Sonic hedgehog gene
P - base of limbed in ZPA
A - AP patterning
P - apical ectodermal ridge (thickened ectoderm at distal end of each developing limb)
A - organ of dorsal-ventral axis
FGF gene
P - apical ectodermal ridge
A - stim mesoderm for limb lengthening
Homeobox gene
A - segmental organization in craniocadual direction
Fetal landmarks - 1wk
hCG begins after blastocyt implantation
Fetal landmarks - 2wk
Bilaminar disk (epi/hypoblast)
2 cavities - amniotic cavity, yolk sac
2 Eccomp to placenta - cytotrophoblast, syncytiotrophoblast
Fetal landmarks - 3wk
Gastrulation (3layers). Primitive streak, notochord, neural plate begin to form.
Fetal landmarks - 3-8wks
Neural tube formed by neuroectoderm (closes at 4th wk)
SUS to teratogens
Fetal landmarks - 4wk
limb buds
Fetal landmarks - 8wk
fetal movement (looks like baby)
Fetal landmarks - 10wk
genitalia have male/female characteristics
Alar plate
senory - dorsal (same as spinal cord)
Basal plate
Motor - ventral (same as spinal cord)
Surface ectodterm
adenohypophysis (from Rathke's puch), lens eye, epi lining of oral cavity, sensory organ of ear, olfactory epi, epidermis, salivary/sweat, mamm glands
CNS and brain, retina
Neural crest
PNS and non-neural structures nearby

ANS, DRG, cranial nerves, celiac gang, melanocytes, parafollicular (C) cell fo thyroid, schwanna cells, pai/arachoind, bones f the skull, dontoblasts, aorticopulmonary septum
gut tube epi and derivatives (lung, liver, pancreas, thymus, parathyoid, thyroid follicular cells)
msucle, bone, CT, serous linking o body cavities (peritoneum), spleen, CV structures, lymphatis, blood, bladder, urethra, vagina, estachian tube, kidney, adrenal ctx, skin dermis, testes, ovaires
Teratogens - ACE inhibitors
Renal damage
Teratogens - Alcohol
leading cause, MR
FAS - devel retardation, microcephaly, holoprosencphaly, facial abnormalities, limb dislocation, heart and lung fistulas (mech may inhibit cell migration)
Teratogens - alkylating agents
absence of digits (+more)
Teratogens - Aminoglycosides
CN8 tox
Teratogens - Cocaine
abn development, addiction, placental abruption
Teratogens - DES - diethylstilbestrol
vaginal clear cell adenoca.
Teratogens - folate antag
neural tube defect
Teratogens - Iodide (lack or xs)
congential goiter or hypoT
Teratogens - lithium
Ebsteins' anomaly (atrailized RV)
Teratogens - maternal diabetes
Caudal regression syndome (anal atresia to sirenomelia -mermaid)
Teratogens - smoking (nicotine, CO)
Preterm labor, placental problems, IUGR, ADHD
Teratogens - tetracyclines
discolored teeth
Teratogens - Thalidomide
limb defects - flipper limbs
Teratogens - Valproate
Inhibition of folate abs
Teratogens - Vit A (xs)
sp. abortions, birth defects (cleft palate, cardiac abn)
Teratogens - Warfarin
bone deformities, fetal hemorrhage, abortion
Teratogens - Xray, anticonvulsants
mutliple anomalies
Patent urachus
urachus - duct between the bladder and yolk sac, devel from allantois in 3rd week
patent - urine discharge from umbilicus
Vesicourachal diverticulum
outpoutching of bladder
Vitelline fistula
Vitelline duct - connects yolk sac to midgut lumen - normally obliterated at 7th week
Fistula - failure to close, meconium discharge from umbillicus
Meckels diverticulum
Partial closure of vitellin duct (patent part attached to ileum)
may have ectopic gastric mucosa (melena and pericumbilical pain)
Truncus arteriosus (TA)
GRT - ascending aorta and pulm trunk
Bulbus cordis
RV and smooth parts (outflow track) of LV/RV
Primitive ventricle
trabeculated LV/RV
Primitive atria
Trabeculated LA/RA
Left horn of sinus venosus (SV)
Coronary sinus
Right horn of SV
smooth part RA
Right common cardinal vein and right anterior cardinal ven
Fetal erythropoiesis
yolk sac (3-8), liver (6-30), speen (9-28), BM (28+)

young liver syn blood
Telencephalon-->cerebral hemispheres, lateral ventricles

Diencephalon --> thalami, etc. 3rd ventricle
Midbrain (maybe part aqueduct?)
Metencephalon - Pons, cerebellum, part of aqueduct, part 4th ventricle

