Connective tissue, Cartilage & Bone Flashcards
❑ Holds, binds and support other tissue together
❑ Intercellular substance is the predominating component
❑ Most abundant with most numerous varieties
❑ Distinguished by the
❑ types and numbers of cells
❑ Nature of extracellular matrix
Connective tissue
glycoproteins or glycosaminoglycans, a gel like that fills the spaces between the fibers and cells; medium through which O2, nutrients and by-products diffuse
Ground substance
Normal cellular constituents
of connective tissue
Resident cells
Stellate or spindle shaped with cytoplasmic processes;
cells of the embryo which transform into different types of adult cells as
development progresses
Mesenchymal cells
Most common resident cells of loose c.t.; shape of the cells depend on their location in the connective tissue
Fibroblasts
Similar in form with the mesenchymal cells; mainly found in lymphatic organs where they produce reticular fibers
Reticular cells
- Rounded with bean or indented nucleus
- Also called histiocytes or
clasmatocytes –have varied shape, when crowded by other tissue components-they are angular and their nucleus is bean shaped
Macrophages
–size and shape vary greatly in different animals even within the same species
-nucleus rounded, central to
eccentrical in placement
- granules contain heparin and
histamine that cause inflammation (allergy)
Mast cells
Large multinucleated cells formed from the fusion of monocytes or
macrophages
Foreign body giant cells
Are of two types:
1. White adipose cells - appear like a signet ring with a
nucleus bulging slightly from one side of
the ring/cell
-in tissue section, adipose cells appear
empty because the fats are dissolved by
alcohol during processing
- Brown adipose cells- characterized by
numerous fat droplets thus, called
multilocular
- are mainly found in hibernating animals
Fat or adipose cells
Stellate cells occurring around (peri=around) a capillary or small vessel where they intimately in contact with the lining epithelium
Pericytes
Not normally
present in the c.t. but generally located in the circulating blood and they invade the c.t. when
the need arise
Transient cells
Sometime seen in plasma
cells which is an indication of degeneration of
the cells
Russel bodies
- pink-staining with H & E and appear as wavy bundles,
- most common and largest fibers
- strong and flexible, yet able to
resist stretch
Collagen Fibers
- Composed of elastin
- are long, thin, straight and branched fibers, when broken appears like corkscrew
- Stains more pink than collagen
fibers in H&E staining - stained with special stain such as
orcein or Weigerts resorcin fuschin
Elastic Fibers
- fibers are short and thin
interconnecting with each other
forming a net-like arrangement. - stained with silver (Argyrophilic)
- stained also with PAS
- Commonly found in lymphatic tissues
Reticular Fibers
This component of the connective tissue is very scant in amount except in blood (special type of connective tissue) where it comprises the greatest bulk
Fluids
Temporary in their existence, being present only in the developing
embryos
Embryonal connective tissues
Comprise the c.t. of growing and
adult animals
Adult connective tissue
- composed primarily of stellate mesenchymal cells embedded in a jelly-like amorphous substance
- found only in developing embryo
Mesenchymal connective tissue
- Found in wharton’s jelly of the
umbilical cord - Can be found also in the combs and wattles of birds and in the lamina propria of the omasum
Mucoid connective tissue
- Most common or ordinary
connective in the body; - Contains all the cells described before except the reticular cells
- Contains both the amorphous and formed intercellular substance
- Found in the subepithelial connective tissue (l.propria and t.
submucosa), - Mesenteries and in between muscles and nerves
Loose connective tissue
- Fibers are the predominant components
- Fibers are tightly arranged to make the tissue appear thick or dense
Dense connective tissue
–Characterized by the orderly arrangement
of the fibers; there two types:
- Collagenous connective tissue also known as the regular DWFCT-the few fibroblasts are arranged longitudinally in between parallel bundles of collagen
- found in tendons and ligaments and aponeurosis
- Elastic connective tissue is very similar to the regular DWFCT except that the predominant fibers are elastic which are branched
- present in the nuchal ligament, t. media of large (elastic) arteries
Regular dense connective tissue
Characterized by not orderly parallel array of collagenous fibers found in the dermis of the skin
Irregular dense connective tissue
Primarily composed of reticular fibers and is found in the fibrous stroma of lymphatic and blood forming organs
Reticular connective tissue
Actually areolar connective tissue containing pigment cells; found in the choroid and iris of the eye and connective tissue of pigmented skin
Pigmented connective tissue
Another variant of loose/areolar connective tissue
where the predominant cells are adipose cells
Adipose tissue
▪ Consists of cells and extensive
ECM of fibers and ground substance
▪ Avascular
▪ Covered by perichondrium
▪ Inner layer- chondrogenic layer (cellular)
▪ Outer layer- fibrous layer
Cartilage
The unit of cartilages
Chondron
Secrete the extracellular matrix (ECM) and become less active and contained in a space called lacuna
Chondroblast
Are the less active cells ,but maintain and repair the matrix of the cartilage cells
Chondrocytes
Multinucleated cartilage eating cells
Chondroclast
- Most common type
- Found in developing vertebrate skeleton, epiphyseal disc, articular cartilage, nose, larynx, trachea, bronchi ,ventral end of ribs
- Matrix contains collagenous fibers
o Interterritorial matrix
o Territorial matrix
• Isogenous group – clusters of 2
to 4 chondrocytes occupying the
same lacuna
HYALINE CARTILAGE
- Similar to the structure of hyaline but with numerous elastic fibers
- Found in epiglottis, parts of larynx and pinna, auditory tube, epiglottis
ELASTIC CARTILAGE
■ Transition of cartilage and connective tissue
■ Characterized by the “herringbone configuration” which is a “V shaped”
arrangement of the collagenous fibers
■ Also linear arrangement of chondrocytes, embedded in small amount of cartilage matrix, between bundles of collagenous fibers is
distinct
■ Found in the intervertebral disks and articular menisci, pubic symphysis, os cordis, tendons closed to bone
FIBROELASTIC CARTILAGE
- Cellular tissue embedded in a mineralized matrix component
- Covered by periosteum and
endosteum
Bone
The outer covering of the bone, composed of dense connective
tissue
Periosteum
The inner covering of osteogenic layer
Endosteum
It gives rise to osteoblast
Osteogenic stem cells
Basophilic cells, found on the surface of the bone where they deposit the organic (ground substance and fibers) inorganic components of the bone
Osteoblast
The mature osteoblast surrounded by bone matrix
Osteocytes
- The large, multinucleated cells, reabsorbed bone matrix during bone development and repair
- “Bone eaters”
Osteoclast
Unit structure of bone tissue
Osteon
Multiple layers of bone matrix
- Circumferential lamellae
- Concentric lamellae
Lamellae
Formed by concentric lamellae; oriented parallel to the long axis of the bone
Haversian system
Central canal; contains blood vessels and nerves
Haversian Canal
Transverse canal; connects vessels and nerves or periosteum, central canal and medullary cavity
Volksmann’s canal
Small space where the bone cells’ cytoplasmic process embed
Canaliculi
More space than bone matrix; formed by interconnected meshwork of spicules or trabeculae
Spongy Bones
More bone matrix than space; formed by densely packed layers of bone matrix with osteocytes
sandwiched in between layers;
Compact Bones
