Eye and Ear

1. Eye 1) The wall of eyeball ① Fibrous tunic: DCT ---cornea: ---sclera: DCT ---corneal limbus(corneoscleral limbus) Cornea: /anterior 1/6 of fibrous tunic, transparent, bulges slightly anteriorly /connect with sclera

/five layers: corneal epithelium: i. stratified, squamous non-keratinising epithelium ii. 5-6 layers of regular arranged cells iii. basal cells have remarkable regenerating ability iv. rich in nerve terminal

anterior limiting lamina: i. a clear uniform membrane, um thick ii. contain collagenous fibrils and matrix iii. cannot regenerate

corneal stroma: corneal propria i. constitute 90% of corneal thickness ii. composed of layers of collagenous fibrils iii. keratocyte: similar to fibroblast iv. matrix, no BV

posterior limiting lamina: i. a clear homogenous membrane, 5-10 um thick ii. consists of collagenous fibril and matrix corneal endothelium: i. simple squamous epi. ii. EM: mito, pinocytotic vescles, Golgi and RER iii.Active function of transporting, synthesizing and secreting protein

* transparency of the cornea: due to absence of BV non-pigmented epi, regular organization of collagen fibrils maintenance of hydration of ground substance

② Vascular tunic(uvea): LCT with BV and melanocytes ---iris ---ciliary body ---choroid

③ retina: ---pigment epithelium: outerest layer simple low columnar epi: -culomnar cell: thin, long processes at apical surface -round or ovoid N -EM: SER, Golgi, rough round or ovoid pigment granules

-function: i. protect visual cell ii. involve in replace of membranous disc iii. store vitamin A and involve in the synthesis of rhodopsin

---visual cell: photoreceptor cell /cell body: /inner process: form synapse with bipolar cell and horizontal cell /outer process: -outer segment: contain membranous disc -inner segment: contain mito, RER, Golgi and MT

/rod cell: -110,000, ,000,000 -deep-stained N -outer process: cylindrical -outer segment: membranous disc-invagination of cell membrane but separated with cell membrane(exfoliated and ingested by pigment cell) -rhodopsin(visual purpke)= 11- cisretinal(retinene) + opsin -inner process: spherule(end in a terminal expansion) -feel dim light

/cone cell: -6,500,000-7,000,000 -large N, paler-stained -outer process: conical -outer segment: membranous disc, not separated, no exfoliation of disks -iodopsin(photopsin)= 11-cisretinal + opsin(different) -inner process: pedicle -feel blight light(red-558nm, green-531nm, blue- 419nm)

---bipolar cell: /large N /contain RER,mito and Golgi /dendrite: synapse with photoreceptor and horizontal neuron /axon: form synapse with dendrite of ganglion cell /classification: -rod bipolar cell -midget bipolar cell -flat bipolar cell

---ganglion cell: /multipolar neuron: /dendrite: synapse with bipolar, amacrine cell and interplexiform cell /axon: make up optic nerve /classification: midget ganglion cell and diffuse ganglion cell

---interneurons: /located in layer of bipolar cell /horizontal cell, amacrine cell, interplexiform cell ---radial neuroglia cell: Muller cell /neuroglial cell /thin and long cell, with ovoid, deep-stained N /processes: end at outer limiting membrane and inner limiting membrane /function: supporting, protecting, nourishing and insulating function

Under LM: retina can be divided into ten layers i. layer of pigment epithelium: pigment epithelial cell ii. layer of rods and cones iii. outer limiting membrane: outer processes of Muller cell iv. outer nuclear layer: N of visual cells v. outer plexiform layer: inner process of visual cell, dendrites of bipolar cell and processes of horizontal cell

vi. inner nuclear layer: cell body of bipolar cell, horizontal cell, amacrine cell and interplexiform cell and Muller cell vii.inner plexiform layer: axon of bipolar cell, dendrites of ganglion cell, processes of amacrine cell and interplexiform cell viii. layer of ganglion cells: cell body of ganglion cell ix. layer of optic fibers: axons of ganglion cell x.inner limition membrane: formed by connection each other of inner processes of Muller cells

* macula lutea: /definition: a small area of retina at posterior polar of retina, contains a yellow pigment and is non-vascularised, so called yellow spot /3mm in D /central fovea: shallow depression, 1.5mm in D /thinnest retina: 0.1mm /contain only cone cell, no rod cell /one visual cell connects with one bipolar cell, and one bipolar cell forms synapse with one ganglion cell /have most clear vision

* papilla of optic nerve: optic disc /1.5 mm in D /3 mm medial to macula lutea /place where the optic nerve leave out /no photoreceptors: so called blind spot

2. Ear ---the external ear ---the middle ear ---the inner ear

1) inner ear: labyrinth ---osseous labyrinth: a system of canals and cavities in compact bone the vestibule semicircular canal cochlea

---membranous labyrinth: usually lined by simple squamous epi. except: membrane semicircular canal: crista ampullaries saccule and utricle: macula utriculi and macula sacculi cochlear duct: spiral organ

-triangular in cross-section -three walls: i. roof: vestibular membrane ii. outer wall: stratified columnar epi. with BV distributed- stria vascularis(secrete endolymph) and spiral ligament iii. floor: osseous spiral lamina and membranous spiral lamina – basilar membrane

a. crista ampullaris: ---supporting cell: /columnar, with basal ovoid nucleus, rest on basal lamina /microvilli, granules: lipid-liked and glycosaminoglycan granules

---hair cell: /amongat supporting cell /pear-shaped: short neck and globular base /has about stereocilia and one kinocilium(embedded in cupula) /terminal of peripheral process of neuron of vestibular nerve ganglion distributed at basal portion of hair cell ---cupula: gelatinous mass of mucopolysaccharide substance ---function: receptors for kinetic balance, feel angular acceleration or deceleration of the head

b. macula utriculi and macula sacculi: macula acustica ---supporting cell ---hair cell: stereocilia and one kinocilium --- otolithic membrane: gelatinous mucopolysaccharide substance containing small crystalline bodies of calcium carbonate ---function: receptors of static balance, feel linear acceleration or deceleration and change in position of the head

c. spiral organ: Corti organ ---supporting cell: pillar cell: -two rows: inner and outer pollar cell: tall, columnar in shape, -inner tunnel

phalahgeal cell: -inner phalangeal cell: one row, is situated next to inner pillar cell -outer phalangeal cell: 3-5 rows, lateral to the outer pillar cells -tall columnar cells rest on basilar membrane -phalangeal process: enclosed the low part of hair cell

---hair cell: -inner hair cell: a row of pear-shaped cell, supported by inner phalangeal cell -outer hair cell: 3-5 rows, supported by outer phalangeal cell - “ V ” or “ W ” shaped-arranged stereocilia on free surface ---peripheral processes of neuron of spiral ganglion distribute at basal portion of hair cell ---tectorial membrane ---auditory string: 2000, located in basilar membrane, collagen-liked thin filament ---function: receptor of sound