Histology department medical faculty padjadjaran university
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THE EYE-VISION (The Photoreceptor System). Histology Department Medical Faculty Padjadjaran University. V.A . . A.P. Cornea. Posterior chamber. Conjunctiva. Limbus. Chamber iris. Anterior. Canal of Schelemn. Ciliary muscle. Lens. Zonula ciliaris. Med. rectus. Lat. rectus.

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Histology Department Medical Faculty Padjadjaran University

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Histology department medical faculty padjadjaran university

THE EYE-VISION

(The Photoreceptor System)

Histology Department

Medical Faculty

Padjadjaran University


Histology department medical faculty padjadjaran university

V.A.

A.P.

Cornea

Posterior chamber

Conjunctiva

Limbus

Chamber iris

Anterior

Canal of Schelemn

Ciliary muscle

Lens

Zonula ciliaris

Med. rectus

Lat. rectus

Ora serrata

Ciliary body

Vitreous

Lamina cribrosa

Sclera

Choroid

Fovea

Retina

Dura

Optic nerve

P.P.

Schematic horizontal meridional section of right eye


Histology department medical faculty padjadjaran university

T.Fibrosa (External Layer)

Sclera

Cornea

Layers

Choroid

T.Vasculosa (Middle Layer)

Ciliary Body

Iris

Eyeball

T. Nervosa (inner Layer)

Retina

ORGAN OF VISION

Lens

Fills

Anterior Chamber

Posterior Chamber

Vitreous Body

Accessory Structure (Adnexa)

Eye Lids

Tears Gland

Muscles


Histology department medical faculty padjadjaran university

TUNICA FIBROSA

  • SCLERA

  • Opaque

  • White

  • Posterior five sixth of the external layer

  • Consists of:

    • Flat Collagen Bundles

    • Ground Substance

    • Fibroblasts

  • Episclera, Tenon’s Space, Tenon’s capsule

  • Suprachoroidal lamina


Histology department medical faculty padjadjaran university

  • CORNEA

  • Transparent

  • Colorless

  • Anterior one sixth of the external layer

  • Consists of 5 layers:

    • Layer of epithelium

    • Bowman’s membrane

    • Substantia Propria

    • Descement’s membrane

    • Endothelium

Avasculer structure, receives its metabolizes by:

diffusion from adjacent vessel and from fluid of the anterior chamber


Histology department medical faculty padjadjaran university

Conjunctiva

C

A

B

D

Photomicrographs of a transverse section of cornea. A : The Cornea and conjuctiva seen at low magnification. B : The posterior corneal epithelium – also called endothelium (arrows indicate Descemet’s membrane). C : Conjuntival epithelium. D : Anterior corneal epithelium. Note the smooth contour of the surface of this epithelium.


Histology department medical faculty padjadjaran university

  • Layers of epithelium:

    • Stratified squamos epithelium

    • 5-6 cells layers

    • Deepest : columnar

    • Next : polyhydral

    • Surface : flat in shape

  • Bowman’s membrane:

    • A thin layer

    • Appears homogenous

    • Structureless under the light

    • microscope


Histology department medical faculty padjadjaran university

  • Substantia propria

    • 90% of the thickness

    • Composed:

      • Collagenous fibrils arranged in lamellae (parallel with the surface)

      • Mucoid cement

      • Cells

  • Descement’s membrane:

    • Appears homogenous

    • Fibrous protein of collagen type

  • Endothelium:

    • Single layers of cells

    • Low cuboidal epithelium


Histology department medical faculty padjadjaran university

LIMBUS (Corneoscleral Junction)

  • Area of transition from transparent collagen bundles of the cornea to the white opaque fibers of the sclera

  • The corneal epithelium, as it passes over into the limbus, increases in thickness up to ten or more cells

  • The corneal stroma losses its regular lamellar arrangement

  • In the stromal layer, irregular endothelium – lined channels, the trabecular mesh work, merge to form the canal of Schlemm


Histology department medical faculty padjadjaran university

Canal of schlemm

Cornea

Limbus

Anterior chamber

Lens

Ciliary muscles

Zonule

Iris

Ora serrata

Posterior chamber

Ciliary body and process

Vitreous body

Choroid

Photosensitive retina

Sclera

Sclera

Optic papilla

Fovea

Sclera

Choroid

Pigment epithelium

Optic nerve

  • Diagram of the right eye, seen from above, showing the structure of the eye, retina, fovea and ciliary body. Arrows in the anterior chamber show the direction of flow of aqueous humor. An enlarged diagram of the fovea is shown at lower right.

  • Axons of ganglion cells

  • Bipolar cells

  • Rods

  • Cones


Histology department medical faculty padjadjaran university

TUNICA VASCULOSA

  • A. CHOROID

  • Divided into four layers:

  • The Suprachoroid, lamina suprachoroidea or epichoroid

    • Consist of lamellae, each lamella: very thin membrane

  • Vessel layer (stratum vasculosa)

    • Outer layer : large vessels

    • Inner layer: medium sized vessels


Histology department medical faculty padjadjaran university

  • 3. The capillary layer (Lamina Choriocapillaris).

  • Serves of nutrition for the outer layers of the retina

  • 4. The lamina Vitrea, lamina elastica / basalis, or

  • membrane of Bruch:

    • Non cellular membrane

    • Two layers:

      • The outer elastic lamellae, very thin

      • The inner cuticle lamellae, relatively thicker


Histology department medical faculty padjadjaran university

Section through retina, choroid and sclera.

Sc.

Ch = Choroid;

Ret = Retina;

1 = Suprachoroid;

2 = Vessel layer;

3 = choriocapillaris

4 = Lamina vitrea

5 = Pigment epithelium

6 = layer of rods and

cones

7 = external limiting

membrane

8 = outer nuclear layer

9 = outer plexiform layer

10 = inner nuclear layer

11 = inner plexiform

12 = ganglion cell layer

13 = nerve fiber layer

14 = internal limiting

membrane

1

Ch.

2

3

4

5

6

7

8

9

10

Ret.

11

12

13

14


Histology department medical faculty padjadjaran university

B. CILIARY BODY

  • Two zones:

  • The orbiculus ciliaris (Pars Plana)

    • The posterior two thirds

    • Appears darkly pigmented

    • Relatively smooth

  • The corona ciliaris (Pars Plicata)

    • The anterior third

    • Bears some 70 to 80 radially arranged ridges, the ciliary processes


Histology department medical faculty padjadjaran university

Circumlental space

Zonula fibers

Lens

Ciliary processes

Ora serrata

Orbiculus ciliaris

Ora serrata, ciliary body, zonula ciliaris and lens as viewed from behind after removal of the vitreous body


Histology department medical faculty padjadjaran university

  • IRIS

  • A thin circular diapraghma

  • A circular aperture: the pupil

  • Divides the space between the cornea and the lens into two chambers:

    • The anterior chamber

    • The posterior chamber


Histology department medical faculty padjadjaran university

V.A.

A.P.

Cornea

Posterior chamber

Conjunctiva

Limbus

Chamber iris

Anterior

Canal of schelemn

Ciliary muscle

Lens

Zonula ciliaris

Med. rectus

Lat. rectus

Ora serrata

Ciliary body

Vitreous

Lamina cribrosa

Sclera

Choroid

Fovea

Retina

Dura

Optic nerve

P.P.

Schematic horizontal meridional section of right eye


Histology department medical faculty padjadjaran university

Layer of iris is five layers:

  • Endothelium

    • A very thin delicate layer

    • Difficult to demonstrate in sections

    • Best shown after treatment with silver nitrate


Histology department medical faculty padjadjaran university

  • The anterior border layer

  • The color of the iris upon:

    • The thickness of the anterior border layer

    • And the degree of pigmentation of it cells

    • In the brown iris:

      • The layer is thick

      • The cells heavily pigmented

    • In the blue iris:

      • The layer is thin

      • The cells minimum amount of pigment


Histology department medical faculty padjadjaran university

  • The vessel’s layer (stroma)

    - Consists of a great number of blood vessel

  • M. Sphincter pupillae:

    - In the pupillary zone

    Contraction: Reduced the diameter of the pupil

    - The dilatator pupillae

    Contraction: Dilatation of the pupil

  • The pigment epithelium


Histology department medical faculty padjadjaran university

Stroma

Anterior border layer

Endothelium

Sphincter pupillae

Pigment epithelium

Horizontal section through pupillary zone of human iris


Histology department medical faculty padjadjaran university

TUNICA NERVOSA

  • Consists of two portions :

  • The posterior portion is photosensitive – pars optica retinae

  • The anterior part is not photosensitive – pars coeca retinae. Constitutes the inner lining of the ciliary body and the posterior part of the iris

The retina forms the pars optica retinae. The scalloped anterior border of the retina is known as the orra serrata.


