91. Hyperplasia, metaplasia, dysplasia: definition of concepts, types. Macro- and microscopic changes in organs, examples of diseases.

HYPERPLASIA is an increase in the size of an organ or tissue as a result of an increase in the number of cells that make up them. Hyperplasia is observed when the mitotic activity of cells is stimulated, which leads to an increase in their number.

Physiological

- hormonal

-compensatory

Pathological

-compensatory

- vikarnaya

-hormonal (neurohumoral)

-inflammatory (hyperplasia of the spleen)

Hormonal (neurohumoral) hypertrophy and hyperplasia occur due to impaired function of the endocrine glands.The physiological prototype is hypertrophy of the uterus and mammary glands during pregnancy and lactation.

In conditions of pathology, hormonal hypertrophy occurs as a result of impaired function of the endocrine glands. An example of such hypertrophy is acromegaly caused by hyperfunction of the anterior pituitary gland with excessive production of somatotropic hormone, which usually occurs on the basis of eosinophilic adenoma. With acromegaly, there is an increase in organs and protruding parts of the skeleton. When the tumor is removed, the process is reversible.

Hypertrophic overgrowth-often found in chronic inflammation (on sliz.with images.polyps), with disorders of lymph circulation in the lowerof course. and stagnation of lymph, which leads to the proliferation of joints. fabrics (elephantiasis).Hypertrophic growth of adipose and connective tissue occurs with complete or partial atrophy of the organ (false hypertrophy).

Metaplasia is a pathological process in which one differentiated tissue is replaced by another differentiated tissue within the histione.

It is more common in the epithelium and connective tissue.The transition of one tissue to another is observed strictly within the limits of one germ leaf and develops with the proliferation of young cells.

Metaplasia is always preceded by proliferation of undifferentiated cells.

EPITHELIAL METAPLASIA

• Epidermal metaplasia (epithelial metaplasia-) the transition of the prismatic epithelium to the keratinizing flat.observed in the gut.paths with chronicinflammation, lack of vit A, in the pancreas, prostate.mammary and thyroid glands.Metaplasia begins with the multiplication of cambial cells, differentiating in the direction of the multilayer squamous epithelium.The transition of a multilayer flat non-corneating epithelium into a cylindrical one. It's called prosoplasia.

• Intestinal metaplasia-metaplasia of the epithelium of the stomach into the intestinal

• Gastric metaplasia-metaplasia of the intestinal epithelium into the gastric epithelium

METAPLASIA OF THE CONNECTIVE TISSUE

with the formation of cartilage and bone, it occurs in scars, the wall of the aorta (with atherosclerosis), in the stroma of the muscles, the capsule of healed foci of primary tuberculosis, in the stroma of tumors.This is preceded by the proliferation of young connective cells.tissues differentiating into chondro- and osteoblasts.

MYELOID METAPLASIA of the spleen, lymph nodes, the occurrence of foci of extracostomosebral hematopoiesis.

Dysplasia is a pronounced violation of the proliferation and differentiation of the epithelium with the development of cellular atypia and a violation of histoarchytictonics.

Cellular atypia is represented by various cell sizes and shapes, an increase in the size of nuclei, hyperchromia, and the appearance of atypical mitoses.

Violation of histoarchytictonics is a loss of epithelial polarity, but the basement membrane is not broken.

3 stages of dysplasia in accordance with the degree of proliferation and severity of cl. and tissue atypia

1)light(small) } reversible

2)moderate(medium) }

3) severe (significant)-precancerous

Dysplasia occurs mainly in inflammatory and regenerative processes, reflecting a violation of cell proliferation and differentiation. Its initial stages (I-II) are difficult to distinguish from pa-

tological regeneration, especially considering that dysplasia and metaplastic epithelium may occur. These stages of dysplasia are most often reversible. Changes in severe dysplasia (stage III) are much less likely to reverse development and are considered precancerous - precancerous. Sometimes they are difficult to distinguish from carcinoma in situ ("cancer in situ").

The term dysplasia is used in relation to a wide variety of diseases, which are based on an abnormality in the development of a tissue, cell or organ:

• Hip dysplasia,

• Connective tissue dysplasia,

• Fibrous dysplasia,

• Metaepiphyseal dysplasia,

• Cervical dysplasia.

The term "dysplastic" is applied to any pathological process, the etiology of which is dysplasia:

• Dysplastic coxarthrosis,

• Dysplastic status,

• Dysplastic scoliosis