CYTOLOGICAL RESPONSES OF BROWN FAT TISSUE IN COLD-EXPOSED RATS.

I. L. CAMERON, R. E. SMITH

Research output: Contribution to journalArticlepeer-review

80 Scopus citations

Abstract

In young adult laboratory rats exposed to cold (6 degrees C) the brown adipose tissue undergoes time-dependent increases in cellularity, vascular supply, and total mass. These changes are largely complete after 16 days in the cold and concurrent generally with the development of a thermoregulatory state not greatly dependent upon shivering. Histologically the brown fat changes from a tissue having both unilocular and multilocular fat cell types to one having almost exclusively the latter. During the first 6 to 12 hours in cold, the multilocular cells lose their lipid vacuoles and decrease in size, but these features are restored to normal by 24 hours. Cell proliferation, as estimated by the DNA synthetic index method (using tritiated thymidine autoradiography), appears in the reticuloendothelial cells of the brown fat at 1 day of cold exposure, becomes maximal at 4 days, and returns to the control level by 16 days. In animals injected with tritiated thymidine on the 3rd day of cold exposure and then maintained for 1 or more additional days in the cold, autoradiographs indicate that new brown fat (multilocular) cells arise by cytogenesis from reticuloendothelial progenitor cells and not by proliferation of existing brown fat cells. Throughout this and subsequent periods, cells of the epididymal white adipose tissue slowly decrease in size. Because a thermogenic role in cold acclimation has been established for the brown fat, the reported changes are regarded as adaptive responses to a cold environment.

Original languageEnglish (US)
Pages (from-to)89-100
Number of pages12
JournalThe Journal of cell biology
Volume23
DOIs
StatePublished - Oct 1964
Externally publishedYes

ASJC Scopus subject areas

  • Cell Biology

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