)
Zygote progression (4, Mn)Day 0 = Fertilization
Day 2 = Zygote
Day 3 = Morula
Day 4 = Blastocyst
Day 7-10 = implantation in uterine wall
Fuck Zeus's Maiden Bitch
What is gastrulation? When does it start?Process that forms the trilaminar embryonic disc.
Establishes the ectoderm, mesoderm, and endoderm germ layers. Starts with the epiblast invaginating to form the primitive streak (week 3)


Question Answer
epidermissurface ectoderm
hairsurface ectoderm
nailssurface ectoderm
parotid, sweat, and mammary glandssurface ectoderm
Adenohypophysissurface ectoderm
enamel of teethsurface ectoderm
lens of the eyesurface ectoderm
epithelial linings of oral cavitysurface ectoderm
anal canal below the pectinate linesurface ectoderm
olfactory epitheliumsurface ectoderm
sensory organs of earsurface ectoderm
Brain (neurohypophysis, CNS neurons, oligodendrocytes, astrocytes, ependymal cells, pineal gland)Neuroectoderm
Retina and optic nerveNeuroectoderm
Spinal CordNeuroectoderm
All ganglia (PNS)Neuroectoderm
PNS (dorsal root ganglia, cranial nerves, celiac ganglion, Schwann cells, ANS)Neural crest
Meninges (pia+arachnoid)Neural crest
MelanocytesNeural crest
Odontoblasts (tooth enamel)Neural crest
Endocardial cushionNeural crest
smooth muscle of the eye and optic nervesNeural crest
Chromaffin cells of adrenal medullaNeural crest
Aorticopulmonary septumNeural crest
Bones of the skullNeural crest
Parafollicular cells of thyroidNeural crest (MEN2A)
- produces calcitonin

Mesoderm and Endoderm

Question Answer
Bone + connective tissueMesoderm
Serous linings of body cavities (ie peritoneum)Mesoderm
Cardiovascular structuresMesoderm
Wall of gut tubeMesoderm
KidneysMesoderm (1' retroperitoneal)
Adrenal cortexMesoderm
Testes and ovariesMesoderm
Notochord. What does it become?Mesoderm → induces ectoderm to form neuroectoderm
Becomes nucleus pulposus (center) of the intervertebral disc.
Gut tube epitheliumEndoderm
Anal canal above pectinateEndoderm
Luminal epithelial derivativesEndoderm
Liver, pancreas, gallbladderEndoderm
Thymus, parathyroid, and thyroid follicular cellsEndoderm
Eustachian tubeEndoderm
List mesodermal defects (7)Mesodermal defects = VACTERL
Vertebral defects
Anal atresia
Cardiac defects
Tracheo-Esophageal fistula
Renal defects
Limb defects (bone and muscle)

Errors in organ morphogenesis

Question Answer
AgenesisAbsent organ due to absent primordial tissue.
AplasiaAbsent organ despite presence of primordial tissue.
HypoplasiaIncomplete organ development; primordial tissue present.
DeformationExtrinsic disruption; occurs after the embryonic period.
Disruption2° breakdown of a previously normal tissue or structure (e.g., amniotic band syndrome).
MalformationIntrinsic disruption; occurs during the embryonic period (weeks 3–8).
SequenceAbnormalities result from a single 1° embryological event (e.g., oligohydramnios Ž Potter sequence).


