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Clinical
Applications in Embryology |
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Clinical Topic |
Description |
Notes |
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Bone
Age |
Determined
by fusion of epiphyseal centers (in X-ray) |
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Rickets |
Deficiency
of Vitamin D in children; impairs calcium absorption and calcification of
epiphyseal plate- deformed, shortened and bowed limbs |
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Spina
bifida: |
Failure
of vertebral arches to fuse |
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Occulta |
Although vert
arches have not fused, there are no symptoms except for small tuft of hair
that may appear over the site of faulty fused vertebrae |
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Cystica with meningocoele |
CSF
begins to produce a bulge (cyst) which can be seen readily |
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Cystica with Meningomyolocele |
While it
also involves CSF producing a bulge (cyst), the spinal cord, dorsal/ventral
roots and DRG bulge out as well and are present within the cyst |
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Cystica with Myeloschisis
(Raschoshisis) |
The
spinal cord is opened up and exposed covered by a thin membrane |
Nerve
involvement may occur; most severe |
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Klippel-feil
Syndrome (brevicollis) |
Cervical
vertebrae are less than normal, restricted movements |
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Hemivertebra
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Absence of
one of two chondrific centers in each mesenchymal centrum |
Scoliosis
results |
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Achondroplasia |
Early
premature fusion of epiphyseal plates |
Autosomal
dominant disorder; along with gigantism, acromegaly and cretinism, achondroplasia
may be related to advanced paternal age |
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Craniosynostosis/
Scaphocephaly |
Early
closure of sagittal suture causing wedge shaped skull |
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Oxycephaly/
turricephaly |
Early
closure of coronal suture causing tower skull |
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Plagiocephaly |
Premature
fusion of coronal or lamboidal suture on one side causing a twisting in the
skull |
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Bifid
Sternum/ Sternal Foramen |
Non-union
or imperfect fusion of the sternal mesechymal plates |
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Acrania
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Calvarium
is absent… think meroencephaly |
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Absence
of muscle |
Or
presence of accessory muscle is variation. May be due to early splitting of
muscle masses |
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Amelia |
Absence
of limb |
May arise
from usage of thalidomide in early stages of pregnancy (4-7 weeks) |
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Meromelia |
Partial
absence of limb |
May arise
from usage of thalidomide in latter stages of pregnancy |
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Syndactyly |
Fusion of
digits; mesenchyme between digits fails to develop |
May arise
due to Genetics: autosomal dominant, recessive or X-linked traits; Environmental:
Thalidomide, oligohydramnios, and amniotic band syndrome; Multifunctional
Inheritance:Combo of above mentioned problems |
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Polydactyly |
Refers to
extra digits; apical ectodermal ridge breaks into more than normal digital
rays |
May arise
due to Genetics: autosomal dominant, recessive or X-linked traits; Environmental:
Thalidomide, oligohydramnios, and amniotic band syndrome; Multifunctional
Inheritance:Combo of above mentioned problems |
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Branchial
Cysts |
Failure
of cervical sinus to close |
May be
seen along to surface of skin over the sternocleidomastoid |
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Branchial
Sinus |
Opens up
on the anterior border of lower SCM surface or into the intratonsillar cleft;
external sinus is due to failure of the obliteration of 2nd pharyngeal groove
and internal sinus is from persistent cervical sinus and failure of the 2nd
pharyngeal pouch to obliterate |
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Branchial
fistula |
opening between
intratonsillar cleft and SCM surface of neck to improper obliteration of
cervical sinus |
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First
Arch Syndrome |
Inadequate
migration of neural crest cells, 1st arch fails to develop properly |
Two types
are Treacher-Collins and Pierre Robin syndromes… |
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a) Treacher-Collins Syndrome |
Lower
eyelids, zygomatic bones and external ear show defects |
Also
called Mandibulofacial Dysostosis |
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b) Pierre Robin Syndrome |
Underdeveloped
mandible, cleft palate and defects in eye |
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Digeorge
Syndrome |
Failureo
3rd and 4th pouches to develop into thymus and parathyroids. Increased susceptibility to infection,
