Special Senses
Eye
The eye consists of the Tunica Fibrosa (Cornea and Sclera) and the Tunica Vasculosa (Iris, Ciliary Body, Choroid) and the Retina.
Cornea
Outer Corneal Epithelium
Bowmans Membrane
Stroma
Descemets Membrane
The Cornea is transparent and unvascularized. The cornea has 5 layers.
Outer Corneal Epithelium (stratified squamous epithelium)
Bowmans membrane
Stroma ( highly ordered collagen fibres, few cells)
Descemets Membrane (elastic & collagen fibres)
Endothelium (simple squamous epithelium)
Endothelium
Outer Corneal Epithelium
Bowmans Membrane
Endothelium
Descemets Membrane
Tunica Vasculosa
The Ciliary body anchors the lens via suspensory ligaments or zonule fibres. The bulk of the ciliary body is smooth muscle. The epithelium has actively transporting cells which produce the aqueous humorous and is underlain by a rich vascular supply.
There is no vasculosa under the cornea, it is composed of there layers, The vessel layer, Chriocapillary layer, Bruchs membrane (joins retina here).
The Iris (note the sphincter and dilator muscle)
Lens : covered with collagen and proteoglycan rich capsule. Simple cuboidal epithelium lies underneath capsule on anterior surface. Epithelium becomes columnar towards middle of lens and elongate into lens fibres.
Outer Nuclear Layer
Rods & Cones
Pigmented Epithelia
Outer Limiting Membrane
Outer Plexiform Layer
Inner Nuclear Layer
Inner Plexiform Layer
Ganglionic Cell layer
Layer of Optic Fibres
Inner Limiting Membrane
Choroid
Sclera
The Retina has six types of neutrons :
Photoreceptive cell
Horizontal cell
Bipolar cell
Amacrine cell
Interplexiform cells
Ganglion cells
The sclera is dense collagenous connective tissue, while the choroid consists of pigment and the choriocapillary network
Olfactory Epithelia
This is located on the roof of nasal cavity.
Basal cells
Sustentacular cells
This is a ciliated pseudo stratified epithelium with three cell types;
1) Olfactory cells : bipolar spindle shaped neurons, apical ends consists of a dilated end with 6-8 long nonmotile cilia that are draped along epithelia surface, proximal part drawn into olfactory nerve fibre
2)Sustentacular cells : with apical nuclei, also called supporting cells, tall columnar with microvilli, apical secretory granules and intercellular junction.
3) Basal cells : basal nuclei. The stem cells give rise to both olfactory and sustentacular cells
Bowmans Glands : In the lamina propria secrete "solvent" to dissolve
Gland Duct
Pacinian and Meissners Corpuscles
Meissners corpuscles are found in the papillary dermis of the integument. For light touch sensation.
Pacinian corpuscles found deep in the dermis or hypodermis of the integument, for deep touch and pressure sensations.
Taste Buds
Found on fungiform, foliate, and circumvallate papillae. Basal cells with basal nuclei give rise to more mature cells that develop taste hairs (microvilli) on their luminal surface to aid in detecting gustatory signals.