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9.11 Microenvironment, Hyaluronan-Rich Matrix,
of the Maculae Flavae as a Stem Cell Niche
in the Human Vocal FoldThe structural and biochemical microenvironment that confers stemness upon cells
in multicellular organisms is referred to as the stem cell niche. A stem cell niche is
composed of a group of cells in a special tissue location for the maintenance of stem
cells (Li and Xie 2005 ).
Hyaluronan serves as an important niche component for numerous stem cell
populations (Haylock and Nilsson 2006 ; Preston and Sherman 2011 ). After the
discovery of hyaluronan, it was assumed that its major functions were in the bio-
physical and homeostatic properties of tissues. However, current studies lead to
understanding that hyaluronan also plays a crucial role in cell behavior (Toole
1991 ). A hyaluronan-rich matrix, which is composed of the glycosaminoglycan
hyaluronan and its transmembrane receptors (cell surface hyaluronan receptors), is
able to directly affect the cellular functions of stem cells in a stem cell niche
(Haylock and Nilsson 2006 ; Preston and Sherman 2011 ).
The maculae flavae in the human adult vocal fold are strongly stained light
blue with Alcian Blue at pH 2.5 (Fig. 9.4). The materials in the maculae flavae that
are strongly stained with Alcian Blue (pH 2.5) are digested by hyaluronidase.
A great deal of glycosaminoglycan (hyaluronan) is situated around the cells in the
human adult maculae flavae and hyaluronan concentration is high. The border
between dense masses of hyaluronan (macula flava) and the surrounding tissue is
Fig. 9.4 Coronal section of
the posterior macula flava
(Alcian blue stain, pH 2.5)
K. Sato