Term
| What is the function of Sonic Hedgehog? |
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Definition
at base of limbs in zone of polarizing activity. Patterning along anterior-posterior axis
ex: duplication of SHH causes 2 sets of toes on 1 foot
Does digit identity |
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Term
| What does the Wnt-7 gene do? |
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Definition
| At apical ectodermal ridge, for org along dorsal-ventral axis. |
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Term
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Definition
At apical ectodermal ridge. Stim's mitosis of underlying mesoderm allowing for lengthening of limbs
Absence = complete loss of limb (amelia)
Disruption of FGF signalling = meromelia (absence of part of limb) |
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Term
| What does the homeobox gene do? |
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Definition
Segmental organization in a craniocaudal direction.
No hox = phocomelia (short, poorly formed limbs) |
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Term
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Definition
| Helps separate digits (apoptosis of tissue b/w them) |
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Term
| What is the rule of 2's for the 2nd week of development? |
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Definition
2 germ layers (bilaminar disk)" epiblast and hypoblast
2 cavities (amniotic and yolk sac)
2 components to placents: cytotrophoblast and syncytiotrophoblast |
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Term
| What is the rule of 3's for the 3rd week of development? |
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Definition
| 3 germ layers (gastrula): ectoderm, mesoderm and endoderm |
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Term
| What is the rule of 4's for the 4th week of development? |
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Definition
| 4 heart chambers, 4 limb buds grow |
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Term
| When is the fetus most susceptible to teratogens? |
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Definition
| Weeks 3-8 (embryonic period - organogenesis) |
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Term
| At what week does a fetus have genitalia w/ male/female characteristics? |
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Definition
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Term
| What are the alar and basal plate? What do they do? |
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Definition
Alar = dorsal = sensory
Basal = ventral = Motor
Same orientation as the spinal cord!! |
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Term
| What things are derivatives of the surface ectoderm? |
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Definition
| Adenohypophysis (Rathke's pouch), lens of eye, epithelial linings of oral cavity, sensory organs of ear and olfactory epithelium, epidermis, salivary, sweat and mammary glands |
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Term
| What things are derivatives of the neuroectoderm? |
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Definition
Brain (neurohypophysis, CNS neurons, oligodendrocytes, astrocytes, ependymal cells, pineal gland), retina and spinal cord.
CNS! |
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Term
| What things are derivatives of the neural crest? |
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Definition
ANS, DRG, cranial nerves, celiac ganglion, Schwann cells, pia and arachnoid, bones of skull, odontoblasts (PNS AND NON-NEURAL STRUCTURES NEARBY)
PLUS chromaffin cells of adrenal medulla, parafollicular cells of thyroid, melanocytes and aorticopulmonary septum
Also: odonto = teeth "Think CREST toothpaste" |
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Term
| What things are derived from the endoderm? |
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Definition
| Gut tube epithelium and derivatives (lungs, liver, pancreas, thymus, parathyroid, thyroid follicular cells) |
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Term
| What things are mesodermally derived? |
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Definition
Muscle, bone, CT, serous linings, spleen, cardiovasc structures, lymphatics, blood, bladder, urethra, vagina, eustachian tube, kidneys, adrenal CORTEX, skin dermis, testes, ovaries
AND Notochord (induces ectoderm to form neuroectoderm (neural plate)) |
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Term
| What does the notochord become postnatally? |
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Definition
| Nucleus pulposus of intervertebral disk |
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Term
| What syndrome is associated with mesodermal defects? |
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Definition
VACTERL:
Vertebral defects, Anal atresia, Cardiac defects, Tracheo-Esophageal fistula, Renal defects, Limb defects (bone and mm) |
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Term
| What is the difference b/w malformation and deformation? |
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Definition
Malformation = INTRINSIC disruption (occurs during embryonic period)
Deformation = extrinsic disruption (occurs AFTER embryonic period) |
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Term
| What is the difference b/w agenesis, hypoplasia and aplasia? |
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Definition
Agenesis = absent primordial tissue
Hypoplasia = incomplete organ dev (primordial tissue present)
Aplasia = absent organ despite present primordial tissue (DOESN'T MATURE) |
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Term
| What defects can alkylating agents cause as a teratogen? |
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Definition
| Absence of digits, multiple anomalies |
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Term
| What effects can Lithium have on the fetus? |
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Definition
| Ebstein's anomaly (atrialized right ventricle) |
