FOR CAMBRIDGE STANDARD. IT HAS ANIMAL AND PLANT TISSUES, WITH SOME ILLUSTRATED DIAGRAMS

1. Histology
CLA BOYS- 2019
King Soyekwo (Lord88)

2. OUTLINE-histology
 Introduction
 Epithelial tissues
 Connective tissues
 Muscles tissues
 Bone and cartillage
 Plant tissues
What is expected of a student here:
1. Demonstrate clear knowledge of the location,
structure and function of tissues
2. Describe precisely how the different tissues are
formed
3. Distinguish the different tissues

3. Histology
 Is the study of the organization and structure of tissues
 A tissue is a group of similar cells organized into a structural and
functional unit.
 It is a group of cells of similar structure organized for carrying out a
particular function(s).
 Tissues can be:
A. Animal tissues
B. Plant tissues

4. Characteristics of tissues
 What characteristics are common to all tissues?
 Characteristics of tissues
1. Cells of a tissues are physically linked
2. The cells of a tissue may be interspersed within intercellular
substances
3. A tissue make comprise of one or more types of cells
4. A tissue is specialized to perform a particular function

5. Diversity of tissues
 Tissues are either plant or animal tissues

6. Animal tissues
 Where do tissues originate from?
 Early in development, the cells of the growing embryo differentiate into
three fundamental embryonic tissues called germ layers.
 Ectoderm ---- outer layer of the skin and the nervous system.
 Mesoderm ----- muscles, connective tissues, skeleton, kidneys and
circulatory and reproductive organs.
 Endoderm ---lining of the respiratory tract and urinary bladder. It also
forms the glands associated with the guts and respiratory tract.

7. Diversity of animal tissues
 There are 4 major groups of animal tissues i.e
i) Epithelial tissue
ii) Connective tissue
iii) Muscular tissue
iv) Nervous tissue

8. Epithelial tissues
 Is a sheet of single or multi-layered cells covering an
external or internal surface of body organs, cavities or
ducts of animals

9. Features/ characteristics of epithelial
tissues
All epithelial tissues have the following features:
1. Cellularity—made up of tightly packed cells
2. Polarity--- apical and basal surface
3. Avascularity---
4. Supported by connective tissues
5. Regeneration
6. Germ cell origin

10. Characteristics in summary-----take note
 Epithelial tissue consists of tightly packed cells,.
 Epithelial cells are firmly held together by small amounts of a
carbohydrate based cementing
 The junctions between epithelial cells may be; anchoring junctions or gap
junctions.
 The bottom epithelial cells rests on a basement membrane, composed of
a network of collagen fibers in a matrix of lamina.
 Bottom is the basement membrane, upper surface, is the apical surface
 The apical surface may possess cilia, stereo cilia, or microvilli.
 Nerve endings may occur in the epithelium.

11. Classification of epithelial tissues
 Are classified according to number of cell layers and by
shape of individual cells;

12. Simple epithelial tissues
1. Simple squamous epithelium
Structure:
• Composed of a single
layer of flattened
cells.
• Cells have a disc
shaped nucleus at
center of each
epithelial cell
• All cells rest on a BM
Location:
• Renal corpuscles of
the kidney
• Alveoli of the lungs
• Lining of the blood
vessels-endothelium
• The ileum
• Lining of lymphatic
vessels
Function
• Diffusion of
material
• Exchange of
respiratory gases.
Adaptations:
1. One layer of cells-
reduces diffusion
distance
2. Smooth surface-
reduces friction for
flow of materials

13. 2. Simple cuboidal epithelium
Simple cuboidal epithelium
Structure
• One layer of cube shaped
cells with a spherical
centrally placed nucleus.
• Apical surface may be
pentagonal or hexagonal
• Cells contain numerous
Golgi and mitochondria
• Apical surface may have
microvilli
• All cells rest on a BM
Location
• Glands e.g thyroid glands
• Ducts e.g pancreatic and
salivary
• Tubules of the nephrons
• In the retina
• In the ovary
Adaptations
• cells have many microvilli to
increase SA
• Cells have many Golgi----
for secretion
• Cells have many mitochondria
• Relatively large cells –
protection
• Closely packed cells--
protection
Functions
• Protection
• Excretion
• Absorption
• Secretion

14. Simple epithelial tissues………
3. Simple columnar epithelium
Structure
• One layer of column shaped
cells at right angles to BM, with
an oval shaped nucleus.
• Some cells have microvilli,
forming a brush boarder.
• Often interspersed with goblet
cells.
• All cells rest on a BM
Location/distribution
• stomach where they
support other cells
• Ileum ---- for
absorption
• kidney tubules
• Lining of SG,MG,TG,GG
FUNCTIONS
1. Secretion
2. Protection
3. Absorption
4. Brush border increases the
surface area.

