Devo - Lecture 5 Embryogenesis Organogenesis
Terms
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- What is neurulation?
- formation of CNS
- Initial CNS primordia
- Neural plate
- Neural plate comes from
- ectoderm
- Notochord comes from
- mesoderm
- What tells the ectoderm to thicken into neural plate?
- notochord
- The neural plate becomes
- Neural tube - it bends into it.
- Where is intraembryonic mesoderm
- on either side of notochord; between endoderm and ectoderm
- the 3 layers of intraembryonic mesoderm on either side of notochord are:
-
-paraxial mesoderm
-intermed. mesoderm
-lateral mesoderm - paraxial mesoderm becomes
-
SOMITES:
-skull
-skeletal muscles
-fibrous ct
-dermis - intermediate mesoderm becomes
-
-kidneys
-ureters
-gonads
-reproductive ducts
-adrenal cortex - where does the notochord lie in all this?
- Axial mesoderm
- What is the first step in paraxial mesoderm development?
- Segmentation into somites
- what are somites?
- Temporary - allow further segregation of precursor cells.
- What do the somites develop into?
-
-Scleratome
-Dermomyotome - Birth defects cause how many deaths
- 20%
-
Major birth defects are detected in how many infants
-at birth
-in childhood -
birth = 1-2%
childhood = 4-6 -
advanced age is risk factor for:
-maternal
-paternal -
maternal = downs
paternal = achondroplasia, apert's - Season of the year is associated with increased risk of:
- anencephaly in infants conceived in ireland in spring months
- country of residence is associated with
-
-increased anencephaly in celtic population
-thalidomide problems in europe where drug was sold - race is associated with what birth defects
-
-cleft palate - 2 x more commin in whites than blacks
-doesn't influence rate - polycdactyly is commin
- amish
- when does a defect occur?
- Emryonic period
- when do disruptions occur
- embyronic-fetal period
- when do deformations occur?
- late in fetal period
- what is a defect?
- morphological malformation resulting from abnormal developmental mechanisms or processes - intrinsic, can be inherited.
- what is a disruption?
- morpholog malformation resulting from a breakdown or interference with an ORIGINALLY NORMAL developmntl process.
- are disruptions intrinsic or ex?
- Extrinsic - can be made more susceptible to it by genetics tho.
- what is deformation?
- abnormality caused by nondisruptive mechanical force
- what is a polytrophic field affect?
- pattern of anomalies in a disturbed single field i.e. whole organ or body area.
- what is a syndrome?
- pattern of multiple primary anomalies seen together and causally related
- what is a sequence?
- pattern/cascade of 2' anomalies that result from a single primary anomaly or initiator
- what is an association?
- a nonrandom occurence of 2/more features, occur more often than expected by chance alone, idiopathic.
- causes of abnormal development:
-
genetics
environment
multifactorial - what are 2 types of genetic factors?
-
-chromosome problems
-gene mutations - 2 ways chromsm's can be abnormal
-
-number - aneuploidy/polyploidy
-structure - what is aneuploidy?
- ch' number is not exact multiple of hyploid number
- what is polyploidy?
- ch' number is exact multiple of haploid number - eg triploid
- what is a dominant mutation vs. recessive?
- recessive requires a double dose of gene mutation, dom only one
- what is a teratogen
- agent that can produce congeital anomaly or raise incidence of anomaly
- what is teratology?
- dysmorphogenesis - study of birth defects
- what is worse; acute or chronic drug use?
- chronic
- What causes 20-25% of all birth defects?
- multifactorial effects
- What do multifactorial effects result from?
-
interaction of
-Genetic endowment
-developmental environmetn - What is the cause of most birth defects?
- UNKNOWN
- Give an example of anomalies caused by the following developmental disturbances:
- ok
- Duplications and reversal of assymetry:
- conjoined twins, situs inversus
- Faulty inductive interactions
- complete or partial absence of structures
- absenc of normal cell death
- webbed dgiits
- failure of fusion or merging
- facial clefting
- disturbances in tissue resorption
- duodenal or anal atresia
- failure of migration
- ectopic kidney
- developmental arrest
- cleft palat, thyroglossal duct cyst
- hyperplasia and hypoplasia
- overgrowth or undergrowth
- defective fields
- caudal regression
- failure of tube formation
- neural tube defects
- destruction of formed structures
- unilateral distortion of the face
- receptor defects
- achondroplasia
- germ layer defects
- ectodermal dysplasias
- secondary effects
- cyclopia
-
First five A-list teratogens:
ABCCD -
Antianxiety
Antibiotics
Anticonvulsants
Anticoagulants
Androgens -
Last A list teratogens
H-NNOP -
Antihypertensive
Antinauscants
Antineoplastics
Alcohol
Antipsychotic