anomalies of mouth (fish mouth), low set ears, thyroid hypoplasis and cardiac
anomalies |
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Thyroglossal
Cyst & Sinus |
Failure
of thryoglossal to obliterate; median cyst may arise and infection may cause
rupture to become a cyst |
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Ectopic
Thyroid |
Thyroid
develops on foramen cecum of tongue (lingual thyroid), above the hyoid
bone (sublingual thyroid), in the neck (cervical thyroid), or
even on the thyrohyoid muscle |
Sometimes
may be the only thyroid to develop… Warning: during surgical procedure
to remove ectopic thyroid masses, make sure to check another is there! ! |
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Ankyloglossia |
Short frenulum-
tongue cannot be protruded |
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Macroglossia |
Large
tongue due to lynphangioma or hypertrophy of muscles |
May be
related to Hanhart Syndrome (?) |
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Bifid
Tongue |
Failure
of lingual swellings to fuse |
Dude… your
tongue looks serpentine n' shit… |
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Microglossia |
small
tongue |
May be
related to Hanhart Syndrome (?) |
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Cleft
lip |
Median
cleft lower lip
result due failure of mandibular prominences to fuse; cleft upper lip can
be unilateral or bilateral; unilateral failure/fusion between
maxillary process and nasal prominences; median cleft upper lip (harelip) non-fusion
of medial nasal prominences |
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Cleft
palate |
Failure
development of intermaxillary segment, failure/fusion between primary & secondary
palate; posterior cleft palate failure/fusion between lateral palatal
processes |
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Obliqe
facial cleft |
Extends
from medial angle of eye and upper lip- failure/fusion between maxillary
prominences and lateral/medial nasal prominences; nasolacrimal duct is open
at bottom of cleft |
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Transverse
facial cleft |
Uni/bilateral
cleft extending from angle of mouth to ear; failure/union between mandibular
and maxillary processes; gives rise to uni/bilateral macrostomia |
Microstomia-
small mouth |
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Bifid
nose |
Failure/fusion
of medial nasal prominences |
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Enamel
hypoplasia |
Failure
of enamel formation- nutritional deficiency |
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Congenital
discoloration of teeth |
Tetracycline-
yellow teeth; black teeth may arise due to erythroblastosis fetalis |
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Natal
teeth |
Erupted
teeth at time of birth |
Discomfort
during breast feeding; lacerated tongue; aspirated air passage by teeth |
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Pharyngeal
hypophysis |
Due to
persistence of Rathkey's pouch in roof of stomodeum (mouth) |
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Remnant
of stal of Rathkey's pouch in body of sphenoid |
Can be
seen in radiographs of skull |
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Craniopharyngiomas |
Remnant
of Rathkey's pouch in roof of pharynx or basisphenoid |
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Meroanencephaly |
Associated
with polyhydramnios & increase in alpha fetoprotein in amniotic sac;
failure of closure of anterior neuropore- associated with abnormal dev'l of
forebrain and defective formation of cranial vault |
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Hydrocephalus |
Obstructive
Type- Obstruct
aqueduct of sylvius, IV foramen or foramina of 4th ventricle. Absorption of CFSis interfered resulting in
dilation of ventricles and head; Non-obstructive- defect at site of
absorption |
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Herniation
of medulla and cerebellum into vertebral canal through foramen magnum |
Associated
with non-obstructive type of hydrocephalus |
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Hydranencephaly |
Cerebral
hemispheres absent, seen as thin membranes with enlarged head. Interference with blood supply to brain
during dev'l |
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Microencephaly |
Small
skull, small brain caused by genetic/environmental |
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Cranium
bifidum |
Defect in
cranial vault in midline |
Associated
with: meningocele, meningoencephalocele, or meningohydroencephalocele |
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Double
Aortic Arch |
Failure
of right dorsal aorta (caudal to rt. 7th intersegmental artery) to disappear;
may cause constricting of the esophagus and trachea- results in wheezing respiration
aggravated by feeding, crying flexion of neck |
See
Persaud, Figure 14-42, pg. 389 |
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Right
Sided Arch of Aorta |
Persistence
of distal segment of right dorsal aorta and involution of segment of left dorsal
aorta below left 7th intersegmental artery; may be retroesophageal and along
with ligamentum arteriosum constrict trachea and esophagus |
See
Persaud, Figure 14-43, pg. 390 |
