Embryo Exam 2

Front 1

1. Probe patency

Back 1

After birth, when lung circulation begins and pressure in the left atrium increases, the valve of the oval foramen is pressed against the septum secundum, obliterating the oval foramen and separating the left and right atria.

In about 20% of cases, fusion of the septum primum and septum secundum is incomplete and a narrow cleft remains between the two atria.

Does not allow shunting of blood.

Front 2

2. Atrial septal defects

Back 2

Left to right shunting of blood.

-Can involve a persistent ostium secundum (ostium secundum defect) in which a large opening between the left and right atria exists.
-Common atrium
-Defect in endocardial cushions
-Defect involving sinus venosum
-Includes probe patency
-Caused by excessive cell death and resorption of septum primum or by inadequate development of septum secundum.

Front 3

3. Ventricular septal defects

Back 3

Left to right shunting of blood (if defect is large enough)

Typically involves the membranous portion of the septum

Small defect may close spontaneously

Caused by abnormalities in partitioning of the conotruncal region

Front 4

4. Transposition of the great vessels

Back 4

Septum that normally divides the aorta and pulmonary trunk does not form properly

Occurs when the conotruncal septum fails to follow its normal spiral course.

Aorta originates from right ventricle and pulmonary artery originates from left ventricle.

Usually accompanied by an open ductus arteriosus.

Front 5

5. Dextrocardia

Back 5

Heart lies on the right side of thorax instead of the left; caused b/c the heart loops to the left instead of the right.

May coincide with situs inversus.

Can lead to immobile cilia and sterility

Front 6

6. Tetralogy of Fallot

Back 6

Right to left shunting of blood!

1) Pulmonary stenosis
2) Ventricular septal defect
3) Right ventricular hypertrophy
4) Dextroposition of the aorta

Front 7

7. Persistent truncus arteriosus

Back 7

Conotruncal ridges fail to fuse and descend toward the ventricles.

Accompanied by an IV septal defect

Truncus gets blood from both ventricles

Front 8

8. Cor tiloculare biventriculare

Back 8

Complete absence of the atrial septum

Abnormal flow from right atrium to left atrium

Probe patency is very common

Front 9

9. Valvular stenosis of pulmonary artery or aorta

Back 9

The semilunar valves are fused for a variable distance

Front 10

10. Aortic valvular stenosis

Back 10

fusion of the thickened valves may be so complete that only a pinhole opening remains

size of aorta itself is usually normal

Front 11

11. Aortic valvular atresia

Back 11

Occurs when fusion of the semilunar aortic valves is complete

Usually accompanied by an open ductus arteriosus which can deliver blood to the otherwise blocked aorta.

Front 12

12. Patent ductus arteriosus

Back 12

Defects that cause large differences between aortic and pulmonary pressures may cause increased blood flow thru the ductus, preventing normal closure

Front 13

13. Coarctation of aorta

Back 13

Aortic lumen below the origin of the left subclavian artery is significantly narrowed.

Caused by an abnormality in the media of the aorta.

Collateral circulation btw proximal and distal parts of the aorta is established by way of large intercostal and internal thoracic arteries.

Characterized by femoral pulse occurring after radial pulse (usually other way around) and RIB NOTCHING

Front 14

14. Double aortic arch

Back 14

the right dorsal aorta persists btw the origin of the 7th intersegmental artery and its junction w/the left dorsal aorta

a valvular ring surrounds the trachea and esophagus and commonly compresses these structures, causing difficulties in breathing and swallowing.

Front 15

15. Interrupted aortic arch

Back 15

caused by obliteration of the 4th arch on the left side

usually combined w/an abnormal origin of the right subclavian artery

ductus arteriosus remains open and subclavian arteries are supplied w/blood of low oxygen content

Front 16

16. Double IVC

Back 16

occurs when the left sacrocardinal vein fails to lose its connection w/the left subcardinal vein

Front 17

17. Absence of IVC

Back 17

arises when the right subcardinal vein fails to make its connection w/the liver and shunts its blood directly into the right supracardinal veins.

The azygos vein takes over the IVC's function

Usually associated w/other heart malformations

Front 18

18. Holt-Oram syndrome

Back 18

Characterized by preaxial (radial) limb abnormalities and atrial septal defects.