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Term
| What effect can maternal diabetes have on a fetus? |
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Definition
| Caudal regression syndrome (anal atresia to sirenomelia) |
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Term
| What effects can Valproate have on a fetus? |
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Definition
| Inhibition of intestinal folate absorption |
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Term
| What effects can vitamin A excess have on a fetus? |
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Definition
| extremely high risk for spontaneous abortions and birth defects (cleft palate, cardiac abnormalities) |
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Term
| What are the findings of a fetus with Fetal Alcohol Syndrome? |
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Definition
Dev. retardation, microcephaly, holoprosencephaly, facial abnl, limb dislocation, heart and lung fistulas
Mechanism: inhibition of cell migration |
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Term
| When are the chorion and amnion formed? |
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Definition
Chorion = day 3
Amnion = day 8 |
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Term
| What layers are the cytotrophoblast and syncytiotrophoblast? |
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Definition
Cyto = INNER layer of chorionic villi (Cyto makes Cells)
Syncytio = OUTER layer (secretes hCG!) |
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Term
| What are the umbilical arteries and veins derived from? |
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Definition
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Term
| What does the urachus derive from? What does it connect to? |
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Definition
Forms from the allantois
Connects b/w the bladder and yolk sac |
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Term
| What does the vitelline duct connect? |
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Definition
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Term
| What is Meckel's diverticulum? |
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Definition
| Partial closure of vitelling fistula, w/ patent portion attached to the ileum. May have ECTOPIC GASTRIC MUCOSA --> melena and periumbilical pain |
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Term
| The Truncus Arteriosus forms what? What is it derived from? |
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Definition
| Neural crest migration (truncal and bulbar ridges spiral and fuse to form aorticopulmonary septum) |
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Term
| What is the order of septum formation in the heart? |
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Definition
Muscular ventricular septum forms (w/ an intervent foramen)
AP septum fuses w/ muscular to form membranous septum (closes foramen)
Growth of endocardial cushions separates atria from vent's (contributes to atrial sep and membranous portion of intervent septum) |
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Term
What is the valve of the foramen ovale formed from?
What causes a patent foramen ovale? |
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Definition
the remaining portion of the septum primum
Patent FO caused by excessive resorption of septum primum/secundum |
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Term
| What is the atrial septum derived from? |
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Definition
| Septum secundum and septum primum fusion |
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Term
| Where does fetal erythropoiesis occur and when? |
|
Definition
Yolk sac (3-8 weeks)
Liver (6-30 wk)
Spleen (9-28 wk)
Bone marrow (28 wk onward) |
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Term
| What causes closure or opening of a PDA? |
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Definition
Closure = indomethicin
Open = Prostaglandins
Increased O2 leads to decrease in prostaglands, causing closure when baby begins breathing |
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Term
What does the prosencephalon form?
Mesencephalon?
Rhombencephalon? |
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Definition
Prosencephalon = Telencephalon (cerebrum) and Diencephalon (Thalami, etc)
Mesencephalon = midbrain
Rhombencephalon = Metencephalon (pons and cerebellum) and myelencephalon (medulla) |
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Term
| What are the findings w/ amniocentesis w/ failure of fusion of neuropores? |
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Definition
Elevated AFP in amniotic fluid and maternal serum
Elevated AFT + acetylcholinesterase in CSF |
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Term
| What is Chiari II and Dandy-Walker? |
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Definition
Chiari II = cerebellar tonsillar herniation thru foramen magnum w/ aqueductal stenosis and hydrocephaly (syringomyelia and thoracolumbar myelomeningocele)
Dandy-Walker = lg posterior fossa, absent cerebellar vermis w/ cystic enlargement of 4th vent. --> hydrocephalus and spina bifida |
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Term
| What are the aortic arch derivatives? |
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Definition
1st = MAXillary a
2nd = Stapedial a and hyoid a (2nd = stapedial)
3rd = common Carotid and prox internal Carotid (C = 3rd letter of alphabet)
4th = L - aortic arch, R - prox R subclavian a
6th = prox pulmonary aa and ductus arteriosus on L (Pulmonary and pulm-systemic shunt) |
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Term
| What is the branchial apparatus? |
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Definition
Clefts = Ectoderm
Arches = mesoderm
Pouches = endoderm
CAP covers outside from inside: Clefts/Arches/Pouches (ecto-->endo) |
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Term
| What branchial cleft develops into the external auditory meatus? |
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Definition
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Term
