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23 Cards in this Set

  • Front
  • Back
1)repression of sets of genes

2) w/in responsive cells

2) competence
-regulation of a gene activity w/out changing the genetic structure
Growth during embryonic period is due to these 3 types of growth
-hyperplasia: increase in cell #
-hypertrophy: increase in cell size
-increase in ECM
congenital malformations
-abnormalities arising during prenatal development
3 principles important to understanding the etiology of congenital malformation
-critical periods of development
-severity of the environmental insult
-genotype of individual
responsible for the ability of an organ to perform its adult function
-fertilized ovum than has not yet implanted in uterus (day 6)
embryonic period
-week 2-8
-with devp't of embryonic disk
fetal period
-week 9-birth
-growth and maturation of basic organ systems
3 stages of prenatal devp't
-zygote (0-6days)
-embryonic period (W2-8)
-fetal period (W9-birth)
prochordal plate (3)
-thickening, earliest indication of oral cavity
-appears end of 2nd week
-later becomes buccopharyngeal membrane
3rd Week (2)
-primitive streak forms
-ectoderm, endoderm, mesoderm are formed
primitive node (3)
-(Hensen's node)
-proliferation of cells at anterior end of primitive streak
-here mesoderm forms mesenchyme
-the mesoderm fits between the ectoderm and endoderm (except for in cloacal membrade and buccopharyngeal membrane)
two regions where gastrulation does not occure
-cloacal membrane (post)
-buccopharyngeal membrane (ant)
notochord (2)
-primitive axial skeleton
-induces overlying ectoderm to form neural plate
Changes to neural plate late in 3rd week (3)
-it invaginates, forming neural groove and neural folds (edges)
-segments into 4 sections: prosencephalon (forebrain), mesencephalon (midbrain), rhombencephalon (hindbrain), spinal cord w/ associated somites
-neural folds begin to fuse, from rhombencephalon both ant and post. (Last to fuse is ant neuropore and post neuropore)
______________ causes the future orofacial region into a more adult anatomical orientation and establishes position of ______________
-cephalic flexure: folding of head region

-stomodeum: primitive oral cavity
The prochordal plate becomes the ___________ and due cephalic flexure lies between the ___________ and the ___________
-buccopharyngeal membrane
-stomodeum (ectodermally-lined)
-foregut (endodermally-lined)
ectomesenchyme (3)
-fourth embryonic tissue
-arises from neural crest cells (from edges of neural folds)
-of ectodermal origin, but act like mesoderm)
Failure of ______________ to proliferate and/or differentiate is a major cause of congenital malformations affecting the orofacial region
neural crest cells
neural crest cells are highly ____________.

They become (4)

-chromaffin cells (adrenal medulla)
-ganglion cells of autonomic and sensory nerves
-arachnoid and pia mater
Time line:
Week 1 (2)
Week 2 (2)
Week 3 (4)
Week 4 (2)
Week 5-9
1: fertilization (finishing of meiosis II)
-becomes morula, then blastocyte

2: implantation
-bilaminar disc

3: gastrulation
-oral membrane
-3D folding occurs (into 4th week)

4: tooth, face formation

5-9: primary, secondary palate
How do branchial arches differentiate?
Because the cells that migrated down from the neural folds to form the branchial arches are specific