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Thyroid gland of calves
GRÉK, Miloš
There were thyroid glands of 4 calves examined in this work. Calves were of the Holstein breed and were observed during the first 3 months of their life. Investigated parameters included levels of thyroid hormones and their relation to TSH, age related changes in Ca, Mg, P, protein, urea, triglyceride and gamma-glutamyltransferase (GMT) levels in blood plasma, length, width and perimeter of follicles and height of follicular cells. Mean total T4 content was 72,56+-17,76 nmol/l, T3 3,22+-1,04 nmol/l and TSH 0,94+-0,32 ng/ml. There was a positive correlation between the hormones and their free forms, and between T3 and TSH. T4 level rose with age, while T3 level fell. Protein and urea content rose with age as well, triglyceride and GMT content dropped. Ca, Mg and P content was relatively stable during the whole experiment. A higher number of small and medium sized follicles were observed in the thyroid glands. Mean follicle length was 86,24+-45,36 microns. Follicular cells reached a mean height of 7,95+-1,30 microns. All of the follicular parameters were highly individual, except follicular cell height.
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