General Pathology Lab 1

DR. MANAR RIZIK AL-SAYYED, M.D.

6TH OCT, 2019

Cell injury

▪ Adaptation

▪ Reversible

▪ Irreversible

Adaptation

Reversible injury

Irreversible injury

Cellular adaptation to stress

1. Hypertrophy

2. Hyperplasia

3. Atrophy

4. Metaplasia

1- Hypertrophy ▪ Increase in cell size in non or limited divided organs, by:❖Hormones stimulation

❖Growth factors

❖Increase protein synthesis

▪ Can be physiological (bodybuilders, pregnancy)

▪ Or pathological (heart failure, endocrine disorders)

Skeletal muscle hypertrophy in heavy weight lifter ( physiological hypertrophy )

Microscopic view of normal skeletal muscle(Longitudinal section)

Microscopic view of normal skeletal muscle(cross section)

Pathological hypertrophy

Left ventricular hypertrophy in HTN

Hypertrophy of cardiac muscle cells

Pathological hypertrophy:Hormone stimulation

Figure 3 : Gigantism seen in young man (left) compared to normal (age- matched) young man (right) . Due to hypertrophy of body organs & tissues including bones, caused by increased growth hormone by pituitary gland before puberty .

▪ Acromegaly , photographic Showing enlargement of jaw bones and soft tissues , due to excessive production of growth hormone by pituitary gland after puberty & closure of epiphyseal plates of bones .

2- Hyperplasia

▪ Increase in cell number.

▪ Can be Physiological, caused by: ◦Hormonal : breast at puperty and during pregnancy, and uterus in

pregnancy

◦Compensatory: partial hepatectomy

▪ Or pathological:◦ Prostate

◦ Endometrium

◦ Skin wart

Gravid uterus:Adapt by both physiological hypertrophy and hyperplasia

Normal spindle smooth muscle tissue

Hypertrophied smooth muscle tissue

1000g

100g

Pathological endometrial hyperplasia

Microscopic view of normal endometrium

Endometrial hyperplasia showing numerous glands

Normal Cystic hyperplasia Hyperplasia

Prostate

Gross appearance of prostate gland showing benign prostatic glandular hyperplasia .

Microscopic view of normal prostate

Microscopic view of benign prostatic hyperplasia , showing increased number of glands

Skin wart

Microscopic view showing epidermal hyperplasia

Hyperkeratosis and acanthosis

3- Atrophy

▪ Decrease in cell size. ▪ Due to: decrease in

work load, nutrition, blood or nerve supply, or aging.

Normal Brain atrophy: narrowing of gyri and widening of sulci ,

Skeletal muscle atrophy

Atrophy of skeletal muscle fibers due to denervation (center) compared to normal skeletal muscle fibers seen at both sides of section.

4- Metaplasia ▪ Replacement of one adult cell type to another one by reprogramming of the stem cell.

▪Examples:◦Squamous

◦Columnar

◦Mesenchymal (connective tissue)

Squamous metaplasia

▪ Metaplasia of normal columnar(left) to squamous epithelium (right) in a bronchus

Microscopic view of bronchial epithelium showing squamous metaplasia of respiratory columnar epithelium

Columnar metaplasia - Barret's esophagus

Microscopic view of Barett’s mucosa showing metaplasia of esophageal

squamous epithelium into columnar epithelium

Mesenchymal metaplasia

Osseous metaplasia

Myossitis ossificans : Swelling in left femur.Mesenchymal metaplasia in skeletal muscle after injury.

Myossitis ossificans : Mesenchymal metaplasia in skeletal muscle showing cartilage & bone (left) due to injury , normal red skeletal muscle seen (right) .

Any Questions?