embryo Flashcards
5 ____ develop as bulging prominences around the ____ during week 4
facial primordia; stomodeum
5 different primordia include:
frontonasal prominence (rostral to stomodeum) maxillary prominences (lateral to stomodeum) mandibular prominences (caudal to stomodeum)
____ separates the primitive oral cavity from the developing GI tract and disintegrates during the early 5th week
buccopharyngeal membrane
most facial structures develop during weeks ____ which is during the _____
4-8 (2nd month); embryonic period
during fetal period, ___ expands to accompany the growing brain, which causes the eyes to shift ____
cranium; anteriorly and medially
during the fetal period, the ____ move superiorly and the ___ becomes more prominent
ears; nose
proportions of the facial skeleton become more normal once the _____ grow and once fetus acquires ____
maxilla and mandible grow (to allow space for teeth)
paranasal sinuses
at the end of the 4th week, 2 ____ thickenings develop within the frontonasal prominence, called the _____
ectodermal; nasal placodes
____ surrounding the placodes proliferates, forming elevations called:
mesenchyme
medial and lateral nasal prominences (2 of each)
during the 5th week, epithelium of nasal placodes sinks down into underlying mesenchyme to form depressions called ____, which will become the future ____
nasal pits; nostrils (nares)
the nasal pits will deepen and expand dorsally to form ____, which will form the ____
nasal sacs; right and left nasal cavities
____ separates nasal cavities from oral cavity; ruptures at the end of week 6
oronasal membrane
after rupture of oronasal membrane, nasal and oral cavities are now in communication through ____
primordial choanae
development of the ____ establishes the definitive choanae, separating the ____
secondary palate ; nasal cavity from nasopharynx
____ gives rise to olfactory epithelium
neuroectoderm
____ develop from lateral walls of the nasal cavity
nasal conchae
____ prominences fuse at the midline first to create a smooth jawline
mandibular
maxillary prominences grow in size and move medially, compressing the ____ in the midline, causing them to fuse
medial nasal prominences
cleft between lateral nasal prominences and maxillary prominences is the _____; it is lost once the prominences fuse
nasolacrimal groove
____ proliferates into underlying ____ and forms a solid rod that separates from the surface and canalizes to become the ____
ectoderm; mesenchyme; nasolacrimal duct
superior end of nasolacrimal duct dilates to form ____ and inferior end opens up into _____
nasolacrimal sac; inferior meatus of the nasal cavity
medial nasal prominences fuse to form the ____
intermaxillary segment
intermaxillary segment consists of:
- philtrum of upper lip (labial component)
- premaxillary part of maxilla (upper jaw comp); 4 incisors and assoc gingiva
- primary palate (palatal comp; the primary hard palate is only the most anterior portion of the hard palate)
secondary palate is composed of:
remainder of hard palate + soft palate + uvula
during week 6, two plates of mesenchyme, _____, extend medially from the maxillary prominences
lateral palatine processes
palatine processes project ____, then swing upwards to assume ____ position, and fuse with ____, ____, and ____
inferomedially ; horizontal; each other, primary palate, and nasal septum
____ marks where secondary palate fuses with primary palate and is used to indicate ant and post palatal defects
incisive foramen
____ marks where lateral palatine processes fused together
median palatine raphe
____ and ____ will ossify forming the bony hard palate
primary palate; anterior portion of secondary palate
cleft lip (with or without cleft palate) is an ____ palatal defect caused by failure of :
anterior; medial nasal prominences to fuse with maxillary prominences on one or both sides
during week 4, the inner ear is the first to develop as a bilateral thickening in ____ at the level of the ____; these bilateral thickenings are called ____
surface ectoderm; caudal hindbrain; otic placodes (2)
ectoderm invaginates in each placode, forming an ____, the edges of which pinch off to form an ____ that separates from surface ectoderm and will become the ____ for each ear
otic pit; otic vesicle; membranous labyrinth
____ extends from otic vesicle to form the _____
diverticulum; endolymphatic duct and sac
2 regions of the otic vesicle
utricular region (dorsal): utricle and semicircular ducts saccular region (ventral): saccule and cochlear ducts
the ____ grows out as an extension from the saccular region and coils to form the _____
cochlear duct; membranous cochlea
vacuoles develop in cartilage surrounding the cochlear duct and unite to form the ____
perilymphatic space
2 divisions of the perilymphatic space, both filled with perilymph
scala vestibuli and scala tympani
cartilage surrounding the cochlear duct ____ to form the ____ encasing the inner ear structures
ossifies; bony labyrinth
cells in walls of coiled duct form the _____
spiral organ of Corti
cell bodies of ____ migrate along coils of cochlear duct and form the ____
CN VIII; spiral ganglion
middle ear cavity is also called ____
tympanic cavity
malleus and incus are associated with pharyngeal arch ___
1
stapes is associated with pharyngeal arch ___
2
_____ is from the first pharyngeal groove or cleft and the ___ is from the first pouch
external acoustic meatus; middle ear
tympanic membrane is made up of ____
ectoderm and endoderm
the auricle or pinna of the external ear develops from ______ : mesenchymal proliferations surrounding the _____ (mesenchyme from 1st and 2nd pharyngeal arches)
6 auricular hillocks; 1st pharyngeal groove
auricles develop at level of ____ but will shift to final position which is at ___ level
1st pharyngeal groove; eye
the lens is derived from the invagination of ____
surface ectoderm
the outer layer of the optic cup becomes the ____ and the inner layer of the optic cup becomes the ____
retinal pigmented epithelium; neural retina
rod and cone photoreceptors are adjacent to the ____, in the outermost layer of the retina
pigmented epithelium
remnant of the ____ in the vitreous body remains in the adult
hyaloid artery (called the hyaloid canal)
the ____ is incorporated into the ____ in the adult
central retinal a. ; optic n.
“key hole” appearance of the iris due to failure of the retinal fissure to close during the 7th week
coloboma
outer layer of the cornea is continuous with _____
surface ectoderm
the middle layer of the cornea is derived from ____
mesoderm
migrating mesenchyme from neural crest cells contribute to the ____ and ____
iris; cornea
the iris forms from ____ which is from _____
mesenchyme; migrated neural crest cells
the cornea is induced by the ____
lens
cornea layers
outer: ectoderm
middle and inner: mesenchyme (migrated neural crest)
