Organogenesis: D. Development of Eyes and Ears Flashcards
- are crucial for an animal’s survival and well-being
- focused on the different stages of embryonic development
Eye Development
- Eye Development In Animals begins with the formation of the ?, a thickening of the ectoderm.
- Appears on either side of the developing brain (forebrain)
optic placode
formation of the optic placode is induced by signals from adjacent mesodermal tissues and neural tissue, such?
as Fibroblast Growth Factor (FGF) and Bone Morphogenetic Protein (BMP)
Optic placode invaginates to form the?
optic pit
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.
optic vesicle (or otocyst)
Optic vesicle undergoes further invagination to form the ?, a double-layered structure.
optic cup
Optic cup outer layer becomes the?
retinal pigment epithelium (RPE)
Optic cup inner layer will develop into the?
neural retina
Adjacent ectoderm thickens to form?
lens placodes
Placodes invaginate to form lens vesicles, which will differentiate into the ? of the eye.
lens
crucial for focusing light onto the retina.
lens vesicle
- begins to form from the ectoderm and mesoderm.
- becomes a transparent structure that allows light to enter the eye.
Corneal
- 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.
Iris
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).
Neural retina
(containing photoreceptors)
outer nuclear layer
(containing bipolar and horizontal cells)
inner nuclear layer
(containing cells whose axons form the optic nerve).
ganglion cell layer
are sensitive to low light levels
Rods
detect color and detail.
Cones
- a gel-like substance filling the eye
- begins to form and fill the space between the lens and the retina.
Vitreous Body
- the white part of the eye
- develops from mesodermal tissues
surrounding the optic cup provides structural support and protection
Sclera
- 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.
Tapetum Lucidum
develops from the ectoderm and mesoderm layers
ear
a thickening of the ectoderm, forms on each side of the hindbrain (rhombencephalon) around the 4th week of human embryonic development.
otic placode
otic placode is regulated by various signaling pathways, including?
FGF (Fibroblast Growth Factor) and BMP (Bone Morphogenetic Protein).
Otic placode invaginates to form the?
otic pit
otic pit pinches off from the surface ectoderm to become the?
otic vesicle (or otocyst)
Otic vesicles give rise to the?
inner ear structures
otic vesicle differentiates into two main parts:
o utricle and saccule
o cochlear duct
involved in balance
utricle and saccule
is responsible for hearing
cochlear duct
Otic vesicle also forms the?
endolymphatic sac and ducts
otic vesicle elongates and segments to form?
three semicircular canals
cochlear duct elongates and coils to form the?
cochlea
spiral-shaped structure essential for converting sound vibrations into?
neural signals
essential for converting sound vibrations into neural signals.
spiral-shaped structure
- 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
Hair Cells
- surround hair cells and provide structural support
- potential to regenerate hair cells in some species ( fish and birds)
Supporting Cells
forms from the pharyngeal cleft (first pharyngeal pouch) and lined by endoderm
middle ear cavity
middle ear cavity connects to the ? through the Eustachian tube, which helps equalize air pressure.
nasopharynx
middle ear cavity connects to the nasopharynx through the ?, which helps equalize air pressure.
Eustachian tube
— 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.
middle ear bones (ossicles)
- forms from the six auricular hillocks from the first and second pharyngeal arches
- fuses to form the external ear’s distinctive shape.
Auricle (Pinna)
develops from the first pharyngeal cleft and grows inward toward the tympanic membrane (eardrum), which separates the outer ear from the middle ear.
External Acoustic Meatus (Ear Canal)
What cells in the cochlea and vestibular apparatus form connections with the auditory and vestibular nerves?
Sensory cells
Sensory cells in the cochlea and vestibular apparatus form connections with the?
auditory and vestibular nerves
are crucial for processing sound and balance information
Neural pathways
Neural pathways are crucial for processing?
sound and balance information
