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Esophagus > Foregut development > Flashcards

Foregut development Flashcards

1
Q

fetal period starts at ?

A. 8th week of gestation
B. 7th week of gestation
C. 10th week of gestation
D. 9th week of gestation

A

Ans D -

the fetal period starts at the ninth week of gestation and ends at birth.

Shackleford 7e Pg 32.

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2
Q

percursor of the mucosa is the ?

A. Endoderm
B. Ectoderm
C. Mesoderm
D. Both A and C

A

Ans A - Endoderm

the precursor tissue of the mucosa, the endoderm is recognizable by the 8th day of embryonic period, when its cells rapidly form the lining of the yolk sac.

Shackleford 7e Pg 32.

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3
Q

Mesoderm first appears around the

A. 10th day of gestation
B. 5th day of gestation
C. 15th day of gestation
D. 18th day of gestation

A

Ans C - 15th day of gestation

Shackleford 7e Pg 32.

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4
Q

segmentation of the paraxial mesoderm into somites occurs in

A. Cranial/Caudal direction
B. Caudal/Cranial direction
C. Simultaneously in all segments
D. random pattern

A

Ans A -
Cranial/Caudal direction.

Shackleford 7e Pg 32.

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5
Q

The C shape of the embryonic disc is attained by

A. 15-20 days
B. 20-25 days
C. 25-30 days
D. 30-35 days

A

Ans C - 25-30 days.
Rapid formation of somites curves the straight embryonic disk ventrad into C shape between days 25 to 30.

Shackleford 7e Pg 32.

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6
Q

Extra-embryonic yolk sac disappears by

A. 8th week
B. 10th week
C. 12th week
D. 14th week

A

Ans C - 12th week

Compression of the yolk sac divides the yolk sac into

  1. Extra-embryonic portion, which regresses and disappears at about 12th week
  2. an intra-embryonic portion, which represents the developing digestive tract and its accessory glands.

Shackleford 7e Pg 33.

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7
Q

tracheal bud appears during the ?

A. 4th week
B. 5th week
C. 6th week
D. 7th week

A

Ans A - 4th week.

Shackleford 7e Pg 33.

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8
Q

lung tissue and distinct rings of cartilage in tracheal tissue can be seen by -

A. 4th week
B. 5th week
C. 6th week
D. 7th week

A

Ans D - 7th week

Shackleford 7e pg 33.

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9
Q

Hypobranchial eminence gives rise to the?

A. Aryepiglottic folds
B. crioid catilage
C. Thyroid cartilage
D. Epiglottis

A

Ans D - Epiglottis.

Shackleford 7e Pg 33.

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10
Q

the definite topographic relationships of the esophagus are attained by

A. 4th week
B. 5th week
C. 6th week
D. 7th week

A

Ans D - 7th week (18-22mm CRL) stage.

Shackleford 7e Pg 36

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11
Q

which of the following is not true?

A. the stomach rotates 90 degree during fetal life.
B. there is no evidence of esophageal or gastric mechanical rotation
C. developing cardia and pylorus are definitely fixed.
D. there is asymmetric growth of the stomach wall which gives stomach its typical shape

A

Ans A - Stomach rotates 90 degree.

the primitive stomach appears below the septum transversum in the 6mm-7mm CRL stage.
The greater gastric curvature grows at a much faster rate than the wall of the opposite right side, which is to become the lesser curvature.
The asymmetric growth of the gastric wall feigns positional changes of the stomach. Traditional teaching of visceral embryology, therefore often includes the stomach in the events of bowel rotation. In reality however there is no evidence at all of any esophageal or gastric mechanical rotation.

The growth will also give rise to the gastric fundus, the cardiac angulation and the EGJ. (Pg 38)

Shackleford 7e Pg 37

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12
Q

Largest portion of the diaphragm is derived from the

A. Septum transversum
B. dorsal mesenchyme of the esophagus
C. dorsolateral body wall tissue
D. Pleuroperitoneal membranes

A

Ans - A - Septum transversum

Shackelford 7e Pg 38.

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13
Q

The central tendon of the diaphragm is derived from?

A. Septum transversum
B. Dorsal mesenchyme of the esophagus
C. Dorsolateral body wall tissue
D. Pleuroperitoneal membrane

A

Ans A - Septum transversum.

the largest portion derives from the septum transversum, which has already fused with the ventral mesenchyme of the esophagus in the 7mm embryo. It eventually forms the central tendon of the diaphragm.

Shackleford 7e Pg 38.

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14
Q

Crura of the diaphragm are derived from the ?