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Co-arctation
of Aorta |
Constriction
of areas of the aortic arch due to either incorporation of muscle tissue from
the ductus arteriosus into the aortic arch (cranial or caudal to the ductus
arteriosus) OR improper involution of the left dorsal aorta caudal to the 7th
intersegmental arch |
Post
ductal (caudal to ductus arteriosus) is more common than preductal (cranial
to ductus arteriosus); MORE common in males than in females; may be
associated with Turner's Syndrome (XO anomaly); also often associated w/
bicuspid aortic valve; See Persaud, Figure 14-41, pg. 388 |
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Retroesophageal
Right Subclavian Artery |
Due to
the abnormal involution of the right fourth aortic arch and dorsal aorta
caudal to the 4th arch; instead, left dorsal aorta caudal to 7th
intersegmental artery (and 7th intersegmental artery) remains and becomes the
right subclavian that can be seen swinging back behind esophagus; may cause
constriction ring around esophagus and trachea. |
See
Persaud's, Figure 14-44, pg. 391 |
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Patent
Ductus Arteriosis |
Most common
congenital problem of vascular system; more common in females; associated
with maternal rubella infection in early pregnancy; Premature infants PDA
since less aerated lungs produce insufficient bradykinin |
May be
associated w/ coarctation of aorta, Turner's syn, pulmonary stenosis, or
transposition of great vessels. In premature infants or infants w/
respiratory distress syndrome, ductus arteriosus fails to involute because of
hypoxia |
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Detachment
of Retina |
Injury to
eye causes separation of neural and pigment layers of retina |
Note that
originally retinal layers developed with these two layers separate… |
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Coloboma
(…no, Jav, not |
Deficiency
in choroid and/or iris (keyhole pupil); failure/closure of choroid fissure; may
extend to ciliary body and retina palpebral colomba, notching of upper eyelid
'cause screwy eyelid development |
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Congenital
cataract |
Opaque
lens due to maternal rubella infxn. |
associated
with persistance of hyaline artery and hyaline canal |
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Persistent
pupillary membrane |
Remnants
of pupillary membrane may persist over lens affecting normal vision |
Total
persistence of pupillary membrane may cause congenital atresiaof pupil |
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Aphakia |
Absence of
lens due to failure of optic vesicel to induce lens formation |
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Aniridia |
Absence
of iris |
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Cryptophthalmos |
Hidden
eye resulting due to failure palpebral fissure formation; small eye defective
under skin |
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Anophthalmos |
Failure of
eyeball formation |
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Microphthalmos |
eye small
w/ or w/o other abnormalities |
associated
w/ rubella virus, taxoplasma gondii, and herpes simplex virus |
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Persistent
hyaloid artery |
May be
present in vitreous body or extend throughout and attach to lens |
Related
to possible microphthalmos or otherwise normal, functioning eye |
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Cyclopia |
Eyes
partially or fully fused & single orbit; tubular nose (proboscis) lies
above eye; rare & due severe suppression of midline cerebral structures
(holoprosencelaphy) developing from cranial part of neural plate |
WITHOUT
A DOUBT the single most disturbing picture of the course! |
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Congenital
deafness (deaf mutism) |
Spiral organ
of Corti not formed properly; due to rubella infxn or genetic factors |
May form
as part of first arch syndrome |
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Auricular
appendages |
Formation
of accessory auricular hillocks |
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Preauricular
sinuses |
Seen in
anterior area of auricle; unknown causes; maybe caused by abnormal
development of auricular hillocks or defective closure of dorsal end of 1st
pharyngeal groove |
Associated
with internal anomalies like deafness and kidney malformations |
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Low
set auricles |
Seen in
chromosomal abnormalities like Trisomy 18 |
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Anotia |
Absence
of auricle; rare |
Related
to First Arch Syndrome |
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Microtia |
Small
auricles, suppression of auricular hillocks |
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Atresia
of external auditory meatus |
Failure of
meatal plug to canalize |
Related
to First Arch Syndrome |
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Congenital
fixation of stapes |
Results
in conductive deafness |
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Congenital
cholesteatoma |
Epithileal
rest cells appear as crystal-like structures on inner surface of tympanic
membrane |
Cyst
formed from cells of meatal plug displaced while plug canalized to form
external ear canal |