Organogenesis: D. Development of Eyes and Ears

Question 1

• are crucial for an animal’s survival and well-being
• focused on the different stages of embryonic development

Answer 1

Eye Development

Question 2

• Eye Development In Animals begins with the formation of the ?, a thickening of the ectoderm.
• Appears on either side of the developing brain (forebrain)

Answer 2

optic placode

Question 3

formation of the optic placode is induced by signals from adjacent mesodermal tissues and neural tissue, such?

Answer 3

as Fibroblast Growth Factor (FGF) and Bone Morphogenetic Protein (BMP)

Question 4

Optic placode invaginates to form the?

Answer 4

optic pit

Question 5

Optic pit eventually pinches off from the surface ectoderm to become the ?, a spherical structure that will give rise to the retina and optic nerve.

Answer 5

optic vesicle (or otocyst)

Question 6

Optic vesicle undergoes further invagination to form the ?, a double-layered structure.

Answer 6

optic cup

Question 7

Optic cup outer layer becomes the?

Answer 7

retinal pigment epithelium (RPE)

Question 8

Optic cup inner layer will develop into the?

Answer 8

neural retina

Question 9

Adjacent ectoderm thickens to form?

Answer 9

lens placodes

Question 10

Placodes invaginate to form lens vesicles, which will differentiate into the ? of the eye.

Answer 10

lens

Question 11

crucial for focusing light onto the retina.

Answer 11

lens vesicle

Question 12

• begins to form from the ectoderm and mesoderm.
• becomes a transparent structure that allows light to enter the eye.

Answer 12

Corneal

Question 13

• forms from the mesodermal tissue surrounding the lens and separates the anterior and posterior chambers of the eye.
• regulates the amount of light entering the eye through the pupil.

Answer 13

Iris

Question 14

It develops distinct layers:
o outer nuclear layer (containing photoreceptors)
o inner nuclear layer (containing bipolar and horizontal cells)
o ganglion cell layer (containing cells whose axons form the optic nerve).

Answer 14

Neural retina

Question 15

(containing photoreceptors)

Answer 15

outer nuclear layer

Question 16

(containing bipolar and horizontal cells)

Answer 16

inner nuclear layer

Question 17

(containing cells whose axons form the optic nerve).

Answer 17

ganglion cell layer

Question 18

are sensitive to low light levels

Answer 18

Rods

Question 19

detect color and detail.

Answer 19

Cones

Question 20

• a gel-like substance filling the eye
• begins to form and fill the space between the lens and the retina.

Answer 20

Vitreous Body

Question 21

• the white part of the eye
• develops from mesodermal tissues
  surrounding the optic cup provides structural support and protection

Answer 21

Sclera

Question 22

• reflective layer of tissue located behind the retina of many nocturnal animals, such as cats, dogs, and deer.
• improve vision in low-light conditions
• enhance night vision.

Answer 22

Tapetum Lucidum

Question 23

develops from the ectoderm and mesoderm layers

Answer 23

ear

Question 24

a thickening of the ectoderm, forms on each side of the hindbrain (rhombencephalon) around the 4th week of human embryonic development.

Answer 24

otic placode

Question 25

otic placode is regulated by various signaling pathways, including?

Answer 25

FGF (Fibroblast Growth Factor) and BMP (Bone Morphogenetic Protein).

Question 26

Otic placode invaginates to form the?

Answer 26

otic pit

Question 27

otic pit pinches off from the surface ectoderm to become the?

Answer 27

otic vesicle (or otocyst)

Question 28

Otic vesicles give rise to the?

Answer 28

inner ear structures

Question 29

otic vesicle differentiates into two main parts:

Answer 29

o utricle and saccule o cochlear duct

Question 30

involved in balance

Answer 30

utricle and saccule

Question 31

is responsible for hearing

Answer 31

cochlear duct

Question 32

Otic vesicle also forms the?

Answer 32

endolymphatic sac and ducts

Question 33

otic vesicle elongates and segments to form?

Answer 33

three semicircular canals

Question 34

cochlear duct elongates and coils to form the?

Answer 34

cochlea

Question 35

spiral-shaped structure essential for converting sound vibrations into?

Answer 35

neural signals

Question 36

essential for converting sound vibrations into neural signals.

Answer 36

spiral-shaped structure

Question 37

- developed within the cochlea and the vestibular system (utricle, saccule, and semicircular canals) - have hair-like projections (stereocilia) that detect sound waves and head movements

Answer 37

Hair Cells

Question 38

- surround hair cells and provide structural support - potential to regenerate hair cells in some species ( fish and birds)

Answer 38

Supporting Cells

Question 39

forms from the pharyngeal cleft (first pharyngeal pouch) and lined by endoderm

Answer 39

middle ear cavity

Question 40

middle ear cavity connects to the ? through the Eustachian tube, which helps equalize air pressure.

Answer 40

nasopharynx

Question 41

middle ear cavity connects to the nasopharynx through the ?, which helps equalize air pressure.

Answer 41

Eustachian tube

Question 42

— malleus, incus, and stapes — develop from the cartilaginous structures of the first and second pharyngeal arches. — are essential for transmitting sound vibrations from the eardrum to the inner ear.

Answer 42

middle ear bones (ossicles)

Question 43

- forms from the six auricular hillocks from the first and second pharyngeal arches - fuses to form the external ear's distinctive shape.

Answer 43

Auricle (Pinna)

Question 44

develops from the first pharyngeal cleft and grows inward toward the tympanic membrane (eardrum), which separates the outer ear from the middle ear.

Answer 44

External Acoustic Meatus (Ear Canal)

Question 45

What cells in the cochlea and vestibular apparatus form connections with the auditory and vestibular nerves?

Answer 45

Sensory cells

Question 46

Sensory cells in the cochlea and vestibular apparatus form connections with the?

Answer 46

auditory and vestibular nerves

Question 47

are crucial for processing sound and balance information

Answer 47

Neural pathways

Question 48

Neural pathways are crucial for processing?

Answer 48

sound and balance information