Question Answer
ACE inhibitorsRenal damage
Alkylating agentsAbsence of digits, multiple anomalies
AminoglycosidesCN VIII toxicity
A mean guy hit the baby in the ear
CarbamazepineNeural tube defects, craniofacial defects, fingernail hypoplasia, developmental delay, IUGR
Diethylstilbestrol (DES) (2)Vaginal clear cell adenocarcinoma, congenital Müllerian anomalies
Folate antagonistsNeural tube defects
LithiumEbstein anomaly (atrialized right ventricle)
MethimazoleAplasia cutis congenita
Phenytoin (5)Fetal hydantoin syndrome:
- microcephaly, dysmorphic craniofacial features
- hypoplastic nails and distal phalanges
- cardiac defects
- IUGR, intellectual disability
TetracyclinesDiscolored teeth “Teethracyclines”
ThalidomideLimb defects (phocomelia, micromelia— “flipper” limbs)
Limb defects with “tha-limb-domide.”
ValproateInhibition of maternal folate absorption Ž neural tube defects
ValproATE inhibits folATE absorption
Warfarin (4)Bone deformities, fetal hemorrhage, abortion, ophthalmologic abnormalities
Do not wage warfare on the baby; keep it heppy with heparin (does not cross placenta)
Iodine deficiency/excessCongenital goiter or hypothyroidism (cretinism)
Maternal diabetes (3)Caudal regression syndrome (anal atresia to sirenomelia)
congenital heart defects
neural tube defects
Vitamin A excess (3)Extremely high risk for spontaneous abortions
Birth defects (cleft palate, cardiac abnormalities)
X-rays (2)Microcephaly, intellectual disability
When are fetus most susceptible to teratogens?Week 3-8 (oragnogenesis)
Effect before week 3?All-or-none effect
Effect after week 8?Growth and function affected

Substance Abuse

Question Answer
Alcohol (2)Common cause of birth defects and intellectual disability (fetal alcohol syndrome)
Cocaine (3)Abnormal fetal growth and fetal addiction; placental abruption
Smoking (nicotine, CO) (4)A leading cause of low birth weight in developed countries;
- preterm labor, placental problems, IUGR, ADHD


Question Answer Column 3 Column 4
Lynch SyndromeMSH2,MLH1,MSH6,PMS2Colorectal cancer, Endometrial Cancer, OvarianNo Polyps
Familial adenomatous polyposisAPCColorectal, Desmoids, Osteomas, BrainAdenomatous polyps from normal colon
VHLVHLHemangioblastomas, Clear cell renal carcinoma, PheochromocytomaInactivating mutation
LiFraumeniP53Sarcomas, Breast, Brain, Adrenocortical, LeukemiaInactivating mutation
Men Type 1Parathyroid, Pituitary, PancreaticInactivating mutation
Men Type 2Meduallary thyroid, Pheochromocytoma, Pancreatic, ParathyroidActivating mutation


Question Answer
Anti-Psueodomnal PenicillinsTicarcillin, Piperacillin
CephalosporinsCeftazidime(3rd), Cefepime(4th)
AminoglycosidesAmikacin, Gentamicin, Tobramycin
FluoroquinolonesCiprofloxacin, Levofloxacin
CarabpenemsImipenem, Meropenem


Question Answer
CMVCellular Integrins
RabiesNicotinic Acetycholine receptors
RhinovirusICAM1 (CD54)


Question Answer Column 3
Ciliated Pseudostratified columnarNasal cavity, upper pharynx, false vocal cords, trachea, bronchi- Mucus secreting cells moisten air & trap debris, Sweeps debris toward pharynx for swallowing
Squamous StratifiedTrue vocal cordsProtects abrasion & chemical attack
Cuboidal: BronchiolesConduct air to alveoli
Simple SquamousAlveoliGas exchange


Question Answer Column 3 Column 4 Column 5
Partial MoleBenignFocally Hyperplastic TrophoblastsVilli focally enlargedFetal tissue present/Triploid
Complete MoleBenignDiffusely Hyperplastic TrophoblastsVilli diffusely enlargedAbsent
Invasive MoleMalignantTrophoblasts Diffusely hyperplastic with myometrial invasionVilli diffusely enlargedAbsent
ChoriocarcinomaMalignantTrophoblasts diffusely anaplastic with necrotic vascular invasion(Lungs)Absent villiPresent or Absent


Question Answer
VirulenceEvasion against host immune
S.AureusProtein A
S.PneumoniaIgA protease
H.InfluenzaIgA protease
NeisseriaIgA protease
Group A StreptococcoiM Protein

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