TYPES OF SKIN

- Skin & Oral Mucosa - Connective Tissue

HISTOLOGY of

For MDS

Disclaimer / Declaration

The study material included in this file and copied from relevant books / other sources are purely intended for

the welfare of our Medical /Dental students during COVID-19 Lockdown and are not for the purpose of

publication and general circulation.

aijazahmedkhan7@live.com

TYPES OF SKIN

• Thin – hairy (Hirsute)

• Thick – non-hairy (glabrous)

* ^{Thin & non-hairy}

Thickness: <1mm - to - 5 mm Weight: 8% of body mass

Size: largest organ – both in weight & surface area

Layers of Skin

• Epidermis

• Dermis

Papillary D & Reticular D

• Hypodermis

Cells of Epidermis

Keratinocytes

Non-keratinocytes -

- Merkel cells

- Langerhans cells - IEL

*

Finger prints

Stratum spinosum [ Intercellular jn. ]

Stratum granulosum

Dendritic cells in

the skin & Lymphoid tissues

Langerhans cells – Migrate as veiled cells with processed

antigen, - to paracortex – as interdigitating cells – an APC

to T-cells.

In the centre of germ. centre – as Follicular dendritic cells

present antigen to B-cell.

Experimentally-induced Papilloma of Skin

• Glands

- Eccrine (mero-) sweat gland

- Apocrine sweat & mammary glands - Sebaceous (holo-) gland

• Hairs

• Nails

Epidermal appendages

Types of hairs

• Lanugo

• Vellus

• Terminal

Shaft of hair – LM & SEM

PSU

Hair follicle L/s & Hair shaft –T/s

NAIL

Clubbing

Vitiligo - Leukoderma

Dermis:

BMZ/DEJ/RP & RR

-

- Reticular

Dermis – Dense irregular CT – Collagen - I

Leather Industry: Tannery & Gelatin

Ageing

Oral Mucosa

Oral Mucosa –Epithelium

Masticatory vs Non-masticatory

Lip:

Cheek:

Gum:

Plate:

Tongue:

Oral Mucosa

Lip & Hard Palate

Soft palate -Rbt

Dorsal & Ventral aspect of tongue

Serous & Mucous glands embedded in the tongue

Lingual papillae

[ Filiform, Fungiform, Foliate & Circumvallate ]

Taste buds & Taste pore

Taste: Chemoreception / Gustation Flavour

• Sweet

• Salt

• Sour

• Bitter

– Umami – Metallic

Posterior part of the tongue

Tonsils

• Lingual

• Faucial

• Pharyngeal

• Tubal

• Abdominal

• Peyer’s patches

Connective Tissues

&/or

Supporting tissues

Cells of CT

• Resident cells - Fibroblasts - Adipocytes

- Mesenchymal stem cells (Pluripoten)

• Migrant cells

- Macrophages - Mast cells

- Granulocytes (N E B) - Lymphocytes

• Cells of Specialized (Skeletal) CT - Chondrocytes

- Osteocytes

ECM

• Fibrillar matrix

- Collagen - Reticulin - Elastin

• Interfibrillar matrix

- Proteoglycan

- Adhesive glycoprotein - Fibronectin

- laminin - tenascin

Classification of CT

• General (

) CT

• Special (

l) CT

• Defensive (

) CT

General ( ^Ordinary ) CT

• Irregular CT

- Loose (

) CT

- Dense irregular CT

- Adipose tissue (

)

• Regular CT

• Mucoid tissue (

)

(Wharton’s jelly, Vitreous, pulp of tooth, Nucleus pulopsus of IVD)

Types of Collagen

• 29 types.

• Over 90% of the collagen in the body, however, are of type I, II, III, and IV.

• Collagen I: skin, tendon, vascular, ligature, organs, bone (main component of bone)

– Collagen II: cartilage (Hyaline cartilage), mucoid CT

• Collagen III: reticulate, commonly found alongside type I.

• Collagen IV: basement membrane

• Collagen diseases commonly arise from genetic defects that affect the biosynthesis, assembly, postranslational modification, secretion, or other processes in the normal production of collagen.

Mesenchymal Cells & Healing

Loose areolar tissue

ELASTIN RETICULIN

Adipo/-Lipocyte (Fat cells)

Multilocular

Mucoid tissue (Embryonic)

Special / Skeletal Connective

Tissues

Mesenchymal cells

CARTILAGES Hyaline

Fibro- Elastic

Chondrocyte Chondrocyte

Articular cartilage

Bones

• Cartilage vs Membrane

• Cortical (compact) vs Trabecular/cancellous (spongy)

• Woven (immature) vs Lamellar (mature)

• Osteoid (prebone) vs Osteon (HS)

• Lacunae & canaliculi

• Howship’s lacunae (resorption pit)

• Lacunae & osteocyte vs Lacunae & chondrocyte

Cells & Fibres

• Osteoblast

• Osteoclast

• Fibroblast

--- ---

• Collagen type I

Lamellae

• Circumferential

- outer circumferential - inner circumferential

• Concentric

• Interstitial

Osteoblasts & Osteoclasts

Disclaimer / Declaration

The study material included in this file and copied from relevant books / other sources are purely intended for

the welfare of our Medical /Dental students during COVID-19 Lockdown and are not for the purpose of

publication and general circulation.

aijazahmedkhan7@live.com