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Ear

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Slide 1: Neuroepithelial areas (where hair cells and nerve endings are found) within the membranous labyrinth.  

Slide 2: Low power image of the middle and inner ear of a rodent. To the upper left corner of the field is the tympanic membrane with the malleus (hammer) attached (in the middle ear cavity). Note the cochlea and the crista ampullaris in a semicircular canal just below the cochlea. The large structure to the right side is CNS. Compare this image to the drawing on page EE-6 of syllabus.  

Slide 3: Crista ampullaris. The membranous labyrinth is some what collapsed and the cupula poorly preserved. Note the bundle of nerve cell processes penetrating the bone.  

Slide 4: Crista, higher power of the previous slide.  

Slide 5: Macula. The membranous labyrinth is somewhat collapsed. Note the part of the vestibular nerve within the bone.  

Slide 6: Macula, higher magnification of the previous slide.  

Slide 7: Cochlea. How many sections of the organ of Corti do you see? (Ans: 3+)  

Slide 8: Organ of Corti. Locate the inner and outer hair cells, pillar cells, basilar membrane, tectorial membrane, stria vascularis, scala media (cochlear duct), scala tympani, scala vestibuli and Reissner's membrane.  

Slide 9: Scala media (cochlear duct) with the organ of Corti and stria vascularis, etc.  

Slide 10: Cochlea. Note: modiolus, spiral ganglion, cochlear nerve, organ of Corti, vestibular and basilar membranes and bony labyrinth.  

Slide 11: Organ of Corti, LM. Inner and outer hair cells, inner and outer supporting (phalangeal) cells, pillar cells, tectorial membrane -- nerve fibers coming from osseous spiral lamina supplying inner hair cell seen crossing inner tunnel to supply outer hair cells.  

Slide 12: Parasaggital LM section: poor preservation of lens, apparent lack of zonules (artifact), and retina1 detachment are due to a problem of penetration of the fixative. Note: the attachment of extraocular muscle to sclera, the dura, area cribrosa, subarachnoid space.  

Slide 13: Cornea. Identify layers.  

Slide 14: Same as 34 but LM section.  

Slide 15: Ciliary body, ciliary processes, lens, iris, trabecular meshwork, bulbar and palpebral conjunctiva, a few zonules. Monkey eye.  

Slide 16: x.s. of the "wall" of the eye from the sclera to the retina. Note the blood supplies: the "choriocapillaris" and the retinal vessels from the ciliary artery. Also locate the pigment epithelium and pigment cells in the choroid.  

Slide 17: Retina at fovea: note the lateral displacement of all layers except the photoreceptors; greater concentration of cones, which increase in height. Metal Impregnation.  

Slide 18: Section of the area cribrosa and exit of optic nerve. this is a blind spot where there are no photoreceptors. Remember that the optic nerve is brain tract. Retinal blood vessels are evident but the collapse of the area cribosa is an artifact.  

Slide 19: Eyelid, conjunctiva etc., cornea, iris, lens, Monkey. locate the chambers and the pathway for light.


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