Histology department medical faculty padjadjaran university

Sclera

Epithelium

Choroid

Photomicrograph of a section of retina in the transition (arrow) between the photosensitive (at left) and blind (at right) parts. This transition is called the ora serrata. Note the pigment epithelium, the choroid and the sclera.


Histology department medical faculty padjadjaran university

RETINA

  • The retina consists of ten layers ,

  • except at :

  • The fovea centralis

  • The optic disc (optic papillae)

  • The extreme periphery


Histology department medical faculty padjadjaran university

Canal of schlemm

Cornea

Limbus

Anterior chamber

Lens

Ciliary muscles

Zonule

Iris

Ora serrata

Posterior chamber

Ciliary body and process

Vitreous body

Choroid

Photosensitive retina

Sclera

Sclera

Optic papilla

Fovea

Sclera

Choroid

Pigment epithelium

Optic nerve

  • Diagram of the right eye, seen from above, showing the structure of the eye, retina, fovea and ciliary body. Arrows in the anterior chamber show the direction of flow of aqueous humor. An enlarged diagram of the fovea is shown at lower right.

  • Axons of ganglion cells

  • Bipolar cells

  • Rods

  • Cones


Histology department medical faculty padjadjaran university

  • Development of the retina :

    • The retina derived from an evagination of the anterior cephalic vesicle or prosencephalon

    • As this co-called optic vesicle comes into contact with the surface ectoderm, it gradually in vaginates in its central region forming a double – walled optic cup.

    • In the adult :

      • The outer wall gives rise to a thin membrane called the pigment epithelium

      • The inner layer is derived the optical or functioning part of the retina


Histology department medical faculty padjadjaran university

Diagrams of 4 stages in the development of the eye

Lens Vesicle


Histology department medical faculty padjadjaran university

Layer of the RETINA :

  • Pigment epithelium

  • Layers of rods and cones

  • External limiting membrane

  • Outer nuclear (or granular) layer

  • Outer flexiform (or molecular) layer

  • Inner nuclear (or granular) layer

  • Inner flexiform (or molecular) layer

  • Ganglion cell layer

  • Nerve fiber layer

  • Internal limiting membrane


Histology department medical faculty padjadjaran university

4. Collagenous fibers

1. Sclera

5.Chromatophores

2. Choroid

6. Blood vessel

7. Pigment epithelium

8. Rods and cones

9. Outer limiting membrane

10. Outer nuclear layer

3. Retina

11. Outer plexiform layer

12. Inner nuclear layer

13. Inner plexiform layer

14. Ganglion cell layer

15. Nerve fiber layer

16. Inner limiting membrane

RETINA, CHOROID AND SCLERA


Histology department medical faculty padjadjaran university

16. Sclera

17. Suprachoroid layer (lamina fusca)with chromatophores

1. Blood vessels of the choroid

18. Vascular layer of the choroid

2. Chromatophores

19. Choriocapillary layer

3. Pigment cells in the retina

20. Processes of pigment cells extending between rods and cones

4. Rods

21. Cones

5. Cones

22. Rod

6. Outer limiting membrane

23. Outer limiting membrane

24. Nuclei of cones

7. Nuclei of cones

25. Nuclei of rods

8. Nuclei of rods

26. Outer processes of Muller’s cells

9. Outer plexiform layer

27. Synapses between horizontal and visual cells

28. Synapses between cones and bipolar cells

10. Nuclei of bipolar, horizontal, amacrine and Muller’s cells

29. Bipolar cell

30. Muller’s cell

31. Amacrine cell

32. Synapses between processes of bipolar, amacrine and ganglionic cells

11. Inner plexiform layer

33. Ganglion cell

12. Ganglion cell layer

34. Fiber of optic nerve

13. Muller’s fibers

14. Axons of ganglion cells

35. Horizontal fiber

15. Inner limiting membrane

36. Inner limiting membrane

37. Inner fibers of Muller’s cells


Histology department medical faculty padjadjaran university

THE ROD CELLS AND THE CONE CELLS

  • The rod cells :

  • Photo pigment : Visual purple or rhodopsin

  • Each retina has about 120 million rods

  • Sensitive to light and the receptors used when low levels of light


Histology department medical faculty padjadjaran university

  • The Cone cells :