Defects in the muscular portion of the IV septum may also occur.

Front 19

19. Premature closure of the foramen ovale

Back 19

Leads to massive hypertrophy of the right atrium and ventricle and underdevelopment of the left side of heart

Usually fatal - death occurs shortly after birth

Front 20

20. Ostium primum defect

Back 20

Endocardial cushions in the AV canal partially fuse; result is a defect in the atrial septum but the IV septum is closed.

Usually combined with a cleft in the anterior leaflet of the tricuspid valve

Front 21

21. Tricuspid atresia

Back 21

Involves obliteration of the right AV orifice

Characterized by the absence or fusion of the tricuspid valves.

Always associated with:
1. Patent foramen ovale
2. Ventricular septal defect
3. Underdevelopment of the right ventricle
4. Hypertrophy of the left ventricle.

Front 22

22. Cantrell Pentalogy

Back 22

A spectrum of abnormalities involving thorax and abdomen

Involves:
1. Cleft sternum
2. Ectopia cordis
3. Omphalocele
4. Diaphragmatic hernia
5. Ventricular septal defect or Tetralogy of Fallot

Front 23

23. DiGeorge sequence

Back 23

A pattern of malformations that have their origin in abnormal neural crest development.

These children have facial defects, thymic hypoplasia, parathyroid dysfunction, and cardiac abnormalities involving the outflow tract, such as persistent truncus arteriosus and tetralogy of Fallot

Front 24

24. Ventral wall defects

Back 24

Results from a failure of body folding or incomplete development of body wall structures

Can include:
1. Cleft sternum
2. Ectopia cordis
3. Omphalocele

Front 25

25. Structures that contribute to the formation of the diaphragm

Back 25

1. Septum transversus (forms central tendon)

2. Pleuroperitoneal membranes (contacts the septum transversum)

3. Paraxial mesoderm - from body wall (forms smooth muscle of diaphragm

4. Dorsal mesentery - from the esophagus (forms the left and right crura)

Front 26

26. Congenital diaphragmatic Hernia

Back 26

a common malformation

Results from failure of the pleuroperitoneal membrane to close the pericardioperitoneal canal.

Most common (85-90%) is on the left as the left canal is larger and closes later

High rate of mortality b/c of pulmonary dysfunction

Front 27

27. Esophageal hernial (Hiatial)

Back 27

Esophagus fails to lengthen sufficiently and the stomach is pulled up into the esophageal hiatus through the diaphram

Due to a defect in the right crus of the diaphram or a short esophagus

Front 28

28. Parasternal hernia

Back 28

Results from a deficit btw the sternal and costal heads of the diaphragm

May go undetected until child is several years old

A small, peritoneal sac containing intestinal loops may enter the chest btwn the sternal and costal sides of the diaphragm.

Front 29

29. Esophageal atresia/Tracheoesophageal fistula

Back 29

Atresia results from abnormal partitioning of the esophagus and trachea (tracheoesophageal septum) and involves a narrowing or closure of the esophagus

Can occur w/ or w/o a fistula

Most esophageal fistulas involve a proximal esophageal pouch and a distal esophagus that communicates w/the airway

Is associated w/polyhydraminos if there is an esophageal obstruction b/c embryo cannot drink thru airway.

Front 30

30. Primary retroperitoneal organs

Back 30

kidneys

ureters

bladder

aorta

IVC

Front 31

31. Secondary retroperitoneal

Back 31

duodenum (parts 2 & 3)
ascending and descending colon
rectum
gallbladder
pancreas
liver

Front 32

32. Intraperitoneal organs

Back 32

stomach
spleen
part 1 of duodenum
jejunum
ileum
transverse and sigmoid colons

Front 33

33. Meckel's diverticulum

Back 33

Results from a persistence of the vitelline duct

-Affects 2% of the population
-Found 2 ft proximal to the ileocecal valve
-About 2 inches long
-Contains 2 types of ectopic tissue (stomach and pancreas)

Can cause ulceration, bleeding, or even perforation; can also result in a vitelline cyst.

Front 34

34. Pyloric stenosis

Back 34

occurs when the cicular and longitudinal musculature of the stomach in the pylorus region hypertrophies.

Passage of food is obstruction, resulting in projectile vomiting.

