Histology: Primary TissuesConnective

BIOLOGY 220General Human Anatomy

Fall 2002

Classes of CT

figure

CLASSIFICATION OF CONNECTIVE TISSUES

A. Embryonic connective tissue– Mesenchyme– Mucous connective tissue

(wharton’s jelly)B. Adult connective tissue

– Connective tissue proper : fibers; fibroblasts

Continued…

ADULT CT (continued)

1. Loose (areolar) connective tissuea. Loose (areolar) connective

tissueb. Adipose connective tissuec. Reticular connective tissue

2. Dense CTa. Irregular CT: eg: dermis of

skin fibrous capsule of jointsb. Regular CT eg: tendons, most

ligamentsc. elastic

A. CHARACTERISTICS OF CONNECTIVE TISSUES

1. Large amount of intercellular material

Intercellular matrix Extracellular material Matrix Fibers (collagenous, reticular, elastic)

2. Cells occur singly, or in small groups

3. Primarily mesodermal (through mesenchyme) fibroblast collagenous fibers

:Connective tissue cell line

TISSUES: FUNCTIONS OF CONNECTIVE TISSUES

• Bind structures together• Provide protection• Serve as supportive framework• Fill spaces• Store fat (excess food

materials )• Repair damaged tissue• Produce formed elements of

blood• Etc.

ADULT CONNECTIVE TISSUES: LOOSE (AREOLAR) C.T.

•Widely distributed in the body•Found in mucous membranes

around vessels and nerves•Forms subcutaneous layer with

adipose tissue•Fibers and cells in semi-fluid matrix

1. LOOSE (AREOLAR) C.T.

a. General:1. Location: subcutaneous tissue

(superficial fascia)2. Characteristics:

Loose Lots of space

3. Functions: NRG storage repair after injury combats infection

ADULT CONNECTIVE TISSUES: LOOSE (AREOLAR) C.T.

•Fibers “loosely” arranged

•Three types of fibers: –Collagenous–Elastic–Reticular

b. COMPONENTS OFAREOLAR (LOOSE) CONNECTIVE TISSUES: TYPES OF

FIBERS

1. Collagenous fibersCollagen: fibroblastIncreased age = strongTropocollagen collagen c. fiber (fibroblast)

CONTINUED…

b. COMPONENTS OFAREOLAR (LOOSE) CONNECTIVE TISSUES: TYPES OF FIBERS (continued)

2. Elastic fibersa. Protein subunit: elastinb. Characteristics: elastic freely

branching cylinders

Continued…

ADULT CONNECTIVE TISSUES: ELASTIC C.T.

•Fibers are predominately elastic•Fibroblasts located between fibers•Provide stretch and strength•Found in respiratory tract, large

arteries, true vocal cords

ELASTIC CONNECTIVE TISSUE

b. COMPONENTS OFAREOLAR (LOOSE) CONNECTIVE TISSUES: TYPES OF FIBERS (continued)

2. Reticular fibersa. Subunit: glycocollagenb. Characteristics: fine, branching

form “networks”

ADULT CONNECTIVE TISSUES: RETICULAR C.T.

•Fibers are reticular•Form stroma for many organs•Binds together smooth muscle fibers

RETICULAR CONNECTIVE TISSUE

c. COMPONENTS: GROUND SUBSTANCE (MATRIX, INTERSTITIAL

MATERIAL)

1. Derived from CT cells2. Can be solid gel fluid

CLASSIFICATION: EMBRYONIC CONNECTIVE TISSUES

•Mesenchyme: Source of other connective tissue in embryo–Found beneath skin and along bones

–Cells scattered throughout adult connective tissue

•Differentiate into fibroblasts

ADULT CONNECTIVE TISSUES: LOOSE (AREOLAR) C.T.

d. Numerous, varied cells1)Fibroblasts: Most common2)Macrophages (histiocytes); in

blood: monocytes3)Plasma cells (lymphoid

cells); In blood: lymphocytes4)Mast cells; in blood: basophil5)Adipose (fat cells) Adipocytes6)Leukocytes

AREOLAR CONNECTIVE TISSUE

ADULT CONNECTIVE TISSUES: ADIPOSE TISSUE

•Loose connective tissue specialized for fat storage

•Adipocytes: Derived from fibroblasts

•Functions –Padding – Insulation–Long term energy storage

ADIPOSE TISSUE

ADULT CONNECTIVE TISSUES: DENSE (COLLAGENOUS) C.T.

•Closely-packed fibers•Two arrangements

– Irregular: Randomly-arranged fibers, e.g., joint capsules

–Regular: Parallel fibers, e.g., ligaments and tendons

DENSE CONNECTIVE TISSUE

2. DENSE CT

a. Irregular CT1) Like loose CT, but…

a)More fibersb)Fewer cells

2) Locations:a)Dermis of skinb)Submucosa of digestive tractc) Fibrous capsules of most

jointsd)Periosteum of bone e) Heart valves Continued…

b. REGULAR CT

1. Abundant, regular collagenous fibers

2. Location:1) Tendons2) Most ligaments3) Aponeuroses4) fasciae

3. Locations of some CT propers:

a. Mucus CT: Umbilical cordb. Elastic CT: walls of arteriesc. Reticular CT: blood pooling organsd. Adipose tissue: subcutaneous

tissue (hypodermis)e. Brown adipose tissue: Hypodermis

(between shoulder blades) of babies

ADULT CONNECTIVE TISSUES: CARTILAGE

1. General points:a. Avascularb. Temporary and permanent forms

(Collagenous and elastic fibers )c. Abundant matrix: cells

(chondrocytes) in holes (lacunae)d. Fibers embedded in chondroitan

sulfatee. Surrounded by perichondrium

Continued…

ADULT CONNECTIVE TISSUES: CARTILAGE

2. Three kindsa. Hyaline cartilage: location;

costal cartilage, nose, articular cartilage

b. Elastic cartilage: location; ear, auditory tube

c. Fibrocartilage; symphysis pubis

ADULT CONNECTIVE TISSUES: CARTILAGE

–Hyaline cartilage•Collagenous fibers not visible•Located at articulations•Forms costal cartilages,

respiratory passages•Forms most of embryonic skeleton

HYALINE CARTILAGE

ADULT CONNECTIVE TISSUES: CARTILAGE

–Elastic cartilage•Similar to hyaline, but with numerous elastic fibers

•Provides strength, maintains shape•Forms pinnae, epiglottis, auditory tubes

ELASTIC CARTILAGE

ADULT CONNECTIVE TISSUES: CARTILAGE

–Fibrocartilage•Similar to hyaline, but with

numerous collagenous fibers•Provides strength and rigidity•Forms pubic symphysis and

intervertebral discs

FIBROCARTILAGE

ADULT CONNECTIVE TISSUES: BONE

1. General points: – Makes up skeletal system– Very vascular– Supports, protects soft tissue– Provides for passive movement,

mineral storage, blood cell formation

– Osteocytes (cells) in lacunae (holes) in matrix

– Matrix consists of mineral salts and collagenous fibers

– Structural subunits are osteons

BONE (continued)

2. Kindsa. Spongy (cancellous) boneb. Compact bone: dense, ivory-like

BONE: ORGANIZATION

1. HAVERSIAN SYSTEMS (OSTEONS)

2. HAVERSIAN CANAL IN CENTER3. CONCENTRIC LAMELLAE OF

MATRIX4. LACUNAE CONNECTED BY

CANALICULI5. ONLY IN COMPACT BONE

–Osteons (Haversian systems)•Lamellae•Lacunae with osteocytes•Canaliculi•Central (Haversian) canal

ADULT CONNECTIVE TISSUES: BONE

OSSEOUS (BONE) TISSUE

Haversian canal

Lacuna with osteocyte

canaliculi

lamella

Bone Osseous tissue

ADULT CONNECTIVE TISSUES: VASCULAR

•Characteristics–Liquid or fluid connective tissue–Two components

•Plasma: Fluid•Formed elements: Cellular

– Erythrocytes– Leukocytes– Thrombocytes

ADULT CONNECTIVE TISSUES: VASCULAR

1. General pointsa. Most atypical CT: cells and

matrix are very different from other CT

b. Does not support mechanically, or connect things.

c. Two kinds: blood and lymph

ADULT CONNECTIVE TISSUES: VASCULAR

1. Blooda. matrix= plasmab. Cells (formed elements):

1. Erythrocytes (red blood cells; RBCs) anuclear, biconcave discs

2. Leukocytes (white blood cells; WBCs)

3. Thrombocytes (platelets)

ADULT CONNECTIVE TISSUES: VASCULAR

3. Lympha. Matrix = lymphb. Cells = white blood cells

VASCULAR CONNECTIVE TISSUE

ENDCONNECTIVE TISSUES

Connective TissuesConnective Tissues