A. Septum transversum
B. Dorsal mesenchyme of the esophagus
C. Dorsolateral body wall tissue
D. Pleuroperitoneal membrane

A

Ans B - Dorsal mesenchyme of the esophagus

the Medial portion derives from the dorsal mesenchyme of the esophagus and gives rise to the crura of the diaphragm. The crura are formed at a point where the septum transversum and pleuroperitoneal membrane fuse.

Shackleford 7e Pg 38.

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15
Q

The peripheral muscular diaphragm originates from ?

A. Septum transversum
B. Dorsal mesenchyme of the esophagus
C. Dorsolateral body wall tissue
D. Pleuroperitoneal membrane

A

Ans - C - dorsolateral body wall tissue

Shackleford 7e Pg 38.

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16
Q 
The largest portion of the primitive diaphragm is formed by the ? 
A. Septum transversum
B. Dorsal Mesenchyme of the esophagus
C. Dorsolateral body wall tissue
D. Pleuroperitoneal membrane
A

Ans D - pleuroperitoneal membrane

What is initially the largest portion of the primitive diaphragm eventually forms the small intermediate muscular portion of the diaphragm. It is derived from the pleuroperitoneal membranes at the point where they have fused with the dorsal mesenchyme of the esophagus and septum transversum.

Shackleford 7e Pg 38.

17
Q

the apparent descent of the diaphragm is caused by ?

A. rapid growth of dorsal body of the embryo as opposed to the slowly growing pericardium
B. rapid growth of the dorsal mesenchyme of the esophagus
C. increased pressure from the rapidly growing intra-abdominal contents
D. None of the above

A

Ans A - rapid growth of the dorsal body of the embryo as opposed to the slowly growing pericardium causes an apparent descent of the diaphragm.

Shackleford 7e Pg 38.

18
Q

The diaphragm attains its final position at the level of the L1 vertebra by ?

A. 4th week IUL
B. 5th Week IUL
C. 6th week IUL
D. 7th week IUL

A

Ans D - 7th week IUL.

the diaphragm is complete and opposite the thoracic vertebra by the 6th week of IUL. By the end of the 7th week it attains it final position opposite the first lumbar vertebra.

The future diaphragm can already be easily identified by its distinct musculature at the 12-15mm CRL stage.

Shackleford 7e Pg 38.

19
Q

vacoules are most conspicuous during what period of embryonic development?

A. 10-14 mm CRL
B. 14-22 mm CRL
C. 20-24 mmCRL
D. 6-12mm CRL

A

Ans B - 14-22mm CRL

At the 12mm CRL stage, thin walled hollow spaces appear in the proliferating epithelium.

When the embryo is 6 weeks old and has attained 13-14 mm CRL the spaces form different sized cellular vacoules.

They become most conspicuous in the 14-22 mm CRL stage.

Shackleford 7e Pg 41.

20
Q

Which of the following statements is True?

A. Vacoules are the largest and most numerous at the gastric end of the esophagus

B. Vacoules do not develop in the mucosa of the trachea.

C. Vacoulisation is an indicator of cell death and contains lysate.

D. vacoules completely disappear by 28mm CRL

A

Ans C -

A - they are smaller and less frequent in the upper portion of the esophagus but largest and most numerous near the tracheal bifurcation followed by those at the junction into the stomach.

B. Small circular vacoules are found in far smaller number in the mucosa of the trachea, but never in the gastric mucosa.

C. vacoulisation is an indicator of cell death. Many of the larger vacoules contain lysate (cytolytic content)

D. vacoules rupture and discharge their content into the lumen. At a stage of 32mm CRL (3rd month) the vacoules have disappeared, except that very occasionally small ones have been observed till 75mm CRL stage (Late 12th week)

Shackleford 7e Pg 41.

21
Q

the most likely cause for the congenital tracheo-esophageal fistula and esophageal atresia is ?

A. failure of recanalisation
B. vascular injury
C. congenital growth defect of the esophagus or trachea or both
D. defect in pinching off the trachea.

A

Ans C - Congenital growth defect of the esophagus or trachea.

Downward growth of the tracheal bud is documented in topical anatomic and scanning electron microscope studies.
These studies contradict the misleading concept initiated in 1887 by His who taught that the trachea pinches off the primitive foregut by means of wall folding.
Although this claim has never been substantiated, it is still wrongly transmitted as one of the causes of esophageal atresia.
Different factors were regarded to cause esophageal atresia, such as failure of the growth process of the trachea from the esophageal tube, or by epithelial occlusion caused by lack of recanalisation of the esophageal tube following the vacoulisation period.
However differences in growth rates secondary to genetic defects or teratogenic agents appear more likely to produce the defect.

Shackleford 7e Pg 33, 42.

Esophagus (7 decks)

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