histology educational PowerPoint for students studying medicine

Types of cells seen under a microscope and meanings

1. HISTOLOGY
THE STUDY OF
TISSUES

2. TISSUES
➢A tissue is a
functional collection of
cells and associated
intercellular material
that is specialized to
carry out a specific
role.

3. Technique of Tissue
Sectioning
1. Tissue is preserved in a fixative (chemical)
2. Cut into very thin slices by a special
machine
- slices are called histological sections
3. Sections are mounted on microscope slides
4. Sections on slides are stained
-helps make cells and other structures
easier to distinguish under the microscope

7. Classification of the FOUR basic
tissues
➢1- Epithelial
➢2- Connective (CT)
➢3- Muscular
➢4- Nervous

8. Connective vs Epithelial
➢Lots of extra-cellular
material, few cells
➢Lots of blood vessels
➢Covered by other
tissues
➢Little extra cellular
material, lots of cells
➢No blood vessels
➢Usually form surface
layers and are NOT
covered by another
tissue (*except blood
vessels)
Epithelial tissue
Connective tissue

9. Epithelial Tissues
➢Flat sheet of cells with upper surface exposed to
environment or internal space. (Barriers!
Protection!)
➢Covers body surface & lines body cavities
➢Forms external & internal lining of organs
➢Constitutes most gland tissues (Secretion!)
➢Little extra cellular material
➢No room for blood vessels (avascular) so
depends on blood vessels in CT for food and
waste movement

10. Epithelial Tissue Specifics
➢Basement membrane:
⚫Anchors epith to CT
⚫Made of proteins,
acellular
⚫Basal surface - epith
surface that sits on
basement membrane
⚫Apical surface - epith
surface that faces away
from basement. “Free
Surface”
Apical Surface- faces surface, may have
cilia, microtubules
Basal
Surface-
Adheres to
Basement
membrane
Connect cells
to basement
membrane
A thickening of the basement
membrane is a contributing cause
of blindness and kidney in diabetes.

11. Basement Membrane

12. Classification of Epithelial Tissues
➢Arrangement of Cells
⚫Simple (single layer)
⚫Stratified (multiple layers)
⚫Pseudostratified (single
layer, but looks multilayered
➢Shape of Cells
⚫Squamous
⚫Cuboidal
⚫Columnar

13. Simple Squamous (“fried eggs”)
➢Flat & thin, form linings
➢Location:
⚫Mesothelium
⚫Endothelium
⚫Bronchioles and alveoli
of lungs, kidney,
tympanic membrane
➢Function:
⚫Filtration
⚫Diffusion
⚫Secretion

14. Mesothelium is the simple squamous
epithelium lining body cavities.

15. Endothelium is the simple squamous
epithelium lining blood vessels
Two blood vessels seen in cross section

16. 13. Identify the tissue.
14. Identify the structure.
15. What tissue makes up
this (#14) structure?
16. Identify the cellular
structure.
Quick Review
Click for Answers
13. Simple Cuboidal Epithelium
14. Blood Vessel
15. Simple Squamous epithelium
16. Nucleus

17. Stratified Squamous Epithelial
➢Characteristics:
⚫Many layers becoming
flatter from basal to
apical surfaces
⚫Basal cells are mitotic
⚫Apical cells are dead
➢LOCATIONS:
⚫Keritanized
•skin
⚫Nonkeritanized
•Mouth, esophagus,
pharynx, vagina
➢FUNCTION:
⚫protection

Stratified layers
of epithelial cells
Apical cells will be sloughed off and
replaced by cells in layer below.
Basal cells
Mitotic area
Cells are rounder
Stratified layers

19. Simple Cuboidal Epithelium
➢Characteristics: single layer, square or
roundish
➢Location: Ducts of many glands, lines
kidney tubules, surface of ovary
➢Function: secretion and absorption

20. Simple cuboidal epithelium lining a
tubule (longitudinal cut).

21. Simple Columnar Epithelium
➢Characteristics: tall, narrow cells
•May contain brush borders (microvilli) & goblet
cells
➢Location: lines the gastrointestinal tract from stomach to
anus, ducts of glands, gallbladder
➢Function: secretion and absorption
Nucleus

22. Simple columnar epithelium with very
regular line-up of nuclei.

23. Pseudostratified Ciliated Columnar
Epithelium
➢Location: Respiratory tract
➢Function: secrete mucous to trap foreign particles
➢Not all cells reach apical layer BUT all cells are connected
to basement membrane!
➢Cilia (sweep), Goblet cell (secrete mucous)
Cilia

24. Goblet Cell
Microvilli
Basement Membrane