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84 Cards in this Set
- Front
- Back
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Sonic Hedgehog Gene
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Produced in zone of polarizing acitivty and is responsible for anterior-posterior axis
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Wnt-7 gene
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Produced at apeical ectodermal ridge and necessary for dorsal-ventral axis organization
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FGF Gene
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Produced at apical ectodermal ridge and stimulates mitosis of underlying mesoderm - limb lengthening
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Homeobox Gene
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Segmental organization of embryo in craino-caudal direction
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Fetal landmarks Day 0
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Fertilation by sperm - zygote formation
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Fetal Landmarks within week 1
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hCG secretion after blastocyst implantation
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Fetal Landmarks within week 2
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Bilaaminar disk comprised of epiblast and hypoblast
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Fetal Landmarks within week 3
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Gastrulation. Formation of primitive streak, notochord, and neural plate
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Fetal Landmarks weeks 3-8
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Neural tube formed by neuroectoderm. Closure of neural tube by week 4.
Organogenesis Period of susceptibility to teratogens |
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Fetal Landmarks week 4
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Heart beat
Upper and lower limb buds |
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Fetal Landmarks within week 8
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movement
fetus looks like baby (fetal period) |
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Fetal Landmarks week 10
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genitalia have male or female characteristics
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Fetal Spinal Cord and Neural Development
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Fetal spinal cord
Alar - dorsal - Sensory Basal - ventral - Motor Neural Development Notochord induces ectoderm to form neuroectoderm and neural plate neural plate gives rise to neural tube and neural crest Notochord becomes nucleus pulposus (part of intervertebral disk in adults) |
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Rule of 2's
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2nd week
2 germ layers (epiblast, hypoblast): bilaminar disk 2 cavities (amniotic cavity, yolk sac) 2 placental parts (cytotrophoblast, syncytiotrophoblast) epiblast - ectoderm precursor, invaginates to form primitive streak, which gives rise to intraembryonic mesoderm and part of endoderm |
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Rule of 3's
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3rd week
3 germ layers (ecto, meso, endo): gastrula |
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Rule of 4s
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4th week
4 heart chambers 4 limb buds grow |
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Ectoderm Derivatives
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Surface ectoderm - adenohypophysis (rathke's pouch), sensory organs of ear, lens, oral and olfactory epithelium, epidermis, salivary/sweat/mammary glands
Neuroectoderm - Brain (CNS and neurohypophysis), retina, spinal cord Nerual crest - ANS, PNS ( dorsal root ganglia, CNs, celiac ganglion), melanocytes, chromaffin cells of adrenal medulla, parafollicular C cells of thyroid, bones of skull, odontoblasts (Odonto-Crest toothpaste), aorticopulmonary septum |
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Endoderm Derivatives
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Gut tube epithelium (lungs, liver, pancreas, thymus, parathyroid, thyroid follicular cells
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Mesoderm Derivatives
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Muscle, bone, CT, serosas, spleen, CV, lymph, blood, bladder, urethra, vagina, eustachian tube, kidneys, adrenal cortex, dermis, testis, ovaries
Defects mnemonic: VACTERL - Vertebral, Anal atresia, Cardiac, Tracheo-Esophageal fistula, Renal, Limb |
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Organ morphogenesis errors
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Malformation - intrinsic disruption (week 3-8)
Deformation - extrinsic disruption (after week 8) Agenesis - absent organ due to absent primordial tissue Hypoplasia - incomplete organ development in presence of primordial tissue Aplasia - absent organ in presence of primordial tissue |
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Twinning
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Day 3 - chorion formed
Day 8 - amnion formed Before day 3 - Dichorionic - 2 of everything: aminion, chorion dizygotic or monozygotic Before day 8 - Monochorionic, diamniotic - monozygotic - shared chorion with thin membranes seperating amnions After day 8 - Monochorionic, monoamniontic - risk for conjoined |
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Placenta (Fetal and Maternal
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Fetal
Cytotrophoblast - inner layer of chorionic villi - makes cells Syncytiotrophoblast - outer layer of chorionic villi - secretes hCG Maternal Decidual basalis - maternal blood in lacunae, derived from endometrium |
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Umbilical Cord
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2 arteries - deoxy blood fetal internal iliac > placenta
1 vein - oxy blood placenta > fetus IVC Urachus Wharton's Jelly covered in amniotic epithelium derived from allantois |
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Heart derivatives
