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Main page | Structure | Departments | Department of Histology and Embryology | Materials for students | Modul 2 | EAR

EAR. (=E).
Anatomically E. is composed of 3 parts: 1) Outer E., 2) Middle E., 3) Inner E.
INNER E. contains 3 types of tubular components: 1) Cochlear duct, 2) Semicircular duct, 3) Saccule and Utricle. Each tubule contains proper TISSUE SENSORY ZONE. COCHLEAR duct has 3 walls: a) Lateral wall – is stria vascularis, b) Medial wall – is vestibular (or Reissners) membrane, c) Lower wall – is basilar membrane. It is place for location of sensory zone, named organ of CORTI (or organ of HEARING).
ORGAN of CORTI (or organ of hearing) is composed of:
  1. HAIR SENSORY EPITHELIAL cells,
  2. Supporting epithelial cells,
  3. Inner tunnel,
  4. TECTORIAL membrane.
  5. Afferent nerve fibres of  cochlear nerve.
There are 2 types of hair sensory cs: A) Outer hair sensory cs. It are CYLINDRICAL cs with apical stereocilia. B) Inner hair sensory cs. It are FLASK-shaped cs with apical stereocilia. Nerve fibres of cochlear nerve form synaptic junction with basal surface of hair cs. Hairs’ means location of STEREOCILIA on apical surface. Stereocilia – are modified microvilli.Funct.: Hair cs (and organ of CORTI, as sensory zone) transform energy of sound waves into nerve impulse, providing sense of HEARING.
Injury of HAIR cs in organ of Corti leads to DEAFNESS.
Supporting epithelial cells in organ of Corti include:
  1. Inner and outer phalangeal cs, locating beneath hair cs. It have long phalangeal process.
  2. Inner and outer pillar cs. It form wall of inner tunnel. Tunnel contains ENDOLYMPH and afferent nerve fibres of cochlear nerve.
Organ of BALANCE (vestibular apparatus):
It contains 2 tissue sensory zones:
  1. CRISTAE AMPULLARES (of semicircular duct)
  2. MACULAE (of saccule and of utricle).
MACULAE are composed of:
  1. HAIR SENSORY EPITHELIAL cells,
  2. Supporting  epithelial cells,
  3. OTOLITHIC membrane.
  4. Afferent nerve fibres of cochlear nerve.
There are 2 types of hair sensory cs:
  1. Type 1 hair sensory cs. It are FLASK-shaped cs with 2 types of apical SPECIAL organelles: a) short non motile stereocilia and b) single LONG k i n o c i l i u m. Kinocilium – is motile cilium.
  2. Type 2 hair sensory cs. It are CYLINDRICAL cs with same 2 apical special organelles.
Stereocilia and kinocilium are embedded in gelatinous OTOLITHIC membrane. Membr. is composed of  glycoproteins and crystals known as OTOLITHS (calcium carbonate). Funct.: Hair sensory cs (and MACULA, as sensory zone) transform energy of LINEAR movements, GRAVITY and VIBRATION into nerve impulse, providing perception of all these irritations.
CRISTA AMPULLARIS is composed of:
  1. HAIR SENSORY EPITHELIAL cells,
  2. Supporting  epithelial cells (WITHOUT differentiation on types),
  3. CUPULA gelatinosa,
  4. Afferent nerve fibres of cochlear nerve.
There are 2 types of hair sensory cs in crista amullaris:
  1. Type 1 hair sensory cs. and
  2. Type 2 hair sensory cs
Both  types have SAME characteristic, as in macula.
Stereocilia and kinocilium of hair cs are embedded in CUPULA gelatinosa. Funct.: Hair sensory cs (and CRISTA AMPULLARIS , as sensory zone) transform energy of ANGULAR movements into nerve impulse,    providing perception of this irritation.
Organ of OLFACTION (is located in olfactory epithelium of nasal cavity) is composed of: 1) OLFACTORY RECEPTOR cs (=ORC), 2) Tall sustentacular cs, 3) Short basal cs ORC is BIPOLAR NEURON (compare: in organ of Corti sensory cs – are EPITHELIUM). Modified dendrite forms dilation, named olfactory vesicle. 6-8 olfactory cilia extend from olfactory vesicle. Funct.: Olfactory cilia of ORC provide perception of odors. During this ORC generates nerve impulse and conducts it along basal axon into brain. Basal cs- is origin for regeneration of ORCs.
Составитель – доцент В.В. Бондаренко.
 
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