title: Thyroid regeneration: characterization of clear cells after partial thyroidectomy.
abstract: Although having the capacity to grow in response to a stimulus that perturbs the pituitary-thyroid axis, the thyroid gland is considered not a regenerative organ. In this study, partial thyroidectomy (PTx) was used to produce a condition for thyroid regeneration. In the intact thyroid gland, the central areas of both lobes served as the proliferative centers where microfollicles, and bromodeoxyuridine (BrdU)-positive and/or C cells, were localized. Two weeks after PTx, the number of BrdU-positive cells and cells with clear or faintly eosinophilic cytoplasm were markedly increased in the central area and continuous to the cut edge. Clear cells were scant in the cytoplasm, as determined by electron microscopy; some retained the characteristics of calcitonin-producing C cells by having neuroendocrine granules, whereas others retained follicular cell-specific features, such as the juxtaposition to a lumen with microvilli. Some cells were BrdU-positive and expressed Foxa2, the definitive endoderm lineage marker. Serum TSH levels drastically changed due to the thyroidectomy-induced acute reduction in T(4)-generating tissue, resulting in a goitrogenesis setting. Microarray followed by pathway analysis revealed that the expression of genes involved in embryonic development and cancer was affected by PTx. The results suggest that both C cells and follicular cells may be altered by PTx to become immature cells or immature cells that might be derived from stem/progenitor cells on their way to differentiation into C cells or follicular cells. These immature clear cells may participate in the repair and/or regeneration of the thyroid gland.
authors.affiliation: Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Takashi
authors.initials: T
authors.lastname: Ozaki
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Matsubara
authors.forename: Daekwan
authors.initials: D
authors.lastname: Seo
authors.forename: Minoru
authors.initials: M
authors.lastname: Okamoto
authors.forename: Kunio
authors.initials: K
authors.lastname: Nagashima
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Sasaki
authors.forename: Suguru
authors.initials: S
authors.lastname: Hayase
authors.forename: Tsubasa
authors.initials: T
authors.lastname: Murata
authors.forename: Xiao-Hui
authors.initials: XH
authors.lastname: Liao
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Hanson
authors.forename: Jaime
authors.initials: J
authors.lastname: Rodriguez-Canales
authors.forename: Snorri S
authors.initials: SS
authors.lastname: Thorgeirsson
authors.forename: Kennichi
authors.initials: K
authors.lastname: Kakudo
authors.forename: Samuel
authors.initials: S
authors.lastname: Refetoff
authors.forename: Shioko
authors.initials: S
authors.lastname: Kimura
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D005260:Female; D008297:Male; D051379:Mice; D012038:Regeneration / Q000502:physiology*; D013961:Thyroid Gland / Q000166:cytology / Q000502:physiology* / Q000601:surgery; D013965:Thyroidectomy