1. EYE and EAR Zhang Xi-Mei

2. Introduction: ª Eyes: the visual organ. § Ears: the organ of hearing and equilibrium.

3. Eye Retina Iris Vascular layer Ciliary body Walls Choroid Fibrous layer Cornea Sclera Lens Content Aqueous humor Vitreous body

4. Retina Cornea Iris Ciliary body Choroid Sclera Lens Aqueous humor Vitreous body Visual axis

5. Ⅰ. Fibrous layer Cornea: anterior 1/6 Sclera: posterior 5/6 Limbus: transition zone Function: protect inner structure & maintain eyeball shape. A. Cornea: Colorless & transparent. 5 layers Epithelium Anterior limiting membrane Stroma Posterior limiting membrane Endothelium

6. 1. Epithelium Non-keratinized stratified squamous epithelium. 2. Anterior limiting membrane (Bowman’s) An acellular homogeneous membrane. 3. Stroma Several lamella of fine collagen fibrils. 4. Posterior limiting membrane (Descement’s) Acellular homogenous membrane. 5. Endothelium Simple squamous epithelium.

7. B. Sclera: Mainly D.C.T with blood vessels and melanocytes. Sclera

8. Ⅱ.Vascular layer: L.C.T, rich in b.v. & melanocytes. A. Iris: A circular membrane with a pupil.

9. 3 layers: a. Anterior border layer: discontinuous layer of fibroblasts & melanocytes b. Stroma: L.C.T. & rich in b.v. & melanocytes. c. Epithelium: (i) anterior layer: smooth muscle (sphincter & dilator), regulate the size of pupil. (ii) posterior layer: cuboidal cells rich in melanin granules. sphincter dilator

10. B. Ciliary body: L.C.T surrounding the ciliary muscle. Triangle in cross-section. ciliary processes: anterior 1/3. ciliary zonules: from processes to lens. ciliary zonules

11. Structure: 1. ciliary muscles: smooth muscle cells. 2. ciliary stroma: L.C.T. rich in b.v. 3. ciliary epithelium: 2 layers of cuboidal cells. outer layer: highly-pigmented. inner layer: un-pigmented.

12. C. Choroid: L.C.T. rich in b.v. & pigments. Function: provide nutrients to retina.

13. Ⅲ. Retina 10 layers of histological structures 4 layers of cells: Ganglion Cells Bipollar Cells Optic Cells Pigment Cells

14. A.Pigment epithelial cells 1 layer, columnar, rich in melanin granules. B. Photoreceptor cells (optic cells) including: rod cells cone cells

15. Rod cells ： (1) photosensitive bipolar neurons. (2) a body, two opposite processes. (3) outer process: Inner segment: rich in Mt, rER, r. Outer segment: flattened membranous disks (visual purple or rhodopsin). Sensitive to low intensity light, (for night vision). Lack of Vitamin A leads night blindness. (4) inner process: the end knob synapses with the dendrite of bipolar cells.

16. Cone cells: Differ from rods in: (1). Outer segments: pyramidal disks continuous with covering cellular membrane. (2). 3 types of cones contain variety photopigments (iodopsin) on disks, sensitive to red, green, & blue light. (3). Sensitive to high intensity light & colors (day vision & color distinguishing), visual acuity is better than rods. Lack of them leads to color blindness.

17. Inner process Body Inner segment Outer segment

18. C. Bipolar cells: An axon & a dendrite, they synapse with ganglion cells & photoreceptor cells respectively. D. Ganglion cells: The dendrites synapse with bipolar cell. The axons concentrate together to form optic nerve.

19. Müller cells Neuroglia, extend entire thickness of retina; support, nourish and insulate the retinal neurons and fibers.

20. E. Optic papilla & Fovea: Optic papilla: Optic nerves pass through, & absent photoreceptor cells (blind spot).

21. Fovea: At the posterior pole of the optical axis, with very thin retina in the center, only pigment layer & cones present, high acuity of vision.

22. Ears External ear & middle ear receive transmit sound waves; Internal ear: responsible for equilibrium & hearing. Inner ear bony labyrinth membranous labyrinth

23. 1. Bony labyrinth: there are 3 portions: Osseous semicircular ducts, vestibule and cochlea. filled with perilymph.

24. 2. Membranous labyrinth: Suspends in perilymph & filled with endolymph. Consist of 4 parts (Membranous semicircular ducts, utricle, saccule, and cochlear duct).

25. 3. Cochlear duct & the organ of Corti A. Cochlear duct: Triangular shape filled with endolymph.

26. u Roof: vestibular membrane. u Outer wall: stria vascularis, rich in blood capillaries (secrete endolymph) u Floor: osseous spiral lamina & basilar membrane. The organ of Corti locates on the membrane.

27. B. The organ of Corti  Locate on the basilar membrane.  A tectorial membrane covers on the Corti.  There are auditory strings (collagenous fibrils) in basilar membrane. The length of fibrils is responsible for sound frequencies.

28. a. Supporting cells:  Pillar cells: Inner & outer. Tall columnar with wide broad base & contacted apices. A inner tunnel between them.  Phalangeal cells: At inner & outer sides of pillar cells respactively. The apex : finger-like process for supporting hair cells.

29. b. Hair cells: u Inner (1 row) & outer (3-5 rows). u On inner & outer phalangeal cells respectively. u Stereocilia touch with the tectorial membrane. u Nerve ending of cochlear N. synapses with hair cells.

30. Homework Explanation of rods, cones, optic papilla, fovea, Müller cells. Describe the structure of the organ of Corti.