Embryology 1 - Overview and Teratology Flashcards
When is the Embryonic Period?
fertilization –> second month of gestation
When is the Fetal Period?
Second month of gestation –> full term
What is the Obstetric (gestational ) age?
Begins at last menstrual period
What is the Embryonic age?
Begins at time of fertilization
What is Fertilization?
- Initiation of embryo development
- Occurs when an oocyte and sperm merge
During 1st week, embryo is ____
Preparing for implantation
Within 2 days of fertilization, a ______ has formed.
Zona pellucida
At around 5 days, a ____ hatches out of the zona pellucida
Blastocyst
During 2nd-3rd weeks, embryo is _____.
Setting up basic body plan
At around 6-7 days, _____ occurs
Implantation
At around 16 days, the embryo develops _______ and is ___ long.
Primitive streak at the caudal end; 1 mm
At around 22 days, the embryo develops _____ and is __ long.
Somites (body segmentation); 2.5mm
During the 4th-8th weeks, the embryo is ______.
Making precursors of major organs.
During the 4th week, the embryo has developed _____ and is ___ long.
4 mm.
During the 5th week, the embryo has developed ____.
During 7th week, the embryo has begun developing _______and is __ long.
During 9th-38th weeks, embryo is undergoing _____.
Growth and organ development
During 9th week, ____ is unclear. Embryo is ___long and weighs ____.
During 18th week, fetus has _____, is __ long and weighs __.
During 7th month, fetus is __long and weighs __.
What are the Events of Parturition (Birth) (3)
1) Rupture of amniochorionic membrane
2) Effacement and dilation of the cervix
3) Delivery by contraction of uterus and abdominal muscles
What is Malformation?
Formation of a structure fails, resulting in its absence or alteration of configuration
What is Disruption?
Destructive event alters morphology of a structure that has already formed
What is Deformation?
Aberrant mechanical forces mold a structure and cause deformation
What is the Period of greatest susceptibility to teratogen exposure?
3rd-8th weeks
What is the most common teratogen?
Alcohol
What are the symptoms of Fetal Alcohol Syndrome?
Heart defects, growth retardation, neurodevelopmental abnormalities, distinct facial features
What is Thalidomide? What does it cause?
- Oral sedative for pregnant women in late 1950s
- Caused distinct limb malformation, and facial, kidney, cardiac, anal, neurological, and growth defects
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What are the effects of Vitamin A as a Teratogen?
- Excessive use of vitamin A may cause birth defects
- Vitamin A plays essential roles in body patterning during embryogenesis
What are the effects of Rubella (German Measles) as a Teratogen?
- When mother is infected during first trimester:
- deafness
- cataract, glaucoma
- heart defect
- mental retardation
What are some Infectious Agent Teratogens (5)?
- Rubella (German Measles
- Toxoplasmosis
- Syphilis
- Varicella virus
- Cytomegalovirus
What are some Physical Agent Teratogens (2)?
- X-rays
- Hyperthermia
What are some Maternal Condition Teratogens (2)?
- Diabetes
- Obesity
What are some Drug Teratogens (8)?
- Amphetamine (psychostimulant)
- Phenytoin (antiepileptic)
- Valproic acid (anticonvulsant)
- Lithium (treat bipolar disorder)
- SSRI (antidepressant)
- Warfarin (anticoagulant)
- ACE inhibitor (treat hypertension)
- Mycophenolate mofetil (immunosuppressant)
What is the definition of a Syndrome?
Several clinically recognizable features, signs or symptoms that occur together due to an underlying cause
What is Holt-Oram Syndrome?
- Genetic disorder that impairs upper limbs and heart
- Due to TBX5 mutation
What is TBX5?
Transcription factor expressed in upper limb buds and heart precursor durying embryogenesis and plays essential role in their formation
What is DiGeorge Syndrome?
- Genetic disorder that causes hearing loss, cleft palate, heart defects, and/or other anomalies
- Caused by small deletion in chromosome 22
- Impairs neural crest differentiation and migration
What is Kartagener Syndrome?
- Genetic disorder that results in chronic sinusitis, bronchitis, infertility, and/or situs inversus
- Mutation in left-right dynein (LRD) gene causes defects in cilum functions