16. Simple epithelial tissues………
3. Simple ciliated epithelium
Structure
• One layer of column shaped
cells at right angles to BM, with
an oval shaped nucleus.
• Cells have cilia on their free
apical surface.
• Cells have columnar or cuboidal
• All cells rest on a BM
Location/distribution
• respiratory passages
• Spinal cord and ventricles
• Oviduct/fallopian tube
• Middle ear and auditory
canal
FUNCTIONS
1. Secretion
2. Protection
3. Absorption
4. Brush border increases the
surface area.

17. 5. Pseudostratified epithelium
 Found primarily in the respiratory system. Appears to be having layers
 Most cases this membrane is composed of ciliated cells with intermixed
goblet cells.

18. COMPOUND EPITHELIAL TISSUES
 Friction and other forces dictate a lining epithelium be more
durable for protection
 Stratified epithelia consist of two or more layers of epithelial cells
cemented together
 Most prevalent in the skin and portions of the digestive and
reproductive tract
 Multilayered epithelium allows deeper cells to replace the more
superficial cells as they are damaged or cast off .
 Not all cells touch the BM, but only the bottom layer.

19. Types of compound/stratified epithelia
1. Stratified squamous epithelium
• Many layers of cells placed one on
top of the other
• The surface layer has squamous
cells
• New cells formed, hence pushes
others to change their shape to
flat shape
Location:
• may remain non-keratinized as in the
oesophagus or;
• may be heavily thickened with keratin
(cornified) e.g. the skin where there is
a dead layer of cells e.g those found
lining inside the mouth and vagina.
Therefore they are for protection from
abrasion to areas exposed to wear and
tear.

20. Stratified cont…………
2. Stratified cuboidal epithelium
This epithelium has several
layers of epithelial cells, but
the surface layer of this
epithelium is composed of
cuboidal cells
Location:
• It is found in the largest ducts of sweat
glands, mammary glands, salivary
glands and in parts of the male urethra.
• Its role is protection.

21. Stratified epithelium contd…….
3. Stratified columnar epithelium:
 This epithelium has several layers of epithelial cells, but the surface
layer of this epithelium is composed of columnar cells.
 Very rare: it lines part of the urethra, large ducts of some glands,
portion of the conjunctiva of the eye.
 Its roles are protection and secretion.

22. Stratified cont……………
4. Transitional Epithelium
 Has 3 to 4 layers of cells all of similar size and shape
 Found in structures which can expand like the bladder, girdles of women
where they come back to normal after delivery, ureters and part of
urethra.
 Allows for distension of the urinary organ.
 Epithelium can change shape e.g stratified squamous epithelium if it is
stretched or stratified cuboidal epithelium if it is unstretched.
Location:
• Vagina
• Urethra
• Cervix
• oesophagus

23. Stratified cont……..
4. Glandular epithelium
 The epithelial cells are interspersed with secretory cells like goblet and
glandular cells, forming a multilayered gland.
 They are classified in different ways.

24. Classification of glandular cells
1. Based on the kind of secretion and the duct present, glands are of
two types;
a) Exocrine glands: have ducts e.g. salivary, tear intestinal and gastric
glands. Their secretions are called enzymes.
b) Endocrine glands:s: these do not possess ducts and pour their
secretions directly into the bloodstream. Their secretions are known as
hormones.

25. Classification of glandular epithelia
cont………..
2. Based on number of cells, the glands are of 2 types;
i) Unicellular: an individual epithelial cell is modified into a glandular cell as in goblet
cells.
ii) Multicellular: number of glandular cells aggregate to form a multicellular gland.
Multicellular glands can further be divided into simple or compound glands e.g. sweat
glands.

