1. By Fayez A. Elmabhouh Department of Biology
Animal Tissues By
Fayez A. Elmabhouh
Department of
Biology

2. Introduction Histology = study of tissues
Tissue = group of cells with similar structure and function
They are classified according to the shape of the cell, size, intracellular matrix.
Four types of human tissues:
Epithelial tissue
Connective tissue
Muscular tissue
Nervous tissue
The organ can may consists of one (heart) or combination of these tissues (stomach, skeleton, skin)

3. Four Tissue Types: 4

4. Epithelial Tissues Arise from the three germ layers.
Characterized by:
Their closely connected cells.
Having very little intracellular substance.
Resting on a basement membrane.
Arise from the three germ layers.
No blood vessels enter between its cell but nerves do
Covers body surfaces and forms glands.

5. Basement membrane

6. Embryonic Tissues – all adult tissues are derived from one of three embryonic tissues
Ectoderm = “outside skin”
gut
Mesoderm = “middle skin”
Cross section through embryo
Endoderm = “inside skin”
Animal embryo

7. Classification of Epithelium
1. Covering epithelia.
2. Glandular epithelia.

8. Covering epithelia
The primary function of this type of epithelia is protection.
Covering epithelia classified according to the arrangement of the cell into simple epithelia and stratified epithelia.

9. Simple epithelia
These tissues divided into four types according to the shape of cell and location of nucleus.
Consists of a single layer of cells that are in contact with the basement membrane.

10. 1. Simple Squamous Epithelium:
The cells are flat with smooth edges.
They appear spindle-shaped in cross section
Each cell containing a nucleus in the widest area.
Found in the lining blood vessels, covering serosa

11. Blood vessel

12. Serosa

13. Simple Squamous Epithelium
Simple Squamous Epithelium Bowman’s capsule

15. 2. Simple Cuboidal Epithelium
The cells in this epithelium are square-shaped in cross section.
Have central and round nucleus.
Lining the kidney tubules and Follicles of thyroid gland

16. Follicles of thyroid gland

18. single layer of cube shaped cells; large nuclei
Simple Cuboidal Epithelium
cells
single layer of cube shaped cells; large nuclei

19. 3. Simple Columnar Epithelium
Built of long pillar-shaped cells.
Containing an oval nucleus.
Ciliated: Bronchioles
Non Ciliated: lining the ileum

23. 4. Pseudo-stratified Epithelium
Single layer of cells which rest on a basement membrane but do not all reach to the free surface of the epithelium.
Their nuclei found at different levels giving the a false stratified appearance.
Cells that reach the surface carry cilia at their free ends.
Lining the trachea.

27. Keratinized: the epithelium is covered with keratin layer which is formed by the dead squamous cells (horny layer) Skin.
Non- keratinized: esophagus

28. Non- keratinized

30. Keratinized: Skin
Epidermis (Stratified Squamous Epithelium)
Dermis

32. Transitional- stratified
Found in the urinary tract (urinary bladder)
Rest on a non clear and non wavy basement membrane.
Its superficial cells are cuboidal in shape, and may contain 2 nuclei.
The basal cell layer is formed of high cuboidal cell.
The intermediate layer are polyhydral cells.
Empty
Full, the cell change into to squamous cell

36. Glandular Epithelium
The cells are specialized in secretion and thus form glands.
Formed from collections of Epithelial cell
Glands with ducts are termed exocrine
Glands without ducts are termed endocrine

37. Exocrine Glands Unicellular: formed of single cell
present in the respiratory tract and intestinal tract

39. Multicellular gland
Made of many cells and each consist of a secretary portion and duct.
They are either tubular, alveolar in form and may be simple or compound.

40. Simple tubular glands
In the digestive glands, stomach, Large intestine

41. Simple alveolar gland
Form of a flask with a round secretary portion and a narrow tubular duct.
Mucous and sebaceous gland skin

43. Compound tubular glands

44. Compound alveolar gland
Parotid gland