strength, and mechanical support to plant structure.
Also part of sclerenchyma tissue, which is thickened
cell walls of lignin, composed of both sclereids, short
cells, and the longer fibers, and lacking a living proto-
plast when mature.
In human nutrition, fiber is a carbohydrate that
resists the action of digestive enzymes and passes
through the human digestive system virtually
unchanged, without being broken down into nutrients.
There are insoluble fibers, found in wholegrain prod-
ucts and vegetables, that help the digestive system by
moving stools through the digestive tract by keeping
them soft. Soluble fiber slows the digestive process and
is water-soluble. Found in beans, fruits, and oat prod-
ucts, it is thought to help lower blood fats and blood
glucose (sugar).
Fiber is also a slender, elongated natural or syn-
thetic filament capable of being spun into yarn, e.g.,
cotton.
Fibiger, Johannes Andreas Grib (1867–1928) Dan-
ishPathologist Johannes Andreas Grib Fibiger was
bornin Silkeborg, Denmark, on April 23, 1867, to C.
E. A. Fibiger, alocal medical practitioner, and Elfride
Muller, awriter.
Fibiger studied under bacteriologists RobertKOCH
and Emil von Behring, and from 1891 to 1894 he was
assistant to Professor C. J. Salomonsen at the depart-
ment of bacteriology at the University of Copenhagen.
He received his doctorate from the University of
Copenhagen in 1895 based on research into the bacte-
riology of diphtheria.
He was appointed prosector at the university’s
Institute of Pathological Anatomy (1897–1900), princi-
pal of the Laboratory of Clinical Bacteriology of the
Army (1890–1905), and in 1905 became the director
of the central laboratory of the army and consultant
physician to the Army Medical Service.
Fibiger’s early research dealt with diphtheria
and tuberculosis, and he developed laboratory
methods for growing the causing bacteria as well as
a serum to protect against the disease. Fibiger
achieved the first controlled induction of cancer in
laboratory animals, after research in studying tumors
in the stomachs of animals, by feeding mice and
rats with cockroaches infected with a worm. His
work led others to pursue the research on chemical
carcinogens and led to the development of modern
cancer research.
Fibiger was a founding member and joint editor of
the Acta Pathologica et Microbiologica Scandinavica,
and coeditor of Ziegler’s Beiträge zur pathologischen
Anatomie und zur allgemeinen Pathologie.He received
the 1927 Nobel Prize in physiology or medicine for his
work on cancer, specifically for his “discovery of the
Spiroptera carcinoma.” Fibiger died on January 30,
1928, in Copenhagen.fibril A small or microscopic thread of cellulose that
is part of the cellulose matrix of plant cell walls. The
contractile unit of a muscle cell or a bundle of filaments
in a striated muscle cell; the thin fibrous structure of a
nerve; a long fine hair or fiber; many fibrils bundle
together to form a fiber. Makes up the smallest unit of
paper fibers. Also a linear feature in the H alpha chro-
mosphere of the Sun, found near strong sunspots and
plages or in filament channels. Fibrils parallel strong
magnetic fields.fibrin An insoluble stringy protein derived from fib-
rinogen that facilitates blood clotting by forming
threads and creating the mesh around the clot. A blood
clot is also called a fibrin clot. Coagulation begins usu-
ally with an injury to some part of the body. The body
forms a clot from a mixture of the blood protein fibrin
and platelets. After the bleeding stops, a blood protein
dissolves the clot by breaking down the fibrin into tiny
fragments.fibroblast(fibrocyte) A flat, elongated, branched,
irregular and motile cell type found in vertebrate con-
nective tissue that produces extracellular collagen and
elastin fibers; spindlelike with long cytoplasmic exten-
sions at each end and with oval, vesicular nuclei; most
abundant cell type found in the skin. Fibroblasts differ-
entiate into chondroblasts that secrete cartilage matrix,
collagenoblasts that proliferate at chronic inflammation
sites, and osteoblasts that secrete bone matrix. They
form the fibrous tissues in the body, tendons, and
aponeuroses, the shiny, broad sheets of connective tis-
sue that bind muscle fibers together to form muscles, as
well as supporting and binding tissues.128 Fibiger, Johannes Andreas Grib