Myelencephalon - medulla, part 4th ventricle
Neural tube defects
increase AFP in amniotic fluid, maternal serum, and CSF. AChE is alos incr in CSF.
normally fuses at 4th week (assoc with low folic acid intake)

Spina bifida oculta - bony failure, dura intact (tuft of hair)
Meningocele - meninges herniate (outpocket of subaracnoid space)
Myelominingocele - meninges and spinal cord herniate
malf of anterior end of the neural tube, NO brain/calvarium
incr. AFP, polyhydramnios

forebrain anomalies
decr. separation of cerebral hemispheres, results in cyclopia, assoc with Pataus', FAS, cleft lip/palate

forebrain anomalies
Chiari I
cerebellar tonsillar herniation through foramen magnum w/ aqueductal stenosis and hydrocephaly. (often presents with syringomyelia and lumbar myelomingocele)

posterior fossa malformation
large posterior fossa, absent cerebellar vermis with cystic enlargement of 4th V. Canlead to hydrocephalus adn spina bifida
enlargement of central canal of spinal cord (think syringe!)
spinothal tract finbers are damaged first--> "cape like" bilaterla loss pain and temp in upper extremities w/ preservation fo touch
Aortic arch - 1st
Maxillary artery (br of external carotid) (1=MAX)
Aortic arch - 2nd
Stapedial artery and hyoid artery (Second = Stapedial)
Aortic arch - 3rd
common carotid, adn prox part internal carotid (C=3rd letter)
Aortic arch - 4th
L - aortic arch
R- r. subclavian
Aortic arch - 6th
prox part pulm aa and (on L only) ductus arteriosus
Thryoglossal duct cyst
Midline neck syste, that iwll move with swallowing. May have patent duct that goes to foramen cecum
Cleft lip
fail of fusion of maxillary and medial nasal processes (primary palate)
Cleft palate
failure of fusion of lateral paltine processes, nasal septum, and/or median palatine processes (secondary palate)
Tracheoesophageal fistual
cyanosis, choking/vomiting w/ feeding, air bubble in stomach on CXR, polyhyradmnios
Congenital pyloric stenosis
Hypertrophy of the pylorus-->obstruction
projectile vomit at 2wk, palpable mass epigastric ("olive")
Annular pancreas
ventral pancreatic bud abnormally wraps around 2nd part duodenum (duodenal narrowing)
Pancreas divisum
ventral/dorsal parts fail to fuse at 8wks
Potter's syndrome
Bilateral renal agenesis-->oligohydramnios-->limb deformities, facial deformities, pulmonary hypoplasia

Malformation of ureteric bud
"babies that can't pee in utero develop potters"
Bicornuate uterus
imcomplete fusion of paramesonephric ducts-->UT abn and infertility
abd opening of urethra on inferior (ventral) side of penis. Due t failure of urtheral folds to close
abd opening of penil urethra on the superior (dorsal) sid eof penus due to faulty positioning of the genital tubercle
Brachial arch - 1
C - mandible, maleus incus, spenomandibular ligament
M - Mastication (masseter, temporalis, m/l pterygoid), mylohyoid, ant belly digastric, ant 2/3 tongue, tensor veli palatini, tensor tympani,
N - CN V2/3
Treacher Colllins syndrome
1st brachial arch neural crest fails to migrate-->manidulbe hypoplasia, facial abn
Brachial arch - 2
C - stapes, styloid process, inf. horn hyoid, stylohyoid ligament
M - facial expression, stapedius, stylohyoid, post belly digastric
Brachial arch - 3
C - greater horn hyoid
M - Stylopharyngeus
N - CN IX (glossopharyngeal)

congenital pharyngocutaneous fistula - persistence of cleft and puch -->fistula between tonsillar area, cleft in lateral neck
Brachial arch - 4-6
C - thyroid, cricoid, arytenoids, corniculate, cuneiform
M - 4th : pharyngeal constrictors, cricothyroiid, levator veli palatini,
M - 6th: all intrinsic muscle of larynx except cricothyroid
N - 4th - CN X (superier laryngeal branch - swallowing)
N - 6th - CN X (recurrent laryngeal branch - speaking)