Front 35

35. Hirschspung's disease (megacolong)

Back 35

failure of the neural crest cells to migrate to the caudal 1/3 of large intestine

results in the absence of the parasympathetic ganglia in the myenteric plexus needed for distension of gut and peristalsis

Front 36

36. Omphalocele (umbilical hernia)

Back 36

herniation of abdominal viscera through an enlarged umbilical ring.

May include liver, small and large intestines, stomach, spleen, or gallbladder, are covered by amnion.

Caused by a failure of the bowel to return to the body cavity from its physiological herniation.

Front 37

37. Gastroschisis

Back 37

Intestines herniate into umbilical cord after returning to the abdominal cavity

Involves a rupture of amnion.

Occurs lateral to the umbilicus, usually to the right.

Front 38

38. Fistulas involving the cloaca

Back 38

involves improper formation of the urorectal septum

If the urorectal septum does not extend far enough caudally, openings of the hindgut shifts anteriorly leading to an opening of the hindgut into the urethra or vagina.

Front 39

39. Atresias

Back 39

interruption of the gut tube

Esophagus: milk is not curdled
Gastric: milk is curdled
Duodenum: bile

Front 40

40. Annular pancreas

Back 40

Right portion of the ventral bud of the pancreas migrates along its normal route but the left migrates in the opposite direction.

Duodenum is surrounded by pancreatic tissue and causes constriction or complete obstruction.

Front 41

41. Malrotation of gut

Back 41

May result in twisting of the intestine (volvulus) and a compromise of the blood supply.

Colon and cecum are the first portions of the gut to return from the umbilical cord and they settle on the left side of the abdominal cavity.

The later returning loops then move more and more to the right, resulting in a left sided colon

Front 42

42. Apple peel atresia

Back 42

Atresia is in proximal jejunum, and the intestine is short, with the portion distal to the lesion coiled around a mesenteric remnant.

Front 43

43. Metanephric mesoderm gives rise to:

Back 43

1. Bowman's capsule
2. Proximal convoluted tubule
3. Loop of Henle
4. Distal convoluted tubule

Consists of simple cuboidal epithelium

Front 44

44. Polycystic kidney

Back 44

Numerous cysts form on kidney

Kidney becomes very large and renal failure occurs

Front 45

45. Renal agenesis

Back 45

occurs when the ureteric bud fails to reach the metanephric mesoderm

Associated with oligohydraminos

Incompatible with life if bilateral

Front 46

46. Pelvic kidney

Back 46

as the kidney ascends toward the abdomen, they pass btw the two umbilical arteries

occasionally, one gets blocked and remains in the pelvic cavity

suprarenal gland forms separately so it's not affected.

Front 47

47. Horseshoe kidney

Back 47

during development the metanephric mesoderm fuses while in the pelvis

the normal ascent is stopped by the inferior mesenteric artery due to the shape of the fused kidney

Front 48

48. Bifid ureter

Back 48

occurs when the ureteric bud divides prematurely

Front 49

49. Ectopic ureter

Back 49

opening of the ureter into the vagina, urethra, or vestibule.

results from two ureteric buds. one of the buds usually is normal but the other moves down together with the mesonephric duct.

Front 50

50. Wilms' tumor

Back 50

cancer of the kidneys that usually affects children by 5 years of age

Front 51

51. Denys-Drash syndrome

Back 51

consists of renal failure, psudohermaphrodism, and Wilms' tumor.

Front 52

52. Potter sequence

Back 52

Anuria, oligohydraminos, hypoplastic lungs secondary to the oligohydraminos.

In 85% of the cases, other severe defects including absence or abnormalities of the vagina, uterus, vas deferens and seminal vesicles occur. Cleft lip and palate, brain abnormalities, and cardiac problems also occur

Front 53

53. Exstrophy of the cloaca

Back 53

a severe ventral body wall defect in which migration of mesoderm to the midline is inhibited and the tail (caudal) fold fails to progress

As a result, a thin layer of ectoderm ruptures and includes exstrophy ofthe bladder, imperforate anus, opmphalocele, and spinal defects

Front 54

54. Exstrophy of the bladder

Back 54

a ventral body wall defect where the mucosa of the bladder is exposed to the exterior

may be caused by the lack of mesodermal migration into the region btw the genital tubercle and the umbilicus

Front 55

55. Urachal fistula and cyst

Back 55

Caused by the persistence of the intraembryonic portion of the allantois.

