Estimation of the C-cell numbers in rat thyroid glands using the optical fractionator.
We estimated the total number of calcitonin-immunoreactive C-cells in rat thyroid gland using the optical fractionator, the unbiased stereological method for estimation of numbers. It was necessary first to use a fixative composed of formalin, acetic acid, and ethanol to distinctly visualize the C-cells. The 40-microm-thick sections had to adhere to chromalum-gelatin-coated Superfrost Plus glass slides, and the immunostaining technique had to stain the C-cells evenly throughout the whole sections. Because the C-cells were irregularly distributed in the thyroid tissues, their counting required screening of about 500 fields per lobe, but the number of C-cells counted need not be high, about 90 per lobe. We estimated that rats have 185,000 +/- 42,000 C-cells (mean +/- SD; n - 7). The C-cell population did not differ significantly between the two lobes of a given rat, but it varied markedly among rats. The biological differences among the animals contributed 83% to the observed variability, whereas the methodological uncertainty contributed 17%. The serum levels of calcitonin and calcium were not closely correlated to the C-cell numbers. Our results indicate that variability in C-cell experiments can be reduced most effectively by increasing the number of animals used. However, the similar C-cell frequency found in the two thyroid lobes of each rat allows the use of one uniformly sampled lobe for quantification and the other lobe for further analysis.
Feinstein
R E
RE
Department of Pathology, The National Veterinary Institute, Uppsala, Sweden.
Westergren
E
E
Bucht
E
E
Sjöberg
H E
HE
Grimelius
L
L
D000818:Animals; D002116:Calcitonin / Q000276:immunology; D002118:Calcium / Q000378:metabolism; D002452:Cell Count / Q000379:methods*; D005591:Chemical Fractionation / Q000295:instrumentation; D005260:Female; D007150:Immunohistochemistry / Q000379:methods; D055095:Optics and Photonics / Q000295:instrumentation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013961:Thyroid Gland / Q000166:cytology* / Q000378:metabolism
D002116:Calcitonin; D002118:Calcium