BioMed Research International / 2013 / Article / Tab 1

Review Article

Morphogenetic Mechanisms in the Cyclic Regeneration of Hair Follicles and Deer Antlers from Stem Cells

Table 1

Overview of the comparisons between hair follicles and deer antlers.

Similarities
NatureHair follicleAntler unit
Mammalian organMammalian organ

Structure of mature organPermanent (infundibulum and isthmus) + cyclic (suprabulbar strand and bulb) componentsPermanent (pedicle) + cyclic (antler) components
OntogenyOrganogenesis and cyclic regenerationOrganogenesis and cyclic regeneration
Order of organogenesisPermanent component formed first and cyclic component formed secondPermanent component formed first and cyclic component formed second
Nature of ontogenyStem-cell-based (bulge cells)Stem-cell-based (AP and PP cells)
Location of stem cellsIn permanent componentIn permanent component
Initial identification of stem cellsThrough tissue graft and genetic marker (LacZ gene) labeling, but not tissue deletionThrough tissue graft and genetic marker (LacZ gene) labeling, but not tissue deletion
Attributes of stem cells Express embryonic stem-cell markers: Oct4, Nanog, and SOX2. Can differentiate into multiple cell lineagesExpress embryonic stem-cell markers: Oct4, Nanog, and SOX2. Can differentiate into multiple cell lineages
Location of growth centreIn the cyclic componentIn the cyclic component
Activation of generation and regenerationBy interactions between stem cells and the niche cell types (bulb cells)By interactions between stem cells and the niche cell types (skin cells)
Process of appendage sheddingEnzymes are involved in a proteolytic processEnzymes are involved in a proteolytic process
Endocrine control factorsMain factor: androgenMain factor: androgen
Paracrine control factorsMain factor: IGF1Main factor: IGF1
Molecules possibly involved in the interactions between stem cells and niche cellsIncluding canonical Wnt/β-catenin signaling, sonic hedgehog, and VEGFIncluding canonical Wnt/β-catenin signaling, sonic hedgehog, and VEGF
Molecules possibly involved in maintenance of stem-cell stemnessIncluding c-mycIncluding c-myc

Differences
Nature of organEpitheliumMesenchyme

Organ encapsulationA layer of mesenchymal tissueA layer of epithelial tissue
Order of structural componentsDistal, permanent, proximal, cyclicDistal, cyclic, proximal, permanent

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