Lab (3) :connective tissue

Dr. Dalia Kamal Mohammed

Four basic types of tissue

EpitheliumConnective tissue

Connective tissue proper (examples: fat tissue, fibrous tissue of ligaments)

Cartilage Bone Blood

Muscle tissueNervous tissue

Originate from embryonic tissue called mesenchyme

Most diverse and abundant type of tissueCells separated from one another by large

amount of nonliving extracellular matrix Two components

Cells

Extracellular matrix (ECM).

o Protein fibers

o Ground substance

Cells in Connective Tissue

1. Fibroblasts2. Adipose (fat) cells3. Tissue Macrophages**4. Mast cells**

5. Lymphocytes & Plasma Cells (differentiated B-cells) **

6. “Leukocytes”**

Fixed (permanent residents)

** derived from hematopoietic stem cells and involved in immune function and inflammation

Free (transient residents)

(specifically, neutrophils, eosinophils, & basophils)

Active fibroblasts

Adipocytes predominate in adipose tissue

Single, large lipid droplet

Very active cells with many functions:• Triglyceride storage and glucose metabolism (insulin and glucagon receptors)• Secretion of many bioactive molecules:

leptin (regulates satiety) angiotensinogen (blood pressure) steroids (glucocorticoids & sex hormones)growth factors (e.g. insulin-like growth factor, tumor necrosis factor ) cytokines (e.g. interleukin-6)

Ross, M. Pawlina, W. Wheater’s Functional Histology: A Text and Atlas. Fifth Edition. 2006.

Adipocytes

Capillaries

Nucleus

Lipid (fat) droplet

Source Undetermined

Monocytes escape from blood vessels into connective

tissue where they differentiate into Macrophages

Primary function: phagocytosis and antigen presentationUniversity of Michigan Histology Collection

Plasma Cells are mature B lymphocytesthat constitutively secrete antibodies

White arrows = Golgi regionsBlack arrows indicate several plasma cells

Junqueira and Carneiro. Basic Histology. Tenth Edition. 2003. Figure 6.5.

University of Michigan Histology Collection

Fibers in Connective TissueCollagen

-Most abundant protein in human body

Reticular Fibers – Specialized type of collagen associated

with smooth muscle in organs

Elastic Fibers – Thin fibers composed of various

glycoproteins, including the protein elastin, providing elastic properties to tissues

Collagen fibers viewed by light microscopy H&E Trichrome

University of Michigan Histology Collection University of Michigan Histology Collection

Reticular Fibers

University of Michigan Histology Collection

Elastic Fibers

elastin stain (“Weigert’s”, “aldehyde fuchsin”, “Verhoeff”): elastic fibers are purple/black

Connective tissue proper Fluid connective tissue Supporting connective tissue

Connective Tissue

Dense connectivetissue

Loose connectivetissue

Lymph Cartilage BoneBlood

What are the subcategories of the three main categories of connective tissue?

Type of Connective tissue

Connective Tissues with Special Properties

• Reticular connective tissue

• Adipose connective tissue

• Elastic connective tissue

Adipose tissue

consists of :

Adipocytes; "signet ring"

appearing fat cells.

Function :

protects and insulates,

and serves as an energy

reserve

Reticular Tissue

Consists of :reticular fibers and reticular cells

Found in :

• Liver,

• spleen

• lymph nodes

composed of:

• branching elastic fibers

• network of collagen fibers

• fibroblasts Location:

• dermis,

• lungs,

• blood vessels

Elastic tissue

Thank you