Embryology Final Exam

Front 1

Malformation

Back 1

Defect resulting from intrinsically abnormal developmental process (i.e. chromosomal abnormality)

Front 2

Disruption

Back 2

Defect resulting from extrinsic breakdown/interference (i.e. teratogens)

Front 3

Deformation

Back 3

Abnormal form, shape, or position of a body part due to unusual mechanical forces (i.e. oligohydramnios)

Front 4

Dysplasia

Back 4

Abnormal organization of cells into tissue

Front 5

Club foot

Back 5

Any abnormal positioning of the foot involving the ankle. Attributed to oligohydramnios, possibly.

Front 6

Thalidomide

Back 6

Teratogen, can cause phocomelia (disruption of growth in the progress zone of the limb bud).

Front 7

Anticonvulsants (dilantin, novophenytoin, diphenyl hydantoin)

Back 7

Fetal hydantoin syndrome: craniofacial defects, nail and digital hypoplasia, MR

Front 8

Syndactyly

Back 8

Webbing or osseus fusion of adjacent digits (mutations in BMPs, CRBPs, MSX1 genes)

Front 9

Polydactyly

Back 9

Extra digits (overexpression of Shh, FGFs)

Front 10

Postaxial deletions

Back 10

Mutations in WNT-7a (necessary for normal anteroposterior positioning)

Front 11

Synpolydactyly

Back 11

Mutation in HOXD13

Front 12

Holt-Oram syndrome

Back 12

Mutation in TBX5 - heart-hand syndrome

Front 13

Finger and toe regeneration in children

Back 13

Under age 6, amputation injury of last phalanx (if at interphalangeal joint or through the distal phalanx)

Front 14

Pectinate line

Back 14

Proximal 2/3 of anal canal: endodermal, venous portal system, lymphatics to intestinal trunks (to cisterna chyli), visceral innervation

Distal 1/3 of anal canal: ectodermal, venous caval system, lymphatics by superficial inguinal nodes, somatic innervation

Tells you how cancer or infections would spread from these regions.

Front 15

Omphalocele

Back 15

Intestinal protrusion covered in peritoneum and amnion, due to incomplete return of midgut loop (gastroschisis: herniation not covered in any body wall)

Front 16

Annular pancreas

Back 16

Bifid ventral bud fuses with dorsal bud and obstructs the duodenum

Front 17

Accessory pancreatic duct (of Santorini)

Back 17

Duct from dorsal bud that leads directly into the duodenum

Front 18

Meckel's diverticulum

Back 18

Failure of proximal yolk stalk to degenerate. Located on ileum. Generally ok, but can become inflamed.

Umbilical fistula: if opening to umbilicus persists after birth

Front 19

Volvulus

Back 19

Abnormal rotation of the midgut, can result in necrosis and gangrene (due to obstructed blood flow from the superior mesenteric artery)

Front 20

Aganglionic megacolon

Back 20

Hirschsprung's disease - failure of neural crest to form the myenteric plexus on sigmoid colon and rectum. Results in enlarged colon, abdominal distention, no peristalsis, abnormal fecal retention.

Hypertrophic pyloric stenosis can also result.

Front 21

Canalization

Back 21

Stenosis or atresia can result from abnormal apoptosis within the gut lumen.

Front 22

Abnormal partitioning of the cloaca

Back 22

Failure of the urorectal septum to fuse with the cloacal membrane, resulting in a persistent cloaca and shared opening of urethra and rectum. Fistulas may form connecting rectum to perineum, vagina, or urethra.

Front 23

Abnormal development of ureteric buds

Back 23

Renal agenesis. Sometimes, two buds may result in the production of supernumerary kidneys or bifid kidneys or ureters.

Front 24

Bilateral renal agenesis

Back 24

Oligohydramnios, amniotic band syndrome possible, not compatible with life outside the uterus. Results from failure of induction of the mesonephric duct by the metanephric blastema.

Front 25

Obstruction of ureter, polycystic kidney

Back 25

Persistent older arteries or veins that can constrict and block the ureter, urine backs up in the tubules and loops of Henle.

Front 26

Abnormal connections of the ureters

Back 26

Ectopic ureters at neck of bladder, genital duct, prostatic urethra in males or neck of the bladder or vestibule of the vagina in females.

Front 27

Exstrophy of the bladder

Back 27

Failure of lateral folds to close, revealing the mucosa of the bladder.

Front 28

Epispadia

Back 28

Failure of lateral folds to close resulting in split, exposed urethral groove on dorsal surface of the penis.

Front 29

Urachal cysts, urachal fistula

Back 29

Normal degeneration of the allantois does not occur, resulting in urachal cysts or open fistula. Fistula would allow urine to escape through the umbilicus.

