Embryology and anatomy Flashcards
Sonic hedgehog gene mutations
Holoprosencephaly (A-P axis)
Wnt-7 gene mutation
Limb development (dorsal-ventral axis)
FGF gene mutation
Lengthening of limbs
Homeobox (Hox) genes
Appendages in the wrong locations
Implantation of the blastocyst occurs?
Stick at 6 (days)
Formation of the bilaminar disc timing?
2 weeks (=2 layers)
Formation of the trilaminar disc timing?
3 weeks (=3 layers) Primitive streak, notochord, mesoderm and its organization, and neural plate begin to form
Neural tube formed by what cell layer?
Neuroectoderm (neural tube closes at 4 weeks)
When is the fetus most susceptible to teratogens?
3-8 weeks
What occurs at week 4 or embryogenesis?
Limb development (4 limbs)
What occurs at week 6 of embryogenesis?
Fetal cardiac activity visible by transvaginal US
What occurs at week 10 of embryogenesis?
Genitalia have female/male characteristics
What is the process called that forms the trilaminar disc?
Gastrulation (Ectoderm, mesoderm, and endoderm germ layers form)
What comes from surface ectoderm?
Epidermis, adenohypophysis (Rathke pouch), lens of the eye, epithelial linings of oral cavity, sensory organs of ear, and olfactory epithelium, anal canal below the pectinate line, parotid, sweat, and mammary glands
What comes from neuroectoderm?
Brain (Neurohypophysis, CNS neurons, oligodendrocytes, astrocytes, ependymal cells, pineal gland), retina and optic nerve, spinal cord
*Think CNS
What comes from neural crest?
CA MOTEL PASS *Think PNS and nearby) Craniofacial bones Arachnoid/pia mater Melanocytes Odontoblasts (teeth) Trachael cartilage Enterochomaffin-like cells Layrngeal cartilage Parafollicular cells (thyroid) All ganglia (including adrenal medulla) Schwann cells Spiral septum (heart development)
Mesoderm
M=middle=meat layer
Muscle, bone, CT, serious linings of body cavities, spleen, CV structures, lymphatics, blood, wall of gut tube, vagina, kidneys, adrenal cortex, dermis, testes, ovaries
Mesoderm defects?
VACTREL Vertebral defects Anal atresia Cardiac defects Tracheo-esophageal fistula Renal defects Limb defects (bone and muscle)
Endoderm
Gut tube epithelium
Urethra
Luminal epithelial derivatives (lungs, liver, gallbladder, pancreas, eustachian tube, thymus, parathyroid, thyroid follicular cells)
DEformation
Extrinsic disruption, occurs after embryonic period
Malformation
Intrinsic disruption, occurs during embryonic period
Aplasia
Absent organ development despite present primordial tissue
Disruption
Secondary break down of previously normal tissue (amniotic band syndrome)
Teratogen: ACE inhibitors
Renal damage
Teratogen: alkylating agents
Absence of digits
Teratogen: aminoglycosides
CN VIII (“a min gly hit the baby in the ear”)
Teratogen: Carbamazepine
Facial dysmorphism, dev. delay, neural tube defects phalanx/fingernail hypoplasia
Teratogen: Diesthylstilbestrol (DES)
Vaginal clear cell adenocarcinoma, congenital Mullerian anomalies
(Old oral contraceptive)
Teratogen: folate antagonist
Neural tube defects
Teratogen: Isotretinoin
Severe/multiple birth defects
Teratogen: lithium
Ebstein anamoly (atrialized right ventricle–>tricuspid vavle in the ventricle)
Teratogen: methimazole
Aplasia cutis congenita
Teratogen: Phenytoin
Fetal hydantoin syndrome: cleft palate, cardiac defects, phalanx/finger hypoplasia
Teratogen: Tetracyclines
Discolored teeth
Teratogen: Thalidomide
Limb defects
Teratogen: valproate
Inhibition of maternal folate absorption–>neural tube defects
folATE~valproATE
Teratogen: Warfarin
Bone deformities, fetal hemorrhage, abortion, opthalmologic abnormalities
Teratogen: Alcohol
FAS- birth defects and ID
Teratogen: cocaine
Abnormal fetal growth and fetal addiction, placental abruption
Teratogen: Smoking
Low birth weight, preterm labor, placental problems, IUGR, ADHD
nicotine=vasoconstriction
CO–>impaired O2 delivery
Teratogen: Iodine (lack or excess)
Congential goiter or hypothyroidism (cretinism-severely stunted physical and mental growth)
Teratogen: Maternal diabetes
Caudal regression syndrome (anal atresia to sirenomelia), congenital heart defects, neural tube defects
Teratogen: Vit A excess
Extremely high risk for spontaneous abortions and birth defects (cleft palate/cardiac)
Teratogen: X rays
Microcephaly, ID (minimize with lead shielding)
Most common type of monozygotic twins? When does separation occur?
Monochorionic, diamniotic (75% of monozygotic twins)
4-8 days after formation of morula
Separation of monozygotic twins at 0-4 days?
Dichorianic, diamniotic between 2 cell stages and morula
Cytotrophoblast is part of what?
Fetal component of placenta
What is the cytotrophoblast made out of?
Inner layer of chorionic villi
Syncytiotrophoblast is part of what?
Fetal component of placenta
Syncytiotrophoblast is made out of?
Outer layer of chorionic villi, secrets hCG (structually similar to LH, stimulates corpus luteum to secrete progesterone during first trimester)
Decidua basalis if part of what?
Maternal component of the placenta
Decidua basalis is made out of what?
Derived from endometrium. Maternal blood in the lacunae.
How many umbilical arteries are there?
2
How many umbilical veins are there?
1
What vessel deliveries deoxygenated blood from the fetal internal iliac arteries to the placenta?
Umbilical arteries
What vessel delivers oxygenated blood from the placenta to the IVC via the ductus venosus
Umbilical vein
Where are the umbilical arteries and vein derived from?
Allantois
What does the allantois become?
Urachus, a duct between fetal bladder and yolk sac
Patent urachus
Total failure of urachus to obliterate–>urine discharge from umbilicus
What forms from the yolk sac in week 3 of embryogenesis?
Allantois, which extends into urogenital sinus
Urachal cyst
Partial failure of urachus to obliterate; fluid-filled cavity lined with uroepithelium, between umbilicus and bladder
Presence of urachal cyst leads to risk of?
Infection and adenocarcinoma
Vesicourachal diverticulum
Slight failure of urachus to obliterate–>outpouching of the bladder
Vitelline duct
Connection between the yolk sac and the midgut lumen