Lecture note : connective tissue summarized for viva examination

 Connective tissue

Connective tissue are composed mainly of intercellular elements with a limited number of cells

Composition of Connective tissue: Connective tissue is composed by connective tissue cells and extra-cellular matrix.

Connective tissue cells

Connective tissue cells	Functions	Figure
Permanent cells:
Fibroblasts/fibrocyte	Produce fibres of connective tissue
Macrophages	They phagocyte foreign substances, micro-organisms
Mast cells	Function in  immediate hypersensitivity reaction
Adipose cells	Energy storage, cushioning of vital organ organs
Mesenchymal stem cells

 

Wandering or transient cells:
Plasma cells	They are derived from B lymphocytes, produce antibodies
Lymphocytes: they are 3 types: T lymphocyte cells, B lymphocyte  cells & NK cells	They are involved in immune response
Monocytes	Macrophage derived from monocytes
Neutrophils	Take part in immune response
Eosinophils	Function in allergic reactions & parasitic reaction
Basophils	Take part in immune response

Extra cellular matrix: composed by connective tissue fibres and ground substanc

Connective tissue fibers: three types of fibres are present

i) Collagen fiber: formed by Collagen protein. location: bone, cartilage  

 ii) Reticular fiber: formed by Collagen protein: location : spleen, liver                

iii) Elastic fiber: formed by Elastin protein: location: vertebral ligaments, and elastic arteries.

Ground substance

·            Glycosaminoglycans (GAGs)

·         Proteoglycans

·         Multiadhesive glycoprotein

Macrophages are phagocytic cells derived from monocytes

Mononuclear phagocytotic system: cells of mononuclear phagocytotic system are derived from monocytes.

Cells of Mononuclear phagocytotic system

Name of cells	Location
Macrophage	Connective tissue, spleen
Kupffer cell	Liver
Alveolar macrophage	Lungs
Dendritic cells	Lymph node
Langerhans cells	Skin
Microglia	Central nervous system
Osteoclast	Bone

Classification of connective tissue

A. Embryonic connective tissue:

•         Mesenchymal

•         Mucous

B. Adult connective tissue:

Connective tissue proper:

Loose conne. tissue : lamina propria of GIT

Dense conne. tissue: they are two types : Regular: ex: tendon    Irregular: dermis of skin

Specialized conne. tissue:

Adipose tissue ,Elastic tissue ,Hematopoietic tissue, Blood

Supporting conne. tissue:

Cartilage, Bone

Cartilage: is a form of connective tissue composed of cells called chondrocytes and a highly specialized extracellular matrix

Types of cartilage: (according to the number of cells and the nature of the matrix) 

1. Hyaline cartilage 2.Elastic cartilage 3. Fibrocartilage

Features	Hyaline cartilage	Elastic cartilage	Fibrocartilage
Distribution	Tracheo-bronchial cartilage, costal cartilage of rib and nasal cartilage, most of the laryngeal cartilage	Epiglottis, external ear and ear canal, auditory tube, some laryngeal cartilage( corniculate, cuneiform etc.)	Intervertebral discs and pubic symphysis, articular discs of temporo-mandibular, sternoclavicular joint, menisci of the knee joint
Presence of perichondrium	Yes	Yes	No
Undergoes  calcification	Yes	No	Yes
Cell types	Chondroblast, chondrocyte	Chondroblast, chondrocyte	Chondrocytes, fibroblasts
Slide identification	*Cartilaginous matrix: is homogeneous *Cells: Lacunae (ovoid space within the matrix) contain chondrocyte *Perichondrium: present	*Cartilage matrix contain elastic fiber so it is not homogenous Lacunae contain chondrocyte *Perichondrium Present	Cartilaginous matrix: thick collagen fibres located between parallel rows of condrocytes *Cells: are arranged in  parallel rows between the bundles of  thick collagen fibers *Perichondrium: absent

 Mucous connective tissue

It is present in the umbilical cord. It consists of a specialized gelatin-like ground substance called wharton’s jelly. The spindle shaped mesenchymal cells occupies large intercellular spaces.

Topics	Loose  connective tissue:	Dense irregular connective tissue	Dense regular connective tissue
Cells	Large number of cells	Less number of cells	Less number of cells
Arrangement of cells	No definite pattern	No definite pattern	Arranged in definite pattern
Fibres	Less in amount	More in amount	More in amount
Arrangement of Fibres	No definite pattern	No definite pattern	Arranged in definite pattern
Examples:	Lamina propria of  GIT	Submucosa of GIT	Tendon