Inclusion bodies in pinealocytes of the cotton rat (Sigmodon hispidus) - An ultrastructural study and X-ray microanalysis

Michal Karasek, Nancy K.R. Smith, Thomas S. King, Larry J. Petterborg, John T. Hansen, Russel J. Reiter

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Pinealocytes of the cotton rat (Sigmodon hispidus) often contain large (2-6 μm diameter) intracytoplasmic inclusions, the function of which is not known. These inclusions may represent nucleolus-like bodies, mineral deposits, secretory products or viral inclusions. In this study these inclusions were classified as type A, B or C inclusions based on the amount of electron-dense material interspersed within the finely granular material comprising the bulk of these inclusions. Each type of inclusion was analyzed by X-ray microanalysis and enzymatic protein-aceous digestion. X-ray microanalysis of these inclusions differed both quantitatively and semiquantitatively from that of human or gerbil pineal concretions, the latter two of which are extracellular deposits. Pronase, a proteolytic enzyme, digested the electron-dense material only after longer times of tissue exposure to this enzyme in contrast to the easily digested, finely granular matrix-like material of these inclusions. Such intrapinealocytic inclusions have only been observed in the cotton rat. Their functional significance remains unknown.

Original languageEnglish (US)
Pages (from-to)413-420
Number of pages8
JournalCell and Tissue Research
Issue number2
StatePublished - Jul 1 1983


  • Cotton rat
  • Inclusion bodies
  • Pinealocytes
  • Protein digestion
  • X-ray microanalysis

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Histology
  • Cell Biology


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