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Truncus arteriosus - Ascending Aorta and Pulmonary Trunk, aorticopulmonary septum
Bulbus Cordis - RV and smooth/outflow tracts of LV and RV Primitive Ventricle - Portion of LV Primitive atria - trabeculated LA and RA Left Horn of sinus venosus - Coronary sinus Right Horn of sinus venosus - smooth part of RA Right common cardinal vein and right anterior cardinal vein - SVC |
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Interventricular septum development
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1. Muscular ventricular septum formation with interventricular foramen
2. AP septum fuses with muscular septum to form membranous interventricular septum, closure of interventricular foramen 3. Endocardial cushion growth - separation of atria from ventricles, atrial separation and membranous interventricular septum |
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Interatrial septum development
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1. Septum primum grows toward endocardial cushions (foramen primum shrinks)
2. Perforations in septum primum form foramen secundum, maintaining R>L shunt (foramen primum gone) 3. Septum secundum growth with permanent foramen ovale 4. Upper septum primum degeneration with septum segundum enlargment 5. Septum primum remaining forms valve of forament ovale 6. Secundum and primum fuse > atrial septum 7. closure of foramen ovale after birth with increased LA pressure - PFO caused by excessive resorption of primum or secundum |
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Fetal Erythropoiesis
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Young Liver Synthesizes Blood
Yolk Sac - 3-8 wks Liver - 6-30 wks Spleen - 9-28 wks Bone Marrow - 28+ wks FHb - alpha2, gamma2 AHb - alpha2, beta2 |
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Fetal circulation
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umbilical vein - 80% saturated
placenta > umbilical vein > ductus venosus (bypass liver) > IVC > RA > FO > LA > LV > Ao > Internal iliac > umbilical arteries > placenta pulmonary veins > SVC > RA > RV > Pulmonary Artery > Ductus Arteriosus > Ao Prostaglandins - PDA patency Indomethicin - PDA closure |
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Branchial Cleft derivatives
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1st cleft - external auditory meatus
2nd-4th clefts - temporary cervical sinsuses which become obliterated by 2nd arch mesenchyme persistent cervical sinus - branchial cleft cyst within lateral neck |
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1st Branchial Arch
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Cartiage - Meckel's: Mandible, Malleus, incus, spheno-Mandibular ligament
Muscles - Mastication (temporalis, masseter, pyterygoids), Mylohyoid, anterior belly of digastric, tensor tympani, tensor veli palatini, anterior 2/3 tongue Nerves - CN V2 and V3 (chewing) Abnormal - Treacher Collins Syndrome - failed 1st arch migration > mandibular hypoplasia, facial abnormalities |
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2nd Branchial Arch
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Cartilage - Reichert's: Stapes, Styloid process, lesser horn of hyoid, Stylohyoid ligament
Muscles - Facial Expression: Stapedius, Stylohyoid, posterior belly of digastric Nerves - CN VII (facial expression) |
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3rd Branchial Arch
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Cartilage: Greater horn of hyoid
Muscles: Stylopharyngeus Nerves: CN IX Abnormal - persistance of cleft and pouch - Congenital pharyngocutaneous fistula (between tonsillar area and cleft in lateral neck) |
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4th - 6th Branchial Arch Derivatives
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Cartilages: Thyroid, cricoid, arytenoids, corniculate, cuneiform
Muscles: 4th - pharyngeal constrictors: cricothyroid, levatorveli palatini Muscles: 6th - intrinsic laryngeal muscles except cricothyroid Nerves: 4th - CN X - superior laryngeal branch (swallowing) Nerves: 6th - CN X - recurrent laryngeal branch (speaking) 3rd and 4th arch > posterior 1/3 of tongue 5th makes no major contribution |
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Branchial Pouch derivatives
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1st - middle ear cavity, eustachian tube, mastoid air cells (endoderm lined structures of ear)
2nd - epithelial lining of palatine tonsil 3rd - dorsal wings - left and right inferior parathyroids 3rd - ventral wings - thymus 4th - dorsal wings - superior parathryoids 3rd pouch ends up below 4th DiGeorge - abberant 3rd and 4th pouch development - thymic aplasia/hypocalcemia (PTH) |
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Brain development
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Prosencephalon (Telencephalon > Cerebral Hemisphere > Lateral Ventricle)
Prosencephalon (Diencephalon > Thalami > 3rd Ventricle) Mesencephalon (Mesencephalon > Midbrain > Cerebral Aqueduct) Rhombencephalon (Metencephalon > Pons and Cerebellum > 4th Ventricle) Rhombencephalon (Myelencephalon > Medulla) |
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Aortic Arch Derivatives
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1st - Maxillary artery
2nd - Stapedial artery and hyoid artery 3rd - Common Carotids and proximal ICA 4th - Left -aortic arch 4th - Right - proximal subclavian 6th - proximal pulmonary arteries and ductus arteriosus (on left) |
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Branchial Apparatus
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CAP covers outside from inside
Clefts=ectoderm Arches=mesoderm (muscle, arteries) and neural crests (bone, cartilage) Pouches=endoderm |
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Tongue
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Taste - CN VII, IX, X (solitary nucleus)
Pain - CN V3, IX, X Motor - CN XII 1st arch anterior 2/3 3rd and 4th arch posterior 1/3 Muscles from occipital myotomes |
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Thyroid Development
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descends from pharanyx (remnant is foramen cecum of tongue), connected by thyroglossal duct (may persist as pyramidal lobe of thyroid.
anomalies - ectopic thyroid tissue in tongue and thyroglossal duct cyst (midline neck, moves with swallowing) |
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GI Development
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Foregut (Celiac artery) - pharynx to duodenum (Spleen from dorsal mesentery but supplied by celiac artery)
Midgut (SMA) - duodenum to transverse colon. Week 6 - herniation through umbilical ring. Week 10 - return to abdominal cavity and rotation around SMA Hindgut (IMA) - transverse colon to rectum |
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Pancreas
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Foregut > dorsal and ventral buds
Ventral > head, uncinate process, main pancreatic duct Dorsal > body, tail, isthmus, accessory pancreatic duct |
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Male Genital Development
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SRY on Y chromosome > testis determining factor > testes development
Mullerian inhibitory factor from Sertoli Cells > suppression of paramesonephric duct (paramesonephric duct is default) Androgens from Leydig Cells > development of mesonephric duct (needs induction) Mesonephric Duct - SEED - Seminal vesicles, Epididymis, Ejaculatory duct, Ductus Deferens DHT Genital tubercle > Glans penis and corpus carvernosum/spongiosum UG sinus > Bulbourethral glans and prostate UG folds > Ventral shaft of penis Labioscrotal swellin > Scrotum |
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Female Genital Development
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Default - mesonephric duct degenerates and paramesonephric duct develops
Paramesonephric duct - Fallopian tube, Uterus, upper 1/3 of vagina Estrogen Genital Tubercle > Glans Clitoris and Vestibular bulbs UG Sinus > Greater vestibular glands (Bartholin) and Urethral and Paraurethral glands (Skene) UG Foids > Labia minora Labioscrotal folds > Labia majora |
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Gubernaculum
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band of fibrous tissue
female - ovarian ligament and round ligament of uterus male - anchors testes within scrotum |
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Processus vaginalis
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Evagination of peritoneum
female - obliterated male - tunica vaginalis |
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Kidney Development
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Pronephros - degrades after week 4
Mesonephros - 1st trimester kidney > later male genital Metanephros - appears in week 5, growth through week 32-36 - permanent ureteric bud - caudal end of mesonephros > ureter, pelvis, clayces and collecting ducts by week 10 metanephric mesenchyme - induced by ureteric bud > glomerulus, renal tubules to distal convoluted tubule uteropelvic juntion - last to canalize, common site for obstruction and hydronephrosis in fetus |
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ACE inhibitors
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Renal damage
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Fetal alcohol syndrome
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pre and postnatal developmental retardation, microcephaly, holoprosencephaly, facial abnormalities, limb discoloration, heart and lung fistulas
Mechanism may include cell migration inhibition |
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Alkylating Agents
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Absence of Digits
multiple anomalies |
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Aminoglycosides
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CN VIII toxicity
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Cocaine
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abnormal development and fetal addiction
placental abruption |
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Diethylstilbestrol (DES)
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Vaginal Clear Cell Carcinoma
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Folate deficiency/antagonists
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NTDs
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Iodide (lack or exess)
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Goiter/hypothyroidism
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Lithium
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Ebsteins anomaly (atrialized right ventricle)
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Maternal diabetes
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Caudal regression syndrome - anal atresia to sirenomelia (mermaid syndrome - leg fusion)
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Smoking (nicotine/CO)
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preterm, placental problems, intrauterine growth restriction (IUGR), ADHD
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Tetracyclines
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Discolored teeth
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Thalidomide
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Limb defects - flipper
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Valproate
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Folate absorption inhibtion - NTDs
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Vitamin A (excess)
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spontaneous abortions
cleft palate and cardiac abnormalities |
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Warfarin
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Bone deformation
hemorrhage abortion |
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x-rays, anticonvulsants
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multiple anomalies
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Urachal duct abnormalities
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3rd week - yolk sac > allantois > urachus (duct between bladder and yolk sac)
Failure of obliteration of urachus: Patent urachus: urine discharge from umbilicus Vesicourachal diverticulum - bladder outpouching |
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Vitelline Duct abnormalities
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7th week - obliteration of vitelline duct (connects yolk sac to midgut lumen)
Bitelline fistula - duct closure failure > meconium/poop discharge from umbilicus Meckel's diverticulum - partial closure, patency to ileum > ectopic gastric mucosa > melena and periumbilical pain |
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Spina Bifida Occulta
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Bony spinal canal does not fully close, no herniation, intact dura
Lower vertebral levels Tuft of hair |
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Meningocele
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meninges herniate through spinal canal defect
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Myelomeningocele
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meninges and spinal cord herniate through spinal canal defect
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NTD
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neuropore fusion failure in 4th week leading to persistant connection of amniotic cavity and spinal canal (vertebral arch)
low folic acid intaked Elevated AFP in amniotic fluid and maternal serum AFP and acetylcholinesterase in CSF |
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Anencephaly
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Forebrain anomaly
No brain/skull Malformation of anterior end of neural tube +AFP, polyhydramnios |
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Holoprosencephaly
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forebrain abnormality
cyclopia less separation of hemispheres across midline association with Patau's, FAS, cleft lip/palate |
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Chiari II
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Posterior Fossa Malformation
cerebellar tonsillar herniation through foramen magnum > aqueductal stenosis and hydrocephaly Presents with Syringomyelia, thoraco lumbar myelomeningocele |
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Dandy-Walker
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Posterior Fossa Malformation
enlargement of PF, absent cerebellar vermis, cystic 4th ventricular enlargement > spina bifida and hydrocephalus |
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Syringomyelia
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Central canal enlargment
bilateral pain and temperature loss C8-T1 most common (spinothalamic tract) |
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Cleft lip/Cleft palate
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Lip - failure of maxillary and medial nasal process fusion (primary palate)
Palate - failure of lateral palatine processes, nasal septum and median palatine porcess fusion (secondary palate) occur together frequently but 2 distinct processes |
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Anterior abdominal wall closure defects
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Rostral fold - sternal defects
Lateral fold - Gastroschisis - extrusion of abdominal contents through abdominal folds, NO peritoneal covering Lateral fold - Omphalocele - herniation of abdominal contents into umbilical cord, Peritoneal covering Caudal fold - Bladder exstrophy |
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Tracheoesophageal fistula
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trachea connection to esophagus
blind upper esophagus most common polyhydramnios, failure to pas NG tube into stomach, pneumonitis |
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Congenital Pyloric Stenosis
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Pyloric hypertrophy > obstruction
palpable epigastric "olive" mass nonbilious projectile vomiting at 2 weeks old 1/600, 1st born males most common, sugery is treatment |
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Annular Pancreas
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ventral pancreatic bud encircles duodenum and can cause narrowing
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Pancreas Divisum
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Ventral and Dorsal parts fail to fuse at 8 weeks, duct fusion failure
In normal adult, major drainage through ventral duct In divisum adult, major drainage through dorsal duct similar to fetal drainage |
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Potter's Syndrome
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Malformation of ureteric bud > Bilateral renal agenesis > oligohydramnios
limb and facial deformities, pumonary hypoplasia |
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Horseshoe Kidney
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Fusion of inferior poles. During ascension from pelvis, kidney trapped under IMA and remain low in abdomen. Normal kidney function
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Bicornuate uterus
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Incomplete fusion of paramesonephric ducts > uterine tract abnormalities and infertility
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Penile Abnormalities
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Hypospadias - urethral fold closure failure - inferior/ventral urethral opening (more common). Hypo - below. Fix to prevent UTIs
Epispadias - genital tubercle positioning error - superior/dorsal urethral opening. Assoiciated with exstrophy of bladder. Epi - pee in Eye |