26. Classification cont…
3.Based on the shape and complexity, the exocrine glands
are of 2 main types;
 simple and
 Compound; which may further be divided as
I. Simple glands:
II. Compound glands

27. Simple and compounds continued
Simple coiled e.g.
sweat
glands
Simple tubular
e.gcrypts of
Lieuberkuhn
intestine
Simple branched
tubular e.g. gastric
glands and
Brunner’s
glands of
intestine.
Compound tubular alveolar e.g.
parts of salivary and mammary
glands.
Simple alveolar e.g.
mucous secreting
glands in frog skin..
Simple branched
alveolargland; number of
sacsopening in same duct
e.g.sebaceous glands.

28. 4. Based on the mode of secretions, the
exocrine glands are of 3 types;
 The three types are;
2. Apocrine glands :
• The apical portions of cells are
pinched off and lost during the
secretory process
• Secretory product that
contains a variety of molecular
components including those of
the membrane
1. Merocrine glands:
• Form membrane-bound
secretory vesicles internal to
the cell=salivary, pancreatic,
some sweat glands
3. Holocrine glands:
• Involves death of the cell
• The secretory cell is
released and as it breaks
apart, the contents of the
cell become the secretory
product

29. 5. Based on the form of secretion,
 Glands are of 3 types:
1. Mucous glands: secretion is in form of viscous mucous
fluid. They are called mucocytes.
2. Serous glands: secretion is clear, watery fluid containing
enzymes. They are called serocytes.
3. Mixed glands: secret both.

30. General functions of epithelial tissues
 Protection.
 Many modified to produce secretions,.
 Excretion of toxic wastes
 Absorption of materials,
 Exchange of materials and gases.
 Reception of stimuli, as in the skin and retina of the eye.
 Movement of materials.
Note:
As a student, you are required to
note the adaptation and recall the
examples where each function is
effected

31. CONNECTIVE TISSUES
 Convective tissue is a tissue composed of a ground substance
called matrix, in which other structures like cells and/or
fibres are embedded.
 Originates from embryonic mesoderm layer.

32. Functions of connective tissues
1. It binds the various tissues
2. It is a packing tissue forming sheath like bags around the body organs.
3. Areolar tissue protects the body against wounds and infections.
4. Adipose tissue stores fats, and insulates the body against heat loss.
5. Major supportive
6. Haemopoitic tissue produces blood cells .
7. Lymphatic tissue builds body immunity by producing antibodies.
8. Connective tissue separates the body organs
9. Protects blood vessels and organs where they enter or leave organs.

33. Classification of connective tissues/types

34. Can also be organized this way;;

35. Connective tissue proper
 Divide into two
1. Loose connective tissue;- adipose and areolar connective
tissue
2. Dense connective tissue;- white and yellow fibres

36. Loose connective tissue; 1 areolar connective tissue
 This is the most abundant type of connective tissue
 Found all over the body beneath the skin, connecting organs
together and filling spaces between adjacent tissues
Areolar tissue has a gelatinous
glycoprotein matrix with:
1. Protein fibres;
• Collagen fibres
• Elastic fibres
2. Different cells:
• Fat cells
• Mast cells
• Macrophages
• fibroblasts

37. Functions of areolar connective tissue
1. Binds tissues and organs together.
2. Serves as a packing tissue filling spaces between adjacent
tissues.
3. Support various tissues.
4. Provide tissues which resist strain and displacement.
5. Provides protection against wounds and infections.

38. How areolar connective tissue is adapted to its
functions
1. Has amoeboid macrophage cells for phagocytosis of pathogens.
2. Small oval shaped mast cells which secrete heparin to prevent
coagulation of blood
3. Contains adipocytes/fat cells which store fat for insulates the
body against heat lost
4. Mast cells also secrete histamine which is responsible for allergic
reactions
5. Areolar under the skin and in retina secrete melanin/ has
melanocytes. Melanin protects body against IV.
6. Collagen fibres for tensile and mechanical strength

39. Loose connective tissue: 2; adipose tissue
 Is loose connective tissues containing mostly adipocytes
 There are two types of adipose tissue;
1. White adipose tissue
2. Brown adipose tissue/yellow adipose tissue

40. 1. White adipose tissue:
 Cells appear white due to accumulation of fats.
 It is distributed throughout the body particularly the
deep layers of the skin

