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Cell Types
Roberto J. Alfabeto,  MD, FACS, FPCS,  FPSGS



Different cell types
• • • •

Epithelial tissues Connective tissues Muscle tissues Nervous tissues



Epithelial Tissue
Surface epithelium  Glandular epithelium



Surface Epithelium
 

covers or lines all body surfaces, cavities and tubes. form continuous sheet with cells bounded togetherwith cell junctions and are supported by a basement membrane. Basement membrane is never penetrated by blood vessels. cells are polarized into basal surface and apical surface.



Surface epithelium Functions
    

Selective diffusion Absorption Secretion Physical protection Containment



Classification of Surface  epithelium

Number of cell layer
Simple Stratified

Shape of the component cell
Squamous  Cuboidal  Columnar

Presence of surface specialization

Cilia  Keratin


Surface epithelia

Simple- surface epithelia consisting of a single layer of cells

Almost always found at interfaces involved in selective diffusion, absorption, and or secretion. Not for protection against mechanical abrasionRange of shape depending on their function
1 Simple squamous epithelium (a) Diagram (b) H [amp ] E ×800


Surface epithelia

Cuboidal eithelium


Columnar epithelium


Surface epithelia

Pseudostratified columnar ciliated epithelium- shows an erroneous impression that there is more than one layer of cells. Differs from a stratified epithelium by (1)exhibit polarity with nuclei mainly confined to the basal 2/3 of the epithelium (2) cilia are never present on true stratified epithelium. Almost exclusively confined to the respiratory tracts



Stratified squamous epithelium



Squamous cell carcinoma



Surface specialization

Cilia- are motile structures that project from the apical surfaces of certainepithelial cells, notably in the respiratory and female reproductive tracts





Glandular epithelium

Classification of glands:

Exocrine glands- releases their contents onto an epithelial surface either directly or via a duct. Endocrine glands- have no duct system but releases their secretion via blood stream thus is able to act on distal tissues.



Majorclassification of exocrine glands according to its major characteristics

Morphology of the gland

Secretory component
• Tubular • Acinar • Coiled • Branched

• Compound gland- branched • Simple gland- unbranched



Simple tubular glands



Compound branched tubular



Major classification of exocrine glands according to its majorcharacteristics

Means of secretion

Merocrine (eccrine) secretion- involves exocytosis and most common Apocrine secretion- dischrage free, unbroken, membranebound vesicles containing secretory product. Applies to lipid secretion like the breast and some sweat glands Holocrine secretion- discharges whole secretory cell with later disintegration of the cells with release of products. E.g.Sebaceous glands


Endocrine glands

releases secretions directly to the bloodstream rather than via a duct source of chemical messengers (hormones) that act at a distant site from the source E.g. insulin from pancreas to muscles and adipose tissues many are solid organs but some consists of widely distributed single cells

Endocrine glands
   

mostendocrine glands consists of more than one hormone product several endocrine glands consists of more than one type of secretory cells pancreas is both an endocrine and an exocrine glands in general secretion of hormones by endocrine glands is controlled by metabolic factors (e.g. blood glucose levels), the secretion of other hormones (e.g. TSH controls secretion of thyroxine) and the nervous...