Embryo - Eye & Ear Flashcards
Congenital aniridia
(absence of iris) It is a rare anomaly due to an arrest of development at the rim of the optic cup.
Congenital aphakia
(absence of lens) is a rare anomaly due to failure of lens placode to form.
Congenital cataract
Lens appears white and opaque at birth. Maternal rubella infections cause this anomaly.
Persistent hyaloid artery
Sometimes remnants of the hyaloid canal or artery can be seen as floats which may interfere with vision.
What are the 3 parts of the ear?
-
External Ear
- Pinna of auricle
- External auditory meatus
-
Middle Ear
- Auditory ossicles
- Muscles
- Tensor tympani
- Stapedius
-
Internal Ear (1st to dev)
- Membranous labrynth
- Bony labrynth
What is Coloboma of the iris?
Keyhole pupil
- Results do to FAILURE of closure of retinal fissure!
Detachment of retina
Intra-retinal space
- Fusion btw NEURAL (inner) & PIGMENT (outer) layer = not very strong
- provides easy plane of cleavage for detachment
- Detachment can occur secondarily during development OR after birth
- result from blow to the eye
Iris Development
- Develops from the anterior rim of the optic cup
- which overlaps the lens
What gives rise to pupillary muscles?
Neuroectodermal cells
How do Ciliary Bodies develop?
- From the circular portion of the optic cup
- between the developing retina & iris
Note:
- Adjoining mesenchyme gives rise to the ciliaris muscle
Development of lens
Lens develops from the lens vesicle
(surface ectoderm)
What are the structures of the developing eye?
Microphthalmia
Small eye due to arrested development.
May be caused by rubella infection.
Anophthalmia
Complete absence of eye. Eyelids are present.
May be associated with other craniocerebral defects.
Cryptophthalmos
Hidden eye
- occurs due to a failure of development of palpebral fissure.
- The eye ball is small or defective
- lies beneath the skin.