41. 2. Brown/yellow adipose tissue:
It differs from the white because of;
 It’s coloured and has limited location in the body e.g. it is
found around the neck.
 The fats in brown remain as small droplets i.e. do not form big
globules.
 The nucleus of the brown remains centrally placed.
This is commonly in young mammals and some hibernating
mammals. It is important in temperature regulation. It is
supplied within blood capillaries and appears red

42. FUNCTIONS OF ADIPOSE
a) Insulation against heat loss--- a bad conductor of heat
b) Provides energy—oxidized to provide heat and chemical
energy
c) Storage of vitamins----fat soluble vitamins e.g vit A, E
d) Protecting delicate organs---e.g heart, skin, etc acting as
shock absorbers

43. Reticular connective tissue
 It contains an abundance of recticular fibres.
 It provides a supporting framework for organs such as those
of the lymph nodes, spleen and the liver.

44. Dense (fibrous) connective tissue (dct)
 Has;
1. collagen/white connective tissues
2. Yellow/elastic connective tissue

45. Collagen/white connective tissue
 This consists of glycoprotein matrix containing densely packed collagen
fibres.
 Collagen tissue has fibres which are inelastic and have a high tensile
strength.
 They are found in the tendons where they attach muscles to bones.
 They are found in the Dura matter of the brain and also in the cornea of
the eye.

46. Adaptations of collagen connective tissue
1. Has unbranched fibres, making it tough to provide
support and strength
2. Numerous collagen fibres to increase tensile strength
3. Has lot of flat fibroblasts to secrete glycoprotein and
fibres
4. Has a glycoprotein where collagen fibres are suspended

47. Yellow/elastic connective tissue
 This consists of a glycoprotein matrix containing only elastic fibres.
 It is strong and elastic.
 Such tissue is found in ligaments where it binds bones to other bones.
 It is also found around the walls of arteries and it is also found as a
component of the lungs and associated air passages as well as in the
great cords of the neck.

48. Adaptations of elastic connective tissue
1) Has unbranched fibres, making it tough to provide
support and strength
2) Numerous elastic fibres to increase flexibility and
stretchability.
3) Has lot of flat fibroblasts to secrete glycoprotein and
fibres
4) Has a glycoprotein where elastic fibres are suspended

49. Reticular connective tissue
 It contains an abundance of recticular fibres.
 . It provides a supporting framework for organs
 Examples; those of the lymph nodes, spleen and the liver.

50. Specialized connective tissues
1. Skeletal tissue. Has cartilage and bone
Cartilage
 The matrix of cartilage is made up of chondrin and secreted by cells called
chondroblasts.
 Has collagen fibres.
 Some chondroblasts are embedded in spaces called the lacunae
 These cells embedded in lacunae are hence called chondrocytes.
 The margins of cartilage is covered by a protective layer called
pericondrium

51. Question

52. Types of cartilage; 1; hyaline cartilage
 Simplest form of cartilage
 It is glassy and shiny
 It is semi transparent
 Has chondroblasts embedded in chondrin
 It is elastic and compressible
 Found in the trachea

53. 2. Yellow elastic cartilage
It has a semi opaque matrix containing a
network of yellow elastic fibres.
The fibres confer greater elasticity than
found in the hyaline cartilage.
Due to high elasticity and flexibility, the
tissue quickly returns to its shape after
distortion.
It is located in the external ear, in the
epiglottis and cartilages of the pharynx

54. 3. White fibrous cartilage
 In addition to chondrocytes in the matrix, there are large bundles of
densely packed collagen fibres.
 This gives the tissue a greater tensile strength than hyaline cartilage as
well as a small degree of flexibility.
 It is located in the discs between adjacent vertebrae
 Provide a cushioning effect and the ligamentous capsules surrounding
the joints.

56. Histology advanced level 2019 cornerstone leadership academy- boys ////king soyekwo (LordSoye88?/)
The bone has an organic matrix
containing collagen fibres,
Fibres are impregnated with
small needle shaped crystals of
calcium phosphate in form of
hydroxyapatite which is brittle
but rigid giving bone great
strength.
Calcium carbonate is also
contained within the matrix

57. )
Classified in different ways:
1. Based on structure;
two different types are
are:
a) Short bones
b) Irregular
c) Long bones
1. Based on hardness; two types are
a) Spongy bones
b) Compact bones; They are mainly part of long bones
and form the long shape of the bone between two
swollen ends.

