Loose Connective Tissue

(LCT)

Areolar Tissue

Pink = collagen

Purple = elastin

Masson’s Trichrome Stain – blue = collagen

Orecin Stain for Elastin – purple “ribbon candy”

Sliver Stain for Reticular Fibers

Collagen synthesis

and organization

TEM of extracellular collagen fibers (Cl)

TEM of collagen fibers with 64 nm periodicity

Glycosaminoglycan Structure

Proteoglycan

A schematic representation of a proteoglycan. It consists of a protein core molecule bound with many different types of Glycosaminoglycans (GAGs).

For example, a proteoglycan from cartilage matrix can have 30 keratan sulfate and 100 chondroitin sulfate GAG chains.

Aggregan – the largest extracellular proteoglycan complex

Core hyaluronic acid (GAG in blue) complexed with numerous proteoglycans .

Aggregan – the largest extracellular proteoglycan complex

Core hyaluronic acid (GAG in blue) complexed with numerous proteoglycans .

PAS stain of epithelial basement membranes (BM)

TEM of a basement membrane (BL)

Diagram of the Basal Lamina

Laminin

Nidogen

Heparan Sulfate

PGsCollagen Type IV

Basal cell memb w/ Integrins

Cells of the LCT

Fibroblasts

LM of fibroblasts (arrows)

SEM of fibroblasts

Live fibroblasts in culture – viewed with phase microscopy

SEM image of a long fibroblast cell projection in culture

Adipose and Adipocytes

Adipocytes (fat cells)

Adipose Tissue – fat cells + CT septa (arrows)

Adipose Tissue fixed and stained w/ Osmium Tetroxide

Defense cells of the LCT

Neutrophils, Plasma cells, Mast cells, and Macrophage

LCT – a = pericytes; b = mast cell; c = plasma cells; d = capillary

LCT – M = mast cell; P = plasma cells; F = fibroblasts; Eo = eosinophils, N = neutrophils

TEM of a Plasma Cell

TEM of a Mast Cell

TEM of a Macrophage