interstitial pathology


I- definition -General – morphological Reminder – Method of study of interstitial medium :

1- Definition :

The intercellular system represents a set of spaces or areas which form the die or mold of a tissue or organ.

2- Overview :

Being the place or perform all exchanges, intercellular system is the essential support to the life of all cells.

This system is called also – Fabric common connective – Chorion ou interstitium.

Ubiquitously seat, it is widely distributed throughout all tissues, extending between the vascular elements, basement membranes of epithelia and the membranes of specialized mesenchymal cells.

The system ensures intercellular :

  • A supporting role
  • A role of nutrition for all metabolic exchange between capillaries and cells.
  • A role of the body's defense
  • A role in cell differentiation.

3- structural and physiological reminder :

The system consists of intercellular 2 essential components :

  • The ground substance
  • The elements of nature fibrillar

→ The ground substance : This is the proper intercellular matrix wherein based cells and connective tissue fibers. It is amorphous, homogeneous and unstructured. Composed primarily of :
– neutral or mucopolysaccharides gycoprotéïnes… .antigenic role
– Mucopolysaccharides acides, simple sulfated or behaving like cementitious material substances.

→ Elements of Nature fibrillar : Play an important role in maintaining the integrity and support structures.
– Collagen fibers : Their diameter is 1 at 12 nm, consist of bundles of fibrils 20 at 200 pim. They are very extensible, highly resistant to voltage, but flexible. Consist of a protein : collagen, manufactured by the fibroblast form of procollagen and tropocollagen is crossing the plasma membrane of the fibroblast.
– The fibers reticulin : very thin (0,2-1 jim) ; branched. There appears to be an immature form of collagen fibers.
– Elastic fibers : they are of variable thickness branched (ljwm ALO / in). Subjected to tension, they stretch and return to their original length at the end of this tension. This imparts elasticity to the tissue they are (vessels, skin, lung)

4- Techniques and methods of study :

→ macroscopic Study :
– The ground substance is transparent, gelatinous and viscous.
– Fibrillar elements are whitish, consistency varies with amount, their nature and the predominance of one of their varieties (collagen, reticulin or elastic).

→ optical microscopy study : With special stains

  • The ground substance : Alcian Blue and PAS… .color mucopolysaccharides. The first in turquoise blue, the second in fuschia pink.
  • Fibrillar elements :

– HE safran : stains collagen Yellow, reticulin fibers and elastic fibers Eosinophils (hot pink)
– Masson trichrome : collagen Green or Blue
– The silver staining stained reticulin fibers in Brown Black
– The color orceïne les fiber élastiques in Brun

II – Pathology interstitial environment :

1- Factors influencing this pathology :

  • Sex hormones : estrogen, progesterone, testosterone
  • polymerizing enzymes (Cathepsine D, plastine) dépolymérisants (collagenase hyalurinodase, elastase)
  • The endocrine secretions : PTH, glucocorticoïdes ACTH
  • TRT : Antinflammatoires

2- The early alterations of the intercellular substance :

A – quantitative changes fibrillar elements :

→ Depletion elements or atrophy :

Definition : it refers to the reduction of the amount of the volume of the intercellular substances in relation to the normal state Examples :
– Decrease in bone protein matrix in osteoporosis
– Decrease or disappearance of elastic fibers of the dermis observed in stretch marks.
– Decreased lung elastic network … .pulmonary emphysema (For al antitrypsin deficiency)

→ Increase elements or hypertrophy : THE FIBROSIS OR sclerosis

1- Definition : This is an increase of intercellular fibers causing induration of an organ or tissue c & rsquo; is to say its sclerosis. Most often it interests collagen.

2- Circumstances of appearance :

  • The secondary post sclerosis or inflammatory
  • Primitive sclerosis called dystrophic

3- Main varieties sclerosis :

The collagen sclerosis : related to an overproduction of collagen fibers :
– In the last stage of inflammation
– During chronic inflammation (TBC, Syphilis)
– During autoimmune diseases : scleroderma

The elastic sclerosis and élastoses : The actinic skin damage (skin senile,Prolonged exposure to UV radiation)

4- Topography :

The sclerosis can be systematized (Ex : Primary interstitial pulmonary fibrosis) ; or mutilating and dissecans (After myocardial sclerosis) and finally encircling (Tubercular abscess and cave).

5- Consequences of multiple :

→ Functional consequences : can be
– beneficial : Multiple scarring during wound
– adverse : Multiple systematic primitive interstitial pulmonary fibrosis resulting in severe respiratory failure.

→ morphological Consequences : The sclerosis can
– F body volume increase… .multiple hypertrophic (Ex : Chronic cholecystitis hypertrophic)
– decrease in volume of the organ atrophic sclerosis (Ex : Chronic cholecystitis atrophic)
– Edit the morphological appearance of the organ : Liver cirrhosis.

B – qualitative modification of fibrillar elements :

In some cases there is an increase with qualitative change in the fibrillar component (Ex : keloid).

C – Changing the fundamental substance :

  • Metamorphism and conjunctival metaplasia : It is the transformation of a basic substance into another fundamental substance (Ex : chondrin in ossein in endochondral ossification)
  • Impregnating : Refers to the attachment in the intercellular medium normally absent substances or products in this medium . (Ex : Limestone impregnation of elastic fibers in the medical calcification or necrosis in a home).
  • Infiltrations : It refers to a penetration of the intercellular medium by a neighborhood substance, diffuse character or elements isolated (Ex : Edema, gas gangrene, infiltration of inflammatory cells or tumor).

Course of Dr N. lemma – Faculty of Constantine