Front 30

SRY, DSS

Back 30

Extra copy of SRY in XX female results in masculinization. Extra copy of DSS in XY male results in feminization.

Front 31

Turner's syndrome

Back 31

Ovarian hypoplasia, ambiguous external genitalia.

Front 32

Klinefelter's syndrome

Back 32

Reduced testicular size, enlarged breasts due to decreased androgens and increase in gonadotropins.

Front 33

PGCs

Back 33

Failure of migration of PGCs to gonadal ridges = gonadal dysgenesis or agenesis.

Front 34

Cryptoorchidism

Back 34

Failure of full descent of testes. If the gubernaculum is attached to the wrong site, testes can be directed to other ectopic locations.

Front 35

Inguinal hernia

Back 35

Portion of intestine extends into the tunica vaginalis, hydrocele formed.

Front 36

Bicornuate and unicornuate uterus

Back 36

Septum that separates fused paramesonephric ducts fails to degenerate. If only one half fails to develop, unicornuate results.

Front 37

Vaginal atresia or agenesis

Back 37

Failure of induction of the uterovaginal primordial to form the vaginal plate

Front 38

Hypospadia

Back 38

Incomplete fusion of urogenital folds resulting in ventrally located urethral opening.

Front 39

Androgen insensitivity sydrome

Back 39

Male psuedohermaphrodite, external female characteristics, abdominal testes, blind vagina

Front 40

Male pseudohermaphrodite

Back 40

Lack of testosterone, MIF in XY individual

Front 41

CAH

Back 41

Female pseudohermaphrodite, enlarged clitoris, fused labia majora. Results from mutations in adrenocortical steroid production, no cortisol, ACTH produced in high quantities, androgens produced.

Front 42

Cleft lip

Back 42

Incomplete fusion of maxillary prominences with the intermaxillary segment.

Median: median nasal prominences
Oblique: lateral nasal prominences
Median, lower: mandibular prominences

Front 43

Macrostomia, microstomia

Back 43

Macro: maxillary and mandibular prominences don't completely fuse laterally
Micro: excessive fusion

Front 44

Cleft palate

Back 44

Anterior: primary palate fails to fuse with lateral palatine processes
Posterior: lateral palatine processes fail to fuse with one another and the nasal septum
Anteroposterior: combination of the above

All that involve soft palate only are considered posterior.

Front 45

Treacher-Collins

Back 45

Underdevelopment of the zygomatic bones, mandible, ears due to abnormal migration of neural crest to the first arch.

Front 46

Pierre-Robin

Back 46

Mandibular hypoplasia, obstructed airway

Front 47

Palpebral coloboma, eyelid coloboma

Back 47

Upper or lower eyelid develops abnormally (latter is associated with Treacher-Collins)

Front 48

DiGeorge syndrome

Back 48

Abnormal development of 3rd and 4th pouches due to a chromosome 22 deletion. Associated with CV defects, immunodeficiency, hypocalcemia (due to parathyroid gland absence).

Front 49

Ankyloglossia

Back 49

"Tongue tie", frenulum extends to the tip of the tongue

Front 50

Pharyngeal cyst, fistula

Back 50

Persistent opening of branchial grooves (2, 3, or 4) or branchial sinus. Pharyngeal fistula is an open communication between the tonsillar sinus and an external opening on the neck.

Front 51

Thyroglossal duct cyst

Back 51

Remnants of the thyroglossal duct that protrude from the neck.

Front 52

Craniopharyngioma

Back 52

Remnants of Rathke's pouch (the hypophysial stalk) that forms a benign tumor - requiring surgery or radiation, followed by HRT

Front 53

Congenital hypothyroidism (Cretinism)

Back 53

Maternal thyroid deficiency that results in fetal thyroid deficiency - defects in skeletal growth, dry skin, wide set eyes, etc. If untreated, MR and dwarfism can result. Treat with thyroid HRT.

Front 54

Crania bifidum

Back 54

Brain may herniate through fontanelles or at the junction with the foramen magnum. May involve meningocele, meningoencephalocele, meningohydroencephalocele (meninges, brain, part of a ventricle).

Front 55

Anencephaly

Back 55

Anterior neuropore fails to close during the 4th wk. Acrania. Meroanenephaly may result if some midbrain and hindbrain remain. Polyhydramnios often accompanies it, fetal after birth.

Front 56

Microcephaly

Back 56

Abnormal (reduced) growth of the cerebrum and cerebellum, cranium still present. Growth of the calvaria due to response to pressure of the growing brain.

Front 57

Craniostenosis

Back 57

Premature fusion of the skull plates, resulting in impaired brain development, deformation of the calvaria.

