Usmle Step 1 Fa Embryology-General

Front 1

Describe fct of following genes:
(a) sonic hedgehog
(b) wnt-7
(c) FGF gene
(d) homeobox gene

Back 1

(a) produced at base of limbs in zone of polarizing activity. Involved in patterning along anterior posterior
axis
(b) produced at apical ectodermal ridge. Necessary for proper organization along dorsal-ventral axis
(c) produced at apical ectodermal ridge. Stimulates mitosis of underlying mesodern to lengthen limbs
(d) involved in segmental organization

Front 2

Fetal landmarks:
Day 0
Within wk1
Within wk2
Within wk3
Within wk3-8
Within wk 4
Within wk 8
Within wk 10

Back 2

-Day 0: fertilization forming zygote
-Within wk1: Implantation as blastocyst
-Within wk2: Bilaminar disk (epiblast/hypoblast)
-Within wk3: Gastrulation (3 germ layers form-ectoderm, mesoderm, endoderm). Primitive streak, notocord, neural plate form.
-Within wk3-8: Neural tube formed.
-Within wk 4: Heart begins to beat. Upper and lower limb buds form.
-Within wk 8: Fetal movement (looks like a baby)
-Within wk 10: Genitalia have male/female characteristics.

Front 3

Ectopic Pregnancy
(1) Most common form
(2) Most common abdominal site
(3) Risk factors
(4) Clinical signs

Back 3

(1) ampulla of uterine tube
(2) rectouterine pouch (Pouch of Douglas)
(3) Endometriosis, PID, tubular pelvic surgery, exposure to diethylstilbestrol (DES)
(4) Abnormal or brisk uterine bleed, acute abdomen, missed period, +hCG, culdocentesis showing intraperitoneal blood, +sonogram

Front 4

hCG
(1) fct
(2) how long does the corpus luteum need to persist to support pregnancy?
(3) low hCG may indicate:
(4) high hCG may indicate:

Back 4

(1) Stimulates production of progesterone by corpus luteum
(2) 8 wks
(3) ectopic pregnancy; spontaneous abortion
(4) hydatidiform mole; multiple pregnancy; gestational trophoblastic neoplasia

Front 5

Embryological derivatives of:
(1) Ectoderm
(2) Mesoderm
(3) Endoderm

Back 5

(1) Ectoderm
-Surface ectoderm: adenohypophysis (anterior pituitary); lens of eye; epithelial lining of oral cavity, ear, eye, and nose; epidermis; salivary, sweat, and mammary glands
-Neuroectoderm: Neural tube (CNS neurons, olidgodendrocytes, astrocytes, ependymal cells, pineal gland, neurohypophysis); retina; spinal cord
-Neural crest: ANS; DRG; CN's; celiac ganglion; enterochromaffin cells (adrenomedulla); parafollicular cells of thyroid; Schwann cells; pia and arachnoid; bones of skull; odontoblasts; laryngeal cartilage; aorticopulmonary septum
(2) Mesoderm: Muscle; CT; serous membranes; bone; cartilage; blood; lymph; CV organs; adrenal cortex; urogenital structures; spleen; kidney and ureter; dura mater
(3) Endoderm:
-Epithelial parts: GI tract, tonsils, thymus, pharynx, larynx, trachea, bronchi, lungs, urinary bladder, urethra, tympanic cavity, auditory tube, and pharyngeal pouches
-Parenchyma: liver, pancreas, thyroid follicular cells, parathyroids, glands of GI tract, submandibular and sublingual glands.

Front 6

Common mesodermal defects

Back 6

VACTERL
-vertebral defects
-anal atresia
-CV defects
-tracheoesophageal fistula
-renal defects
-limb defects

Front 7

Caudal dysplasia (sirenomelia)

Back 7

Constellation of syndromes ranging from minor lesions of lower vertebrae to complete fusion of lower limbs. Result of abnormal gastrulation and associated w/VACTERL.

Front 8

Teratogen effect on fetus:
(1) alcohol
(2) ACEI
(3) Cocaine
(4) Diethylstilbestrol
(5) Iodide (lack or excess)
(6) VitA (excess)
(7) Thalidomide
(8) Smoking (nicotine, CO)
(9) X rays, anticonvulsants
(10) Warfarin
(11) Tetracyclines
(12) Alkylating agents
(13) aminoglycosides
(14) Folate antagonists

Back 8

(1) alcohol: Leading cause of birth defects and mental retardation; FAS
(2) ACEI: Renal damage
(3) Cocaine: Abnormal development and addiction; placental disruption
(4) Diethylstilbestrol: vaginal clear cell adenocarcinoma
(5) Iodide (lack or excess): congenital goiter or hypothyroidism
(6) VitA (excess): high risk for spontaneous abortion and birth defect (cleft palate, CV defect)
(7) Thalidomide: limb defects (flipper limbs)
(8) Smoking (nicotine, CO): preterm labor, placental problems, IUGR, ADHD
(9) X rays, anticonvulsants: multiple anomalies
(10) Warfarin: bone deformities, hemorrhage, abortion
(11) Tetracyclines: discolored teeth
(12) Alkylating agents: absence of digits, multiple anomalies
(13) aminoglycosides: CNVIII toxicity
(14) Folate antagonists: neural tube defects

Front 9

Sacrococcygeal teratoma

Back 9

Tumor arising from primitive streak which normally degenerates and disappears. Contains various types of tissue due to derivation from pluripotent cells. More common in females. Usually becomes malignant during infancy and must be removed by 6mos.

Front 10

Chorion develops on day?
Amnion develops on day?

Back 10

Chorion formed day 3
Amnion formed 8

Front 11

Velamentous placenta

Back 11

Umbilical vessels abnormally travel through amniochorionic membrane before reaching placenta proper. Can rupture and cause fetal hemorrhage and death.

Front 12

Alpha Fetoprotein
(1) when does it appear?
(2) elevated AFP associated with?
(3) reduced AFP associated with?

Back 12

(1) Fetal albumin (AFP) appears at 14-18w
(2) Neural tube defects, omphalocele (fetal serum leaking into amniotic fluid), esophageal and duodenal atresia
(3) Down syndrome

Front 13

Vitelline fistula

Back 13

B/w umbilicus and terminal ileum; results in fecal discharge (meconium)

Front 14

Urachal fistula

Back 14

b/w umbilicus and bladder; results in urinary discharge

Front 15

Fetal-postnatal derivatives
(1) umbilical vein
(2) Umbilical arteries
(3) ductus arteriosus
(4) ductus venosus
(5) foramen ovale
(6) allantois
(7) notochord

Back 15

(1) umbilical vein: ligamentum teres hepatis (contained in falciform ligament)
(2) Umbilical arteries: medial umbilical ligaments
(3) ductus arteriosus: ligamentum arteriosum
(4) ductus venosus: ligamentum venosum
(5) foramen ovale: fossa ovalis
(6) allantois: median ligament
(7) notochord: nucleus pulposus of intervertebral disk

Front 16

Location of fetal erythropoiesis at various stages in fetal development

Back 16

Yolk sac (3-8wk)
Liver (6-30wk)
Spleen (9-28wk)
Bone marrow (28wk+)

Front 17

Hgb synthesis at various stages in fetal development

Back 17

Delta2episolon2 (by yolk sac)
Alpha2gamma2 (by liver)
Alpha2beta2 (bone marrow)