Cell growth, repair and differentiation: regeneration, hyperplasia, hypertrophy, atrophy, metaplasia

1.

ZAPORIZHZHIAN STATE MEDICAL UNIVERSITY
The department of pathological anatomy and forensic
medicine with basis of law
CELL GROWTH,
REPAIR AND DIFFERENTIATION:
Regeneration, Hyperplasia,
Hypertrophy, Atrophy, Metaplasia
Lecture on pathological anatomy for the 3-rd
year students

2. INJURY

CELL DEATH
TISSUE DESTRUCTION
If the organism
is still alive
HEALING
REGENERATION
REPAIRING

3.

There are two main process of healing:
Regeneration – it is healing by
proliferation of parenchymal cells,
results in complete restoration of the
original tissues
Repairing - it is healing by
proliferation of connective tissue
elements resulting in fibrosis and
scarring

4. Types of regeneration

Physiological
regeneration
it
is
permanent renewal of cells, tissue
and organs.
Reparative
regeneration (restoration)
it is renewal of the damaged tissue by
the analogical structures.
Restructive
(pathologic) regeneration it
is renewal of the damaged tissue by the
analogical or by other tissues.

5.

PHYSIOLOGICAL REGENERATION
It is the process of replacement that occurs due to
physiologic necrosis (erythrocytes, mucosa).
There is a complete transmission of genetic
material during the process of cell division.
Levels of regeneration:
molecular-membrane
sub-cellular
cellular
tissue-organ
It is the process of realization of the
genetic program - differentiation of new
cells and apoptosis of the old one.

6.

REPARATIVE REGENERATION
Healing is the body response to injury in an
attempt to restore normal structure and
function.
Variants of RR:
Complete (restitution) – replacement of
injured cells by cells of the same type.
Incomplete with regenerative
hypertrophy (substitution with
hypertrophy)
According to the ability to regenerate there

7. Types of cells:

1. Labile cells – ("continuous
replicators") are constantly replenishing
their neighbors which have died or been
shed, multiply throughout the life under
normal physiologic condition.
They are epithelial cells of: epidermis,
alimentary tract, respiratory tract,
urinary tract, vagina, cervix, uterine
endometrium, haemopoetic cells of bone
marrow, lymph nodules and spleen

8. Types of cells:

2. Stable cells ("discontinuous replicators") –
lose their ability to proliferate after adolescence
but return their capacity to divide under stimuli
throughout adult life. Can proliferate rapidly in
response of injury, especially when required to
replace lost neighbors. They restored by two
methods - mitosis of neighbors and intercellula
reparation.
They are parenchymal cells of: kidneys, liver,
adrenal glands, mesenchymal cells of smooth
muscles

9. Types of cells:

3. Permanent cells - ("non-replicators")
cannot undergo mitosis or be
replenished after birth, but can
regenerate at subcellular level
(intercellular reparative regeneration).
Examples: neurons of nervous system,
skeletal muscle cells, heart muscles
cells (myocardiocytes).

10.

PATHOLOGIC REGENERATION or REPAIRING
Repair – is the replacement of injured
tissue by fibrous tissue
(substitution).
Forms of disregeneration:
Hyporegeneration
Hyperregeneration
Metaplasia

11.

REPAIR BY CONNECTIVE TISSUE
The new tissue is granulation tissue ("immature
scar"), and the fibrin meshwork must undergo
organization.
If any repair by fibrous tissue occurs, there will
be a scar.
Depending on the site, scar tissue may be called:
"cicatrix",
"fibrosis", "adhesions", "gliosis", "fibroplasia"

12.

OUTCOMES OF REPARATIVE REGENERATION
1. Complete renewal (restitution) of structure and
function of the damaged organ at:
а) shallow and small damage
b) inlaid damage of endothelium without violation of
basal membrane
c) damage of epithelium
Localization:
- cornea of eyes
- epithelium of any organ
- skin
- kidney, lungs, after the inlaid damage of alveolus,
endothelium, epithelium of kidney tubes.

13.

-
-
2. Substitution – incomplete structural renewal of
the damaged organ. There is partial or complete
renewal of function of organs, only at the
ordinary physical loading. Arises up after:
deep and vast damages
heart attacks and necrosis
festering-destructive processes
fungi’s process
hematoma or hemorrhage in the serous cavity
damage of vessels, channels with destruction of their
basal membranes
inlaid necrosis of the specialized structures
deep ulcers, penetrable in the muscular layer of
hollow organ.

14.

Variants of renewal after the infarcts
and strokes:
Substitution
in heart by the
connecting tissue or gliofibrosis in
brain.
Cyst
heart.
of brain, chronic aneurism of
Renewal
of functions.

15.

Variants of substitution in other organs:
hearth sclerosis or cirrhosis of organ
2. formation of cyst
3. formation of cavity – at destruction of content
through the natural opening
4. incapsulation
5. formation of joints in serous cavities and their
partial or complete obliteration
6. ossification
7. scar obliteration > hydronephrosis,
hydrocyphalia, hydrocelle, retentsion cysts
8. cicatrisation of wounds – primary pull,
secondary pull, cicatrisation under scab,
crawling of epithelium, inflammation in wound
with subsequent its clearing
1.

16.

TISSUE-ORGAN LEVEL of DIFFERENTIATION
It is observed in the damaged organs.
Processes:
Renewal of population of cells
Reparative angiogenesis
Renewal of architectonics of stroma
Renewal of specific architectonics of
stroma

17.

COMPENSATION-ADAPTATION PROCESSES
Adaptation – this aggregate of physiological processes, that is
secures adaptation of cells and organs to the changing
conditions.
Compensation – it is “normalization” of organ defects and its
adaptation.
Morphology of accommodation:
1. Apoptosis – elimination of cells
2. Aplasia is the complete failure of an organ at the
process of developing.
3. Atresia is the complete failure of the lumen in a hollow
organ.
4. Hypoplasia is the failure of an organ to grow to normal
size.
5. Malformation: wrong shaped vessels.
6. Deformation: something used to be well-formed, but it
shape was permanently altered.

18.

7. Atrophy: Shrinkage in the size of the cell by
loss of cell substance, without the cell death. If
many cells become smaller, the organ itself
becomes smaller.

19.

8.Hypertrophy: Increase in the sizes of cells, and
hence the size of the organ.
9.Hyperplasia: An increase in the number of cells
in a tissue or organ. This may be physiologic, or
pathologic.
Examples: The female breast at puberty -- under
the influence of estrogens -- and during
pregnancy and lactation (additional hormones).
The male breast in cirrhosis or estrogen therapy or
in some boys at puberty ("gynecomastia") -- all
reflect estrogens action.

20.

10.METAPLASIA: (Adaptive) substitution of one type of
fully differentiated cell by another type of differentiated
cell. A reversible change in which one adult cell type
replaced by another adult cell type.
Examples: Replacement of mucin-producing ciliated
columnar epithelium by stratified squamous epithelium
(cigaret smokers -- "to protect our delicate tissues from
the harsh effects of smoke").
11.in cancer cells.

21.

DYSPLASIA ("atypia", "atypical hyperplasia", "precancer"): This implies abnormal epithelium with
"loss of uniformity of the individual cells, as well as a
loss of their architectural orientation".
This includes "atypical hyperplasia" and "atypical
metaplasia" . “Hyperplasia" and "metaplasia" imply
the tissue cells look normal. In dysplasia, they look
distinctly abnormal, and the changes resemble
those seen