1

Bio211Laboratory 2

Epithelial and Connective Tissues

2

Tissues• Tissues to be examined under the microscope

– Epithelial Tissue (p. 79 Lab Manual) [TODAY]– Connective Tissue (p. 93 Lab Manual) [TODAY]– Muscle/Nervous Tissues (p. 109/117 Lab Manual) [NEXT LAB]– Integument (p. 123 Lab Manual) [NEXT LAB]

• Refer to your– Wood’s Lab Manual for pictures of tissues/guidance– Lab Guide (handout) for a checklist of tissues/structures you are

responsible for• Objectives

– Learn to recognize each of the tissue types under the light microscope by structure, not color, and how they are constructed

– Provide at least one example of where each tissue is found in the body on lab exam

3

Tissues - Overview

• Recall that tissues are layers or masses of cells that have common functions

• The study of tissues is called…?

• Usually the cells within tissues are separated by nonliving, intercellular materials that the cells produce.

Histology

4

Sectioning and Staining of Tissues for Microscopy

Four steps in tissue preparation

- Fixation stabilizes and preserves the tissue

- Embedding converts the tissue into a solid form which can be sliced ("sectioned")

- Sectioning (slicing) provides the very thin specimens needed for microscopy (2-D)

- Staining provides visual contrast and may help identify specific tissue components.

5

Hematoxylin and Eosin (H&E) Stain

Hematoxylin – deep purple or blueEosin – red (pink) color

6

Epithelial Tissue

• Widespread throughout body

• A “covering and lining” tissue

• Always has a free surface

• Underside of tissue is anchored to a “basement

membrane” (nonliving layer)

• Lacks blood vessels

• Cells are tightly packed

7

Epithelial Tissue - Epithelial tissues are

classified by a combination of two characteristics:– Layering (or stratification)

• Simple (single layer)

• Stratified (two or more layers)

• Pseudostratified (‘false’ stratification – really one layer)

• Transitional (can change shape when stretched)

– Cell shape

• Squamous (flat)

• Cuboidal (cube-shaped)

• Columnar (elongated; rectangles)

8

Simple Squamous Epithelial Tissue

Free surface

9

Stratified Squamous Epithelium

10

Simple Cuboidal Epithelium

11

Simple Columnar Epithelium

Note ‘brush border’ on the free surface of simple columnar cells and scattered goblet (mucus-producing) cells

12

Pseudostratified Ciliated Epithelium

Appears stratified because nuclei are located at different levels

However, ALL cells reach the basement membrane

Note how different cilia look as compared to microvilli of brush border on simple columnar cells

13

Connective Tissue

• Most abundant type of tissue by weight

• Bind, support, protect, fill in spaces, and aid in repair

• Cells are farther apart than epithelium

• Have abundant intercellular matrix, consisting of fibers and ‘ground substance’

• Can usually divide

• Usually has a good blood supply

15

Loose (areolar) Connective Tissue

Collagen fibers are thick bundles

Elastic fibers are thinner, more ‘wavy’

16

Dense (Regular) Connective Tissue

Note the dense packing of collagen fibers and the fact that all the fibers run in the same direction (regular)

Note that collagen fibers are OUTSIDE of the fibroblasts

17

Adipose (fat) Tissue

Note the nuclei are pushed to one side of the cell by the fat droplets in the cell cytoplasm

18

Cartilage Overview

19

Hyaline Cartilage

‘Chondro’ = cartilage

Cartilage cell = chondrocyte

20

Fibrocartilage

Note the collagen bundles present in fibrocartilage that are NOT present in hyaline cartilage

Note also fibers are large relative to chondrocytes

21

Elastic Cartilage

Note that the elastic fibers are small and ‘wavy’ as compared to the thick collagen fibers of fibrocartilage

Note that fibers are small relative to chondrocytes

22

Bone

‘Osteo’ = bone; Bone cell = osteocyte

23

Structure of Osteons

Know the structures that make up osteons

(Note: Central canal = Haversian canal = Osteonic canal

24

Blood

Be able to distinguish among erythrocytes (RBCs), leukocytes (WBCs), and platelets

(Erythrocytes)

(Leukocytes)

25

Review

• Epithelium– Simple squamous – single layer of flattened cells– Simple cuboidal – single layer of square cells– Simple columnar – single layer of rectangular cells;

may have goblet (mucus) cells– Stratified squamous – stacked squamous cells– Pseudostratified ciliated columnar

• Look like stratified by they are not

• Have cilia

• Have goblet cells

26

Review

• Connective Tissue Proper– Loose (areolar)– Dense connective tissue– Adipose tissue

• Specialized connective tissue– Cartilage

• Hyaline (prominent lacunae)• Fibrocartilage (thick collagen fibers)• Elastic cartilage (thinner, wavy elastic fibers)

– Bone (have circular osteons)– Blood

27

What you should do in lab today…• Using the microscope and the slide boxes

– Look at the slides listed on your Laboratory Guide (handed out in first lab) for:

• Epithelial tissue• Connective tissue

• BE SURE you can recognize each of the tissue types listed in your Laboratory Guide; check off ONLY after you can recognize a tissue– KNOW at least one place in the body where each of

the tissue types is found

• Come up and get tested on slides for today (identification only – not location in body)

28

For next lab…

• For Muscle and Nervous Tissue– Read Exercise 9 & 10 in Wood’s Lab Manual– Look at the histological photos in your Lab Manual

and in your textbook

• For Integument– Read Exercise 11 in Wood’s Lab Manual– Look at histological photos in your Lab Manual and

in your textbook