Scaphocephaly or dolichocephaly: sagittal suture premature closure

Oxycephaly or brachycephaly: coronal or lambdoid premature closure (associated with Apert syndrome).

Plagiocephaly: unilateral premature coronal or lambdoid suture closure.

Trigonocephaly: frontal suture premature closure.

Front 58

Cleidocranial dysostosis

Back 58

Mutation in CBFA1, absent clavicles, poor mineralization of the calvaria bones, affects ossification and development of the teeth.

Front 59

Arnold-Chiari syndrome

Back 59

Displacement of the medulla and part of the cerebellum into the spinal canal, causing hydrocephalus. May result from abnormal development of the posterior fossa, or hypertrophic growth of the cerebellum. May also be associated with spina bifida.

Front 60

Coloboma iridis

Back 60

Problems related to the closure of the optic fissure, a cleft may extend into the ciliary body, retina, choroid, or even the optic nerve.

Front 61

Congenital cataracts

Back 61

Result from defective lens development, can be due to genetic conditions (aniridia, Down, galactosemia) or congenital rubella, toxoplasmosis, syphilis

Front 62

Microphthalmia

Back 62

Small eye due to trisomy 13, aniridia, fetal infection. Eyelids do form.

Front 63

Aniridia

Back 63

Mutation in PAX6, no iris forms.

Front 64

Retinoblastoma

Back 64

Tumor derived from persistent pluripotent cells of the immature retina, white pupil (leukocoria). RB gene is a tumor suppressor gene. Hereditary is bilateral, non-hereditary is unilateral.

Front 65

Cyclopia

Back 65

Failure of proper patterning of the forebrain (associated with BMPs and Shh), incompatible with life.

Front 66

Retrolental fibropasia

Back 66

Oxygen-induced retinopathy - abnormal growth of retinal blood vessels.

Front 67

Persistent iridopupillary membrane

Back 67

Strands of the covering of the developing lens that persist.

Front 68

Conduction deafness

Back 68

Interruption in the passage of sound waves through the ear, due to auricular atresia, absence of the external acoustic meatus, defective middle ear bone development.

Front 69

Abnormal development of the spiral organ of Corti

Back 69

Results from rubella virus exposure.

Front 70

Atresia of external auditory meatus

Back 70

Failure of canalization of the meatal plug, associated with first arch syndromes or second arch defects.

Front 71

Microtia

Back 71

Small disorganized auricle due to inadequate development and fusion of the auricular hillocks.

Front 72

Auricular appendages

Back 72

External skin tags that result from abnormal development of the auricular hillocks - purely cosmetic.

Front 73

Divergence

Back 73

Individual genes that participate in the development of multiple developmental processes or tissues (pleiotropy).

Examples: FGF, Shh, AIS, Kartagener, Fragile X.

Front 74

Convergence

Back 74

Multiple genes control the development of specific structures.

Examples: holoprosencephaly caused by trisomy 13, trisomy 18, deletion of 18p, FAS. Interaction of HoxA-11 and HoxD-11 for radius and ulna.

Front 75

TORCH teratogens

Back 75

Toxoplasma gondii, rubella, cytomegalovirus, herpes simplex.

Others: varicaella, syphilis.

Front 76

Radiation

Back 76

Damage of DNA, free radical formation, heat from a hot tub or sauna increases the risk of spina bifida or brain defects

Front 77

Heavy metals

Back 77

Benzene and mercury linked to Down's

Front 78

Polychlorinated biphenyls (PCBs)

Back 78

Defects in cognitive ability.

Front 79

Vitamin A

Back 79

Inhibits migration and induction of neural crest cells

Front 80

Steroids

Back 80

Can masculinize a female fetus

Front 81

Diethylstilbestrol

Back 81

Increased risk of miscarriage

Front 82

Thyroid hormone

Back 82

MR, dystrophy of bones

Front 83

Tetracyclines

Back 83

Abnormal bone and tooth development

Front 84

Streptomycin

Back 84

Deafness

Front 85

Warfarin

Back 85

Fetal hemorrhage

Front 86

Alcohol

Back 86

FAS - MR, microcephaly, holoprosencephaly, craniofacial abnormalities, hypotelorism, long indistinct philtrum, short palpebral fissures, limb defects, CV defects

Front 87

Smoking

Back 87

Believed to be the single largest cause of SIDS

Front 88

Marijuana

Back 88

THC can cross the placenta, nervous system disorders, deficits in learning, memory, behavior

Front 89

Cocaine

Back 89

Retarded growth, stiff limbs, hyperirritability, crib deaths, deficits in learning.

Front 90

Isotretinoin (Accutane)

Back 90

Facial defects, i.e. cleft lip, palate.