  • Photo pigment : iodopsin

  • Each retina has about 6 million cones

  • Sensitive only to light of a higher intensity

  • Maximum sensitive is in the red, green or blue of the visible spectrum


Histology department medical faculty padjadjaran university

Discs

Outer segments

Cilium

Narrow collar

Inner segments

Outer limiting membrane (Composed of terminal bars and filaments of mueller cells)

Nuclei

Synapses

Mueller cell cytoplasm

Processes of bipolar cells


Histology department medical faculty padjadjaran university

The light and the nervous impulses travel in the retina

Diagram showing the arrangement of the three layers of neurons in the retina. Observe that the light and the nervous impulses travel in opposite directions.


Histology department medical faculty padjadjaran university

LENS

  • Transparent

  • Biconvex, posterior surface has a greater convesity than the anterior surface

  • Three structural component :

    • Lens capsule : homogenous

    • Subcapsular Epithelium

      • Single layer of cuboidal epithelium cells

      • Present only on the anterior surface

    • Lens Fibers :

      • Appear as thin flattened structures

      • They are highly differentiated cells derived from cells of the subcapsuler epithelium


Histology department medical faculty padjadjaran university

The lens, viewed from behind and from the side.

From section through margin of lens longitudinal sections of lens fibers and transition from epithelium to lens fibers. a : Lens fibers; b: capsule; c : epithelium


Histology department medical faculty padjadjaran university

The lens is held in place by the zonula ciliaris (Zonula of Zinn, suspensory ligament)

  • The Zonula on :

    • The lens capsule

    • The ciliary body

The zonula is important in process accomodation


Histology department medical faculty padjadjaran university

Connective tissue

Lens

Anterior view of the ciliary processes showing the zonules attaching of the lens. Zonule fibers are bundles of microfilaments (oxytalan fibers) from the elastic fibers system. The zonules form column (A) on either side of the ciliary processes (B), which meet on a single site (C) as they attach to the lens.


Histology department medical faculty padjadjaran university

THE VITREOUS BODY

  • Transparent gell

  • Amorphous

  • Intercellular substance

  • Bounded by :

    • The internal limiting membrane of the retina

    • The lens

    • The posterior zonular membrane


Histology department medical faculty padjadjaran university

10. Superior tarsal muscle (of Muller)

1. Hair follicles

11. Adipose tissue

2. Sweat glands

12. Accessory lactrimal gland (of Krause)

3. Epidermis and dermis

13. Lymphatic tissue

4. Rudimentary hari follicle

5. Palpebral part of orbicularis oculi muscle

14. Epithelium of palpebral conjuctiva

15. Tarsal glands (Meibomian glands)

6. Connective tissue

16. Tarsus

17. Palpebral conjuctiva

7. Arteriole

8. Ciliary glands : large sweat glands (of Moll)

18. Duct of tarsal gland (Meibomian gland)

19. Ciliary muscle (of Riolan)

9. Sebaceous glands (of Zeiss)

20. Hair follicles of eyelashes

Accessory structures

A. EYELIDS


Histology department medical faculty padjadjaran university

B. Lacrimal Apparatus

  • Consists of :

    • The lacrimal gland

    • Canaliculi

    • Lacrimal sac

    • Nasolacrimal duct


Histology department medical faculty padjadjaran university

  • The Lacrimal Gland :

    • Tear secreting gland

    • Located in the anterior superior temporal portion of the orbit

    • Consist of several separate glandular lobes

    • Tubulo alveolar

    • Serous type

    • Myoepithelial cells surround the secretory portions


Histology department medical faculty padjadjaran university

6. Venule

1. Glandular alveoli

7. Interlobular duct

8. Glandular alveoli

2. Intralobular ducts

3. Myoepithelial cell (basal or basket cell)

9. Interalveolar connective tissue

10. Arteries

4. Interlobular connective tissue

5. Outpocketing of glandular cells

11. Interlobular duct

LACRIMAL GLAND


Histology department medical faculty padjadjaran university

Lacrimal Gland

Cornea, Bulbar and palpebral conjunctiva

Lacrimal Puncta

Lacrimal Canaliculi

Lacrimal Sac

Nasolacrimal Duct

Inferior meatus of nasal cavity

DRAINAGE OF TEARS


Histology department medical faculty padjadjaran university

THE LACRIMAL DRAINAGE SYSTEM


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