Oral histology LO4 part 2

Tissue

Cells with similar characteristics of form and function are grouped together to form a:

Organs

A tissue that is collections of similarly specialized cells that will then form into:

Epithelium, connective tissue (CT), muscle, and nerve tissue.

What are the 4 basic histological tissue types?

Epithelium

There are 2 major types of this basic tissue, these are simple: squamous, cuboidal, pseudo-stratified and columnar and Stratified: squamous (keratinized and non keratinized), cuboidal, columnar, and transitional.

Connective tissue

There are 4 major types of this basic tissue.

Solid soft: connective tissue proper, specialized (adipose, fibrous, elastic, and reticular).

Solid firm: cartilage.

Solid rigid: bone.

Fluid: blood, lymph.

Muscle

There are 2 major types of this basic tissue.

Involuntary: smooth, cardiac.

Voluntary: skeletal

Nerve

There are 2 major types of this basic tissue.

Afferent: sensory

Efferent: motor.

Ectoderm, mesodermal , endoderm

During prenatal development, embryonic cell layers differentiate into these 3 basic embryological tissue types:

Epiblast layer

What is the origin of the ectoderm?

Migrating cells from the epiblast layer

What is the origin of the mesoderm?

Hypoblast layer

What is the origin of the endoderm layer?

migrating neuroectoderm

Where do the neural crest cells originate from?``

Turnover time

The time it takes for the newly divided cells to be completely replaced throughout the tissue. This differs for each of the basic tissue types, as well as for specific regions of the oral cavity.

Epithelium

This is the tissue type that covers and lines both external and internal body surfaces, including vessels and small cavities. This is the protective covering or lining. Tissue absorption, secretion, sensory, and specialized functions. This types of tissue generally consists of closely grouped polyhedral cells surrounded by very little or no intercellular substance or tissue fluid.

Mitosis

Epithelium is highly regenerative: deeper germinal cells are capable of reproduction by this process:

Desmosomes

Epithelial cells are tightly joined by intercellular junctions of the same cell/tissue type, except in the more superficial layers. These types of intercellular junctions are called:

Hemidesmosomes

The epithelial cells are also tightly joined in to near by noncellular surfaces by this type of junction. This is when the cells/tissues are joined to a different type of cell/tissue.

Basement membrane

This membrane is located between most epithelium and deeper connective tissue, such as skin and oral mucosa, and is produced by both the epithelium and the adjoining connective tissue.

Avascular

Epithelium is ———————, having no blood supply of its own.

Diffusion

For epithelium, Cellular nutrition consisting of oxygen and metabolites is obtained by diffusion from the adjoining connective tissue, which is usually highly vascularized, providing its own source of nutrition.

Simple

This type of epithelium has the cells arranged in only 1 layer.

Stratified

This type of epithelium has the cells arranged in 2 or more layers.

Simple squamous epithelium

This type of epithelium consists of 1 layer of flattened plate like epithelial cells. Lining blood and lymphatic vessels, heart, and serous cavities as well as interfaces in the lungs and kidneys.

Simple cuboidal epithelium

This type of epithelium consists of 1 layer of cube-shaped cells that line the ducts of various glands, such as certain ducts of the salivary glands.

Simple columnar epithelium

This type of epithelium consists of 1 layer of rectangular or tall cells, such as in the lining of other salivary gland ducts, as well as the inner enamel epithelium, whose cells become enamel forming ameloblasts.

Pseudostratified columnar epithelium

Epithelium can also be classified as this type which looks stratified but isn't. This type lines the upper respiratory tract, including the nasal cavity and paranasal sinuses.

Stratified epithelium

This type of epithelium consists of 2 or more layers of cells, which only the deepest level is lining up to contact the basement membrane.

Rete pegs

Interdigitization of the outer epithelium with the deeper connective tissue, having a basement membrane between them, appears on 2D microscope section as these. This is what makes epithelium stippled.

Keratin

————— is a tough, fibrous, opaque, waterproof protein that is impervious to pathogenic invasion and resistant to friction. ————— is produced during the maturation of the keratinocyte epithelial cells as they migrate from near the basement membrane to the surface of the keratinized tissue, which occurs in certain regions of the oral mucosa found in the oral cavity.

Higher (takes longer)

The epithelium of the oral mucosa generally has a ————— turnover time than the epidermis of the skin.

Somites

Connective tissue is derived from these cells during prenatal development. Connective tissue has many functions; it is involved in support, attachment, packing, insulation, storage, transport, repair, and defence.

Somites

Differentiated mesoderm gives rise to these cells that will give rise to muscle tissue. ————— are located on the sides of the developing central nervous system.

Connective tissue

Compared with epithelium, this kind of tissue is usually composed of fewer cells spaced farther apart and containing larger amounts of matrix. Most of this type of tissue is renewable: capable of mitosis. Most cells can produce their own matrix of intercellular substance and fibres.

Matrix

Intercellular substance,Fibres.

Cartilage

All connective tissue is vascularized except for:

Fibroblasts

The most common cell in all types of connective tissue is the ———————. ——————— synthesize protein fibres and intercellular substance needed to sustain the connective tissue.

White blood cells (WBC)

Other cells found in CT include migrated ———- such as monocytes (macrophages), basophils (mast cells), lymphocytes (including plasma cells), and neutrophils.

Collagen fibres

——————— ————— are composed of the protein ———————, great tensile strength. ——————— ————— are the main connective tissue fibre type found in the body.

Fibrils

All collagen fibres are composed of smaller subunits called:

Microfibrils

All fibrils are composed of even smaller subunits called:

Cartilage and epithelial cells

What 2 tissue types have no blood vessels?

Type 1

This type of collagen protein is found in the dermis, lamina propria, bone, and tendons ( CT). Cells that produce this type of collagen are fibroblasts, odontoblasts, and osteoblasts.

Elastic fibres

————— fibres: composed of microfilaments embedded in the protein elastin, which makes it a very elastic type of tissue. This tissue has the ability to stretch and then return to its original shape after contraction or extension. Certain regions in the oral cavity such as the soft palate, contain ————— fibres in the lamina propria to allow this type of tissue movement.

Connective tissue proper

This is found deep to the epithelium and basement membrane, in the deeper layers of the skin and oral mucosa.

Connective tissue papillae

fingerlike extensions of the connective tissue that extend up into the epithelium. Interdigitations of loose connective tissue with the epithelium.

Granulation tissue

Following injury to the skin, after a clot forms and an inflammatory response is triggered with WBCs, fibroblasts migrate to produce immature connective tissue deep to the clot and newly forming epithelial surface. This immature connective tissue is considered ———————— tissue and has few fibres and an increased number of blood vessels. ———————— tissue appears as a redder, soft tissue that bleeds easily.

20

By age —— the skin begins to deteriorate, and by the age of 50 the skin is in a rapid state of degrading.