1. ADAPTATION OF
CELLULAR GROWTH &
DIFFERENTIATION
PRESENTED BY:
Dr. Hrudi Sundar Sahoo

2. CONTENTS:
 Introduction
 Adaptation of cells
 Mechanisms
 Adaptive disorders
Atrophy
Hypertrophy
Hyperplasia
Metaplasia
Dysplasia

3. INTRODUCTION:
 On exposure to stress, the cells make
adjustments with the changes in their
environment to:
* Physiologic needs
*Pathologic injury

4. ADAPTATION:
 PHYSIOLOGIC: Represents cells to
normal stimulation by hormones/
endogenous chemical substances.
 PATHOLOGIC: The cells have the
ability to modulate their environment.

5. SURVIVAL OF THE FITTEST:
 Adaptive responses are reversible on
withdrawal of stimulus.
 If the irritant / stimulus persists for a longer
time cell may not be able to survive.
 Thus, the concept of evolution “ survival
of fittest” holds true for adaptation as
“survival of adaptable”.

6. MECHANISM:
 Altered cell surface receptor binding.
 Alterations in signal for protein synthesis.
 Synthesis of new proteins by the target
cell such as heat-shock proteins.

7. ADAPTIVE DISORDERS OF
GROWTH:
 SIZE & NUMBER:
 Atrophy
 Hypertrophy
 Hyperplasia
 DIFFERENTIATION OF CELLS:
 Metaplasia
 Dysplasia

9. ATROPHY:
 Shrinkage in the size of the cell by loss of
cell substance.
 It represents a form of adaptive response.

10. CAUSES:
 PHYSIOLOGIC:
 Normal process of aging in some tissues,
which could be due to endocrine
stimulation & arteriosclerosis.
Eg: Atrophy of lymphoid tissue.

11. CAUSES:
 PATHOLOGIC:
 Starvation atrophy- carbohydrate/fat
 Ischemic atrophy- atrophic kidney
 Disuse atrophy- atrophy of pancrease
 Neuropathic atrophy- poliomyelitis
 Endocrine atrophy- hypopituitarism
 Pressure atrophy- erosion of spine
 Idiopathic atrophy- testicular atrophy

12. HYPERTROPHY:
 An increase in the size of the cells, which
results in enlargement of organ without
any changes in the number of cells.
 Occurs due to incresed functional demand
& hormonal stimulation.

13. CAUSES:
 PHYSIOLOGIC: Enlargement of uterus
in pregnancy.
 PATHOLOGIC: Hypertrophy of:
* cardiac muscle
*smooth muscle
* skeletal muscle
*compensatory hypertrophy

14. HYPERPLASIA:
 An increase in number of parenchymal
cells, which results in enlargement of
organ/tissue.

15. CAUSES:
 PHYSIOLOGIC:
 HORMONAL:
Eg: Hyperplasia of pregnant uterus
 COMPENSATORY:
Eg: Regeneratio of liver.

16. CAUSES:
 PATHOLOGIC:
 Occurs due to excessive stimulation of
hormones & growth factors.
Eg: Endometrial hyperplasia-following
oestrogen excess.

17. METAPLASIA:
 META-Transformation
 PLASIA-Growth
 It is a reversible change of one type of
epithelial or mesenchymal cells, usually in
response to persistant abnormal stimulus
which in turn may change into a
malignant cell.

18. CLASSIFICATION:
 EPITHELIAL METAPLASIA:
*Sqamous metaplasia
*Columnar metaplasia
 MESENCHYMAL METAPLASIA:
*Osseous metaplasia
*Cartilaginous metaplasia

19. EPITHELIAL METAPLASIA:
 The most common type.
 Metaplastic change cane either patchy or
diffuse.
 Leads to alterations in the epithelium.
 Deprivation of protective mucous secretion.
 More prone to infection.

20. TYPES:
 SQAMOUS METAPLASIA:
 Occurs due to chronic irritation
(chemical/mechanical/infective)
Eg: Bronchus in chronic smokers.
 COLUMNAR METAPLASIA:
Eg: Intestinal metaplasia in healed
chronic gastric ulcer.

22. MESENCHYMAL
METAPLASIA:
 Less often there is transformation of one
type of mesenchymal tissue to another.
 OSSEOUS: Formation of bone in fibrous
tissue, cartilage & myxoid tissue.
 Eg: In arterial wall in old people.
 CARTILAGENOUS: In healing of
fractures, where there is undue mobility.

23. DYSPLASIA:
 Disordered cellular development often
accompanied with metaplasia & hyperplasia
(ATYPICAL HYPERPLASIA).
 Occurs most often in epithelial cells, which is
characterised by cellular proliferation & cytologic
changes.

26. CAUSES:
 Occurs due to chronic irritation or
prolonged inflammation.
 On removal of simulus, the changes may
disappear.
 In majority of cases dysplasia progresses
into carcinoma insitu or invasive cancer.

27. CHANGES:
 Increased number of layers of epithelial
cells.
 Disorderly arranged cells.
 Loss of basal polarity.
 Cellular & nuclear pleomorphism.
 Increased nucleocytoplasmic ratio.
 Nuclear hyperchromatism.
 Increased mitotic activity.

28. THANK YOU