Question 1

What are the key protein constituent(s)of the lens?&#10;A) Melanin&#10;B) Crystallins&#10;C) Keratins

Accepted Answer

Crystallins are the key protein constituents of the lens.

Question 2

Which is the most frequent genetic syndrome that affects the retina?&#10;A) Osteoporosis-pseudoglioma syndrome&#10;B) Leber congenital amaurosis syndrome&#10;C) Retinitis pigmentosa&#10;D) Familial exudative vitreoretinopathy&#10;E) Norrie disease

Accepted Answer

B

Question 3

Protanopes lack which cell type?&#10;A) S cones&#10;B) M cones&#10;C) L cones&#10;D) Rods

Accepted Answer

Protanopes lack functioning L cones, which are responsible for detecting long wavelengths of light (red). This results in difficulty distinguishing shades of red and green.

Question 4

Researchers have shown that the various regions of the developing eye are specified by different transcription factors whose expression is induced by the adjacent tissues.Chx10 is one such factor that is required for the development of the neural retina.What growth factor regulates its expression?

A) Shh
B) TgfBeta
C) Fgf
D) Egf
E) Vegf

Accepted Answer

The transcription factor Chx10 is necessary for the specification of bipolar cells in the neural retina.

Question 5

Goldenhar syndrome is characterized by a spectrum of defects.What eye abnormality is the cardinal finding of this syndrome?&#10;A) Epicanthal folds&#10;B) Cryptophthalmos&#10;C) Epibulbar dermoids&#10;D) Distichiasis&#10;E) Ocular telangiectasia

Accepted Answer

The cardinal finding in Goldenhar syndrome is the presence of epibulbar dermoids, which are raised, white-yellow nodules on the surface of the eye. Although the syndrome can also be associated with other eye abnormalities, such as microphthalmia or coloboma, epibulbar dermoids are the most common ocular feature.

Question 6

Researchers have shown that the various regions of the developing eye are specified by different transcription factors whose expression is induced by the adjacent tissues.Chx10 is one such factor that is required for the development of the neural retina.What growth factor regulates its expression?

A) Shh
B) TgfBeta
C) Fgf
D) Egf
E) Vegf

Accepted Answer

The growth factor that regulates the expression of Chx10 is Fgf (fibroblast growth factor). Fgf signals from the optic vesicle induce Chx10 expression in the overlying surface ectoderm, which then induces the formation of the neural retina.

Question 7

Branchio-oto-renal syndrome,characterized by kidney and hearing defects,is due to mutation of which gene?&#10;A) EYES ABSENT HOMOLOG 1(EYA1)&#10;B) EYES ABSENT HOMOLOG 4 (EYA4)&#10;C) POU4F3&#10;D) CONNEXIN 26&#10;E) FGF8

Accepted Answer

Branchio-oto-renal syndrome is caused by mutation in the EYA1 gene on chromosome 8q13.3. This gene provides instructions for making a protein that is involved in the development of several organs and tissues including the kidneys, ears, and throat. Mutations in this gene disrupt the normal development of these organs and tissues, leading to the characteristic features of the syndrome.

Question 8

Mutations in the gene encoding the FOXC2 transcription factor would be expected to cause which anomaly?&#10;A) Epicanthal folds&#10;B) Cryptophthalmos&#10;C) Epibulbar dermoids&#10;D) Distichiasis&#10;E) Ocular telangiectasia

Accepted Answer

Mutations in the FOXC2 gene are associated with lymphedema-distichiasis syndrome, where one of the primary features is distichiasis, or the abnormal growth of eyelashes from the meibomian glands.

Question 9

Coloboma results from failure of which development event?&#10;A) Eye induction&#10;B) Differentiation of the photoreceptors&#10;C) Regression of the hyaloid artery&#10;D) Closure of the optic fissure&#10;E) Formation of the eyelids

Accepted Answer

Coloboma results from failure of closure of the optic fissure during embryonic development. This leads to a gap in the optic disc, which can cause visual impairment.

Question 10

Which growth factor signaling pathway initiates retinal differentiation in the fovea?&#10;A) Shh&#10;B) Wnt&#10;C) Notch&#10;D) Bmp&#10;E) Fgf

Accepted Answer

The Fgf (Fibroblast Growth Factor) signaling pathway is known to play a crucial role in initiating retinal differentiation, including in the fovea, by promoting the development of photoreceptor cells and other retinal neurons.

Question 11

During retinal differentiation,the various cell types differentiate in sequence.Which cell type is the last to be born?&#10;A) M&#252;ller&#10;B) Ganglion&#10;C) Amacrine&#10;D) Bipolar&#10;E) Rod&#10;F) Cone

Accepted Answer

The answer of During retinal differentiation,the various cell types differentiate...

Deck 20: Development of the Eyes