[Effects of thyroid hormones and heat value restriction of food intake on the glial surrounding and soma development of Purkinje cell (author's transl)].

Hyper- and hypothyroidism repercussions on soma, nucleus and cytoplasm increases were studied by electron microscopy on 7-, 14-, 21-, and 35-day-old rats. Adult normal animals were compared with adult ones made hypothyroid until they were 35 days old. Also heat value restriction of food intake effects were compared with hypothyroid ones at 14 and 35 days. Hyperthyroidism accelerated the soma and cytoplasm size increase as early as 14 days, and the nucleus size increase as early as 21 days. It did not change the nucleo-cytoplasmic ratio (N/P) markedly, except that maximal value of this ratio was reached earlier than in normal animals. Heat value restriction of food intake led to a transitory soma size decrease at 14 days and a high nucleus size increase. This diet did not change markedly either cytoplasm size or N/P ratio value. Hypothyroidism slackened the rate of the soma, nucleus and cytoplasm size increase during the third postnatal week especially. Beyond, these structures went on increasing and their size became greater than normal in adult hypothyroid animals. N/P ratio was always superior to normal. Hypothyroidism led to a high volumetric and linear density of Purkinje cell soma glial surrounding. Hyperthyroidism caused a slight increase of these parameters which were not greatly changed by heat value restriction of food intake.