| What are the nerves associated w/ each branchial arch? |
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Definition
1 = V2 and V3 (chewing)
2 = VII
3 = IX (stylopharyngeous)
4th = CN X (sup laryngeal = swallowing)
6th = CN X (recurrent laryngeal = speaking) |
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Term
| What are the muscles associated with each branchial arch? |
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Definition
1 = muscles of mastication
2 = muscles of facial expression, stapedius, stylohyooid and post belly digastric
3 = stylopharyngeus
4 = pharyngeal constrictors (crycothyroid, levator veli palatini)
6 = intrinsic mm of larynx BUT cricothyroid |
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Term
| What are the derivatives of the branchial pouches? |
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Definition
1 = middle ear cavity, eustachian tube, mastoid air cells
2 = epith lining of palatine tonsil
3 = INF parathyroid + thymus
4 = SUPERIOR parathyroids |
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Term
| What is MEN 2A? What is the mutation assoc w/ it? |
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Definition
| mut of RET (neural crest cells) Adrenal medulla (pheo), Parathyroid tumor (3/4th pharyngeal pouches), Parafollicular cells (medullary thyroid cancer) --> assoc w/ 4/5th pharyngeal pouches |
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Term
| The parts of the tongue are from what branchial arches? |
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Definition
1st = ant 2/3 (CN V3 and VII)
3rd/4th = post 1/3 (taste via CN IX, extreme post via X) |
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Term
| What tumor is associated with Rathke's pouch? |
|
Definition
Craniopharyngioma
Cholesterol crystals, calcifications |
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Term
| What is the normal remnant of the thyroglossal duct? |
|
Definition
Foramen cecum
Thyroglossal duct cyst in midline neck ==> will move w/ swallowing (vs persistent cervical sinus leading to branchial cleft cyst in LATERAL neck) |
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Term
| What is duodenal atresia, jejunal, ileal and colonic atresia due to? |
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Definition
Duodenal = failure to recanalize (Downs)
Jejunal, ileal, colonic = vascular accident (apple peel atresia) |
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Term
| When does the midgut herniate and return to the abdominal cavity? |
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Definition
6th week = herniates thru umbilical ring
10th week = returns to abd cavity + ROTATES around SMA |
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Term
| What is the difference b/w Gastroschisis and Omphalocele? |
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Definition
Gastroschisis = extrusion of abd contents thru abd folds (NOT covered by peritoneum)
Omphalocele = persistence of herniation into umbilical cord, IS COVERED by peritoneum |
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Term
| What is the pancreas derived from? How does its development occur? |
|
Definition
From FOREGUT
Dorsal and ventral buds contribute to pancreatic head, uncinate process and main pancreatic duct.
Dorsal bud = everything else (body, tail, isthmus, and accesory pancreatic duct) |
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Term
| How is the spleen different from the rest of the "gut"? |
|
Definition
MESODERMAL (rest of gut is endodermal)
Is from dorsal mesentary but is supplied by a of foregut (CELIAC a) |
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Term
| What is the development of the kidney (in general)? |
|
Definition
| Pronephros --> mesonephros (1st trimester kidney) --> metanephros (begins in 5th week but continues formation thru 32-36 wks) |
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Term
| What are the derivatives of the metanephros? |
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Definition
Ureteric bud = ureter, pelvises and calyces and collecting ducts (canalized by 10th wk)
Metanephric mesenchyme = interaction w/ ureteric bud induces formation of glomerulus and renal tubules to DCT (proximal structures) |
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Term
| What is the most common site of obstruction (hydronephrosis) in the fetus? |
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Definition
Uteropelvic junction w/ kidney
Last to canalize |
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Term
|
Definition
|
|
Term
| What does the mesonephric duct form? |
|
Definition
| Seminal vesicles, Epididymis, Ejaculatory duct and Ductus deferens (internal structures BUT prostate) |
|
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Term
| What does the paramesonephric duct form? |
|
Definition
Female internal structures = fallopian tube, uterus and upper 1/3 vagina
(lower 2/3 from UROGENITAL SINUS) |
|
|
Term
| How does a bicornuate uterus form? |
|
Definition
Incomplete fusion of paramesonephric ducts
Assoc w/ infertility |
|
|
Term
| What does the genital tubercle form? |
|
Definition
| Glans penis/Glans clitoris, Corpus cavernosum and spongiosum/vestibular bulbs |
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|
Term
| What does the urogenital sinus form? |
|
Definition
Glands!
Bulbourethral glands/Greater vestibular glands(Bartholin) and prostate/urethral and paraurethral glands (Skene) |
|
|
Term
| What does the urogenital folds form? |
|
Definition
Ventral shaft of penis (urethra)/Labia MINORA
defect assoc w/ hypospadias |
|
|
Term
| What does the labioscrotal swelling form? |
|
Definition
|
|
Term
| What is the difference b/w hypospadias and epispadias? |
|
Definition
Hypo = failure of urethral FOLDS to close
Epi = faulty positioning of genital TUBERCLE |
|
|
Term
| What are the female and male remnants of the Gubernaculum? |
|
Definition
Ovarian lig + round Lig
Anchors testes w/in scrotum |
|
|
Term
| What are the remnants of the processus vaginalis (evagination of peritoneum)? |
|
Definition
| Obliterated in female Forms tunica vaginalis in male |
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