M&n Week 4: Embryology

Front 1

During which week of development does the thyroid gland form as a small, solid mass of endoderm?

Back 1

4th week

Front 2

From which anatomical structure does the thyroid gland form?

Back 2

Foramen cecum

Front 3

When does the thyroglossal duct dissolve?

Back 3

End of 5th week

Front 4

When does the thyroid gland reach its final position?

Back 4

7th week

Front 5

During which weeks of development does the thyroid gland begin to function?

Back 5

10th to 12th week

Front 6

During development of the thyroid, what structure connects the descending gland to the foramen cecum?

Back 6

Thyroglossal duct

Front 7

Normally, the only remnant of the thyroglossal duct is the...?

Back 7

Foramen cecum

Front 8

Which structures does the 3rd pharyngeal pouch form?

Back 8

1. Thymus gland
2. Inferior parathyroid glands

Front 9

The superior parathyroid glands arise from which pharyngeal pouch?

Back 9

4th pharyngeal pouch

Front 10

The thyroid's point of evagination is marked by which structure?

Back 10

Foramen cecum

Front 11

By which week of development is the esophagus, stomach, and proximal duodenum visibly divided?

Back 11

5th week

Front 12

The hepatic, cystic, and dorsal and ventral pancreatic diverticula bud from which structure?

Back 12

Proximal duodenum

Front 13

What happens if the transcription factor, Isl1, is lost in pancreatic tissue?

Back 13

Pancreatic mesenchyme is almost completely lost

(Isl1 = insulin gene enhancer protein-1)

Front 14

What happens if Fgf10 is lost in pancreatic tissue?

Back 14

Hypoplastic dorsal and ventral pancreatic buds

Front 15

What happens of Pbx1 is lost in pancreatic tissue?

Back 15

Severe hypoplasia of dorsal pancreas and loss of acinar development

Front 16

During which week of development do the dorsal and ventral pancreatic buds fuse?

Back 16

6th week

Front 17

Which pancreatic bud gives rise to the uncinate process?

Back 17

Ventral pancreatic bud

Front 18

Occasionally, the pancreas forms a complete ring encircling the duodenum, a condition known as...

Back 18

Annular pancreas

Front 19

How may an annular pancreas be problematic?

Back 19

May cause gastrointestinal obstruction
(Duodenal atresia)

Front 20

Which molecular signal may restrict pancreatic size?

Back 20

Shh
(Sonic hedgehog)

Front 21

What type of molecular signaling plays an important role in mediating pancreatic cell specification?

Back 21

Notch signalling

Front 22

Which transcription factor is important for the development of pancreatic endocrine, intestinal enteroendocrine, and gastric endocrine cells?

Back 22

Ngn3
(neurogenin 3)

Front 23

One downstream target of Notch signaling in the pancreatic endoderm is...?

This transcription factor downregulates which other transcription factor?

Back 23

Notch ---(+)--> Hes1 ----(-)----> Ngn3

Front 24

Cells in which Ngn3 expression is repressed by Notch signalling become part of the ________ pancreas.

Back 24

Exocrine

Front 25

What are the first endocrine cells to form within the pancreatic endoderm?

Back 25

Glucagon-synthesizing cells

Front 26

Does Ngn3 signalling preferentially drive alpha or beta cell specification in the pancreas?

Back 26

Alpha

Front 27

Which transcription factors act downstream with Ngn3 to promote beta cell specification?

Back 27

Nkx2.2 and Nkx6.1

Front 28

What is the result of absent Nkx2.2 transcription factor in pancreatic tissue?

Back 28

No insulin gene activation => Failure of b-cell differentiation

Front 29

What is the result of absent Nkx6.1 in pancreatic tissue?

Back 29

Small number of beta cells are generated, but failure to maintain or increase their numbers during subsequent development

(Nkx6.1 transcription factor specifically expressed in adult beta-cells)

Front 30

What is the result of absent Pax4 in pancreatic tissue?

Back 30

Complete lack of both alpha and beta cells

Front 31

Which transcription factor plays an important role in mediating the expression of differentiated endocrine products of the islet (i.e. insulin)?

Back 31

NeuroD1

Front 32

What is the result of absent NeuroD1 in pancreatic tissue?

Back 32

Normal b-cell production initially, but gradual decline by apoptosis

Front 33

Mutations in NeuroD1 is associated with which 2 conditions?

Back 33

1. Maturity-onset diabetes of the young (MODY)
2. Type II diabetes

(inadequate production of insulin due to gradual decline of b-cell population)

Front 34

T or F

The number of islet cells that develop in the pancreas is generally set during fetal life.

Back 34

TRUE

Front 35

During the second trimester, the fetal cortical layer grows rapidly in size and begins secreting _________, a hormone converted by the placenta to ________, which is essential for maintaining pregnancy.

Back 35

DHEA (dehydroepiandrosterone)
Estradiol

Front 36

When does the fetal cortex regress and the zona glomerulosa, fasciculata, and reticularis form?

Back 36

By the second postnatal month

Front 37

Mutations in DAX1 gene can lead to what clinical condition?

Back 37

Congenital adrenal hypoplasia