MATERNAL HYPOTHYROIDISM AND CELL DEVELOPMENT IN CEREBELLAR CORTEX DURING FETAL AND POSTNATAL PERIOD IN THE RAT

Thyroids hormones (T3 and T4) play an important role in fetal and postnatal development. Deficiency of these hormones during fetal development which is caused by maternal hypothyroidism in early gestational period, results in severe damage to embryo especially to the central nervous system. In this investigation, 3-month-old female Wistar rats were used. The animals divided in two experimental and control groups. The experimental group was made hypothyroid by chemical thyroidectomy with propylthiouracil. From days 14 to 20 of gestation, some of the rats in experimental and control group were sacrificed and their embryos were collected for fixation. The same procedure was carried out for the brains of newborns from 1 to 20 postnatal days and some adults at 2.5 month of age. The brains of all specimens were processed, serially sectioned and stained for histological studies. The results showed that the numbers of purkinje cells in cerebellum decreased significantly in the experimental group. Furthermore there was a significant difference in their distribution between experimental and control groups. On the other hand the external granular cells, in the cerebellum of experimental group, remained until 5th week after birth or even during puberty. These data indicate that maternal hypothyroidism may result in severe damage in development of central nervous system during childhood and even at puberty.