Histology - Specialized Connective Tissues (BONE)

SPECIALIZED CONNECTED TISSUE:BONE

Clara CorpuzEmsi Cipriano

Jacob Dela Cruz

BONE TISSUE Bone Matrix: consists of cells, fibers

and ECM made up of type 1 collagen Highly vascular + Mineral deposition: Bone →

Calcified Bear more wt Withstand stress Provide attachment sites for

muscles and organs Hematopoiesis Storage of Ca+2 and phosphate

BONE MATRIX Bone Matrix: consists of cells, fibers

and ECM made up of type 1 collagen Organic components: sulfated

glycosalmiglycans and hyaluronic acid → larger proteoglycan aggregrates Mineralization: Glycoproteins osteocalcin and

osteopontin bind to calcium Sialoprotein binds osteoblasts to ecm through integrins

of plasma membrane Inorganic components:

Calcium + phosphate = hydroxyapatite crystals + collagen fibers = bone hardness durability strength

BONE CELLSOsteoprogenitor cells:

undifferentiated, pleuropotential stem cells

Osteoblasts: @ surface of the bone that synthesize, secrete bony matrix; active

Osteocytes: mature form of osteoblasts; maintain the structural integrity of the matrix

Osteoclasts: resorb bone during remodeling

PROCESS OF BONE FORMATION

Endochondrial OssificationIntramembranous Ossification

Endochondral OssificationHyaline Cartilage → Interstital and

Appositional Growth → Chondrocytes divide and enlarge → Cartilage Calcify → diffusion of nutrients ↓ chondrocytes die fragmented → calcified matrix → Periosteum → osteoprogenitor cells (arise from endosteum) and bv invades → Osteoblasts

Mesenchyme + Osteoblasts + Bv = Ossification center

Long bones: primary ossification center in diaphysis → secondary in epiphysis → Osteoid Matrix → bone (x epiphyseal plate region)

INTRAMEMBRANOUS OSSIFICATIONNo cartilageforms the mandible, clavicles,

and flat bones of the bodyMesenchyme → Osteoblasts →

osteoid → calcified → osteocytes w/ lacunae

Two Kinds of Bone

Compact bone

Spongy Bone

Spongy BoneAlso called cancellous or

trabecular boneNo formal osteonsTrabeculaeForms most of the structure of

short, flat, and irregular bones, and the epiphyses of long bones.

Spongy bone (Trabeculae)Latticework of thin plates of bone

oriented along lines of stressContains red bone marrow

(hemopoiesis)Found in ends of long bones and

inside flat bones such as the hipbones, sternum, sides of skull, and ribs.

Red bone marrow in spongy bone

Slide Observed under LPO

Two Kinds of Bone

• Compact Bone

• Spongy Bone

Histology of Bone Tissue

Compact Bone• The structural unit of compact bone

is the osteon or Haversian system.• Each osteon is an elongated cylinder

running parallel to the long axis of the bone.

• It actually contains canals and passageways that provide access for nerves, blood vessels, and lymphatic ducts.

• Each columns is made up of concentric rings or lamellae along the calcified matrix.

Concentric layers or rings along the calcified matrix.

Tiny cavities inside the lamellae. This is the space where the osteocyte are found.

It is the central canal that is surrounded by concentric lamellae.

Tiny hair-like channels that are branching.

Compact Bone

• Connects two Haversian canals.

• Canals lie at right angles to long axis of bone.

• Connect the vascular supply of the periosteum to those of the central canal and medullary cavity.

Volkmann’s canal

Histology of Bone Tissue

Canaliculi

Haversian canal

Circumferencial lamellae

Osteocyte surrounded by lacuna

Interstitial lamellae

Haversian system/Osteon

OIODecalcifiedhuman bone

REFERENCESDifiores’ Atlas of Histology 11th

Ed.http://www.freezingblue.com/

iphone/flashcards/printPreview.cgi?cardsetID=266224

http://www.wisegeekhealth.com/what-is-spongy-bone.htm

http://www.gla.ac.uk/t4/~fbls/files/fab/tutorial/generic/bone2.html