May cause urine to drain from the umbilicus

If only a portion of the alantois persists, results in a urachal cyst.

Front 56

56. Hydrocele

Back 56

processus vaginalis doesn't close and accumulates fluid btwn the parietal and visceral layers of the tunica vaginalis

Front 57

57. Cryptorchidism

Back 57

one or both testes fail to descend

caused by decreased androgen production

testes fail to produce mature spermatozoa

Front 58

58. Mesonephric ducts give rise to:

Back 58

1. Epididymis
2. Ductus deferens
3. Ejaculatory duct
4. Seminal vesicle

Front 59

59. Paramesonephric ducts give rise to:

Back 59

1. Uterine tubes
2. Uterus
3. Superior part of vagina

Front 60

60. Turner's syndrome

Back 60

chromosomal anomaly (45 XO)

Germ cells degenerate after reaching the gonadal ridge; ovaries do not form but rather ovarian streaks form

Genitalia are female, but infantile

Short stature, high arched palate, shield like chest, cardiac and renal anomalies, and inverted nipples

Front 61

61. True hermaphrodites

Back 61

extremely rare; 70% are 446, XX, and there is usually a uterus. External genitalia are ambiguous or predominately female, and most are raised as females

Front 62

62. Female pseudohermaphrodites

Back 62

most commonly caused by CAH or exposure of a female fetus to excessive levels of androgens; have a 46,XX chromosome complement but excessive production of androgens masculinizes the external genitalia; clitoral hypertrophy and partial fusion of the labia majora.

Front 63

63. Male pseudohermaphrodites

Back 63

46,XY

Reduced production of androgenic hormones and MIS are responsible for this.

Internal and external sex characteristics vary considerably

Front 64

64. Swyer syndrome

Back 64

AKA XY female gonadal dysgenesis

Individuals appear to be normal females but do not menstruate and do not develop secondary sex characteristics at puberty

Front 65

65. Klinefelter syndrome

Back 65

have 47,XXY or 46,XXXY

Are male, but have small testes, tall stature, and long lower limbs and gynocomastia

Front 66

66. Androgen insensitivity syndrome

Back 66

Have 46,XY but appear as normal females

Vagina ends in a blind pouch and the uterine tubes are absent or rudimentary.

Testes usually located in abdomen or lodged in inguinal canal

Results from a resistance to the action of testosterone b/c of a defect in the androgen receptor

Front 67

67. Duplications of the uterus

Back 67

result from a lack of fusion of the paramesonephric ducts in a local area or throughout their normal line of fusion.

Can include double uterus (uterus didelphys), uterus arcuatus, and uterus bicornis (in which the uterus has two horns enterine a common vaginal)

Front 68

68. Double vagina

Back 68

If the sinovaginal bulbs fail to fuse or do not develop at all, a double vagina or atresia of the vagina, respectively, results.

Front 69

69. Hypospadias/Epispadias

Back 69

Hypospadias: fusion of the urethral folds is incomplete around the vental side of the penis

Epispadias (rare) the urethral meatus is found on the dorsum of the penis

Front 70

70. Placenta accreta

Back 70

placenta adheres to the myometrium

Front 71

71. Placenta percreta

Back 71

placenta penetrates the full thickness of the myometrium and fails to separate from the uterine wall

Front 72

72. Dizygotic twins

Back 72

fraternal, results from multiple ovulations caused by high levels of FSH

Front 73

73. Monozygotic twins

Back 73

identical, arise from single ovum fertilized by a single sperm

may be related to hatching form the zona pellucida

Front 74

74. Fetal papyraceus

Back 74

vanishing twin

death of one fetus may result form resorption or mummification of dead fetus

Front 75

75. Twin transfusion syndrome

Back 75

Occurs in 5% of monochorionic monozygotic pregnancies.

One twin receives most of the blood flow and flow to the other is compromised.

Front 76

76. Conjoined twins

Back 76

partial splitting of the primitive node and streak may result in formation of conjoined twins.

Classified as thoracopagus (thorax joined), pygopagus (lower back), and craniopagus (head).