In the present paper we describe changes of anatomical parameters in inbred Lewis strain rats, namely their body weight, body weight gain per week, absolute and relative heart, thyroid gland and skeletal muscle weights, that are assumed to reflect experimentally altered thyroid status. The hyperthyroid state was induced by DL-thyroxine or Na 3,3',5-triiodo-L-thyronine, while methimazole was employed for inducing hypothyroidism. We have found that when compared to euthyroid rats, hypothyroidism resulted in a significantly lower body weight gain, absolute and relative heart weight and, in contrast, in a significant increase of absolute and relative thyroid gland weight. On the other hand, hyperthyroidism led to a significant increase of absolute and relative heart weight and to a significant reduction of absolute and relative thyroid gland weight. However, the body mass was not significantly altered in hyperthyroidism as compared with euthyroid rats. We conclude that our protocol leads to chronic hyper- or hypothyroidism as demonstrated by body, heart and thyroid gland weight changes. These anatomical data can thus be utilized as supplemental criteria for the assessment of the thyroid state of experimental rats., T. Soukup, G. Zachařová, V. Smerdu, I. Jirmanová., and Obsahuje bibliografii
The objective of the current study is to present data on the
splitting of skeletal muscle fibers in C57BL/6NCrl mice. Skeletal
muscles (m. rectus femoris (m. quadriceps femoris)) from 500
(250 ♀ and 250 ♂) C57BL/6NCrl mice in the 16th week of life
were sampled during autopsy and afterwards standardly
histologically processed. Results show spontaneous skeletal
muscle fiber splitting which is followed by skeletal muscle fiber
regeneration. One solitary skeletal muscle fiber is split, or is in
contact with few localized splitting skeletal muscle fibers. Part of
the split skeletal muscular fiber is phagocytosed, but the
remaining skeletal muscular fiber splits are merged into one
regenerating skeletal muscle fiber. Nuclei move from the
periphery to the regenerating skeletal muscle fiber center during
this process. No differences were observed between female and
male mice and the morphometry results document <1 % skeletal
muscle fiber splitting. If skeletal muscular fibers splitting occurs
5 %> of all skeletal muscular fibers, it is suggested to describe
and calculate this in the final histopathological report.