58. Histology )
Consists of an organic matrix which is muco-polysaccharide
impregnated with calcium salts mainly calcium phosphate
Matrix secreted by satellite cells called osteoblasts.
These cells are arranged in concentric rings in spaces called
lacunae.
Rings surround a Harvassian canal forming a cylinder called
Harvassian system (osteon) such that one bone contains
many Harvassian systems.
Osteoblasts secrete the bone matrix and deposite it in layers
called called lamellae around the Harvassian canal.

59. Each harvassian canal contaisn an artery and a vein
The lacunae are connected to each other by fine channels
called canaliculi which have capillaries for exchange of
materials between the osteoblasts.
The canaliculi are living part of bone carrying blood and
nutrients in the cytoplasm.

61. This is the process by which cartilage change to bone. It is also referred to as
endochondrial ossification.
It begins with rapid cell division and the cells arrange themselves in parallel column
in the longitudinal axis of bone to be formed.
A primary ossification center is then established in the middle/center.
Chondroblasts arrange in rows, become hypertrophied and let down calcium salts in
the matrix.
The process starts from the centre and works its way outwards.
Another region of ossification occurs in the shaft where osteoblasts let down fibres
on the surface of cartilage.
The region then becomes calcified gradually forming compact bones.
Osteoblasts then erode through the bone forming channels of blood vessels and
nerves.
Osteoblasts deposit bone salts in the spaces created and let down a matrix in layers.
Osteoblasts are then enclosed in lacunae interconnected by canaliculi.

62. Overview of contamination monitoring methods and Instrumentation by Raymond Agalga ( SNAS – Legon)

63. Begins from embryonic connective tissue. The dermal bones or
membraneous bones are formed in this way.
Dermal tissue in the region of bone formation becomes vascularized
and mature.
Collagen fibres are then laid down the tissue.
Calciums salts are then deposited around the fibres, thereby
establishing an ossification centre.
Erosion of calcified matrix by osteoclasts begins leading to formation
of a spongy membranous bone.
The periosteum differentiates into tough sheet of white fibrous
connecting tissue e.g bones of the skull like the cranium and clavicle
(short bones)

65. THREE TYPES:
: Voluntary muscle/skeletal/striated
Involuntary muscle/smooth/unstriated and
Cardiac muscle/myogenic/heart.

66. All muscle fibres are made up of elongated and thin cells
called muscle cells or muscle fibres.
The muscle fibres contain a specialized cytoplasm called
sarcoplasm that contains a network of membranes called
sarcoplasmic reticulum.
Muscle fibres may be bound by a cell membrane called
sarcolemma.
Each muscle may contain numerous thin myofibrils.

67. Distribution of skeletal muscles
Attached to skeleton in the head, trunk and limbs hence the
name skeletal muscle
Gross structure of a skeletal muscle
Skeletal muscle is composed of bundles of muscle fibres each
surrounded by a connective tissue,endomysium.
Each bundle of muscle fibres is surrounded by perimysium, a
connective tissue,
The various bundles are surrounded by an epimysium, a
connective tissue sheath.

68. Overview of contamination monitoring methods and Instrumentation by Raymond Agalga ( SNAS – Legon)

69. Overview of contamination monitoring methods and Instrumentation by Raymond Agalga ( SNAS – Legon)

70. MAKE SURE THAT YOU DESCRIBE THE MUSCLE AND RELATED THE STRUCTURE TO FUNCTIONS)

71. Overview of contamination monitoring methods and Instrumentation by Raymond Agalga ( SNAS – Legon)
 It consists of densely packed and elongated
fibres running parallel to each other and bound by
connective tissue.
 Each muscle fibre is a single cell containing one
nucleus.
 There are numerous fine contractile fibrils.
 The fibrils are made up of thin actin filaments
and thick myosin filaments.
 There are no cross striations in the muscle
fibres.
 Each muscle fibre is served by its own nerve
cell.
 These muscles contract rhythmically and do not
fatigue easily.
 Their actin is controlled by the autonomic
nervous system.
 They are found in the alimentary canal, walls of
blood vessels and tubes of urino-genital system.

72. HAIL KING SOYEKWO (LORD BLESS HIS LIFE)

73. Overview of contamination monitoring methods and Instrumentation by Raymond Agalga ( SNAS – Legon)