Biophotonics_Concepts_to_Applications

cavity inside the body), connective tissue, nervous tissue, and muscle tissue. Organs
in the body are composed of a layered combination of these basic tissues. As an
example, within the esophagus thefirst layer of the esophageal wall contains
epithelial cells, as Fig.6.10shows. Covering this epithelium layer is connective
tissue and several layers of smooth muscle cells. Glands, nervefibers, and blood
vessels run through the connective and muscle tissues.

Epithelium (cellular

covering of the

inner surface)

Smooth muscle

(2 or 3 layers)

Connective tissue

(contains glands,

blood vessels, nerves)

Connective tissue

(supports and binds the

esophagus to other organs)

Organ

cavity

Fig. 6.10 Layered combination of basic organ tissues

10 μm

1 μm

100 nm

10 nm

Rayleigh

scattering

Eukaryotic cells (10-100 μm)

Size scales Types of scattering

elements and their sizes

Nucleus (5-10 μm)

Mitochondria (prolate spheroid:

1-2 μm length; 0.2-0.8 diameter)

Lysosomes (250-800 nm sphere)

Collagen fibrils (300 nm × 1.5 nm cylinder)

Macromolecules: cellulose, proteins, polypeptides

(2 – 100 nm)

Cell membranes (7 nm)

White blood cells (7-20 μm spheroids)

Red blood cells (biconcave dish: 7.8 μm diameter)

Golgi apparatus 100-400 nm)

Wavelengths used

in biophotonics

Infrared

UV

Fig. 6.11 Sizes of scattering elements in biological tissue

6.3 Scattering 161