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Abstract Diabetes mellitus is a syndrome of disturbed energy hemostasis , caused by deficiency of insulin or of its action and is manifested by abnormal metabolism of carbohydrate , fat , protein , water and electrolytes . Diabetes mellitus is classified into two types ; primary and secondary diabetes mellitus . In this study one hundred and twenty rats were used and classified into two groups ; experimental and control.The experimental group consisted of sixty rats and were divided into two subgroups ; prenatal and postnatal . The prenatal subgroup was obtained by giving the mothers in the first day of pregnancy a single dose of 50 mg per kilogram body weight of streptozotocin intraperitoneally to make them severely diabetic . Twenty fetuses were taken on the 14th and 20th day of gestation , in each age group ten fetuses were used to study the effect of diabetes mellitus on the prenatal development of the nervous system . The postnatal subgroup consisted of forty offspring . They were immediately given after delivery a single dose of 50 mg per kilogram body weight of streptozotocin intraperitoneally . They were taken at four stages; one week, two weeks, three weeks and eight weeks . 167 At each sage, ten rats were used to study the effect of diabetes on the postnatal development of the nervous system . The control group also consisted of sixty rats and were divided into prenatal and postnatal subgroups . The first consisted of twenty fetuses while the second consisted of forty offspring . At ages similar to those of the experimental subgroups , ten fetuses or offspring were taken . from both experimental and control groups, the brains, spinal medulla and sciatic nerves were extracted , then prepared for microscopic examination using haemtoxylin :end eosin , .cresyl violet , thionine and silver stains . In addition , Golgi-Cox technique was only used for the third and fourth postnatal subgroups from this work , it was found that diabetes mellitus has hazardous effects on the development of the nervous sytem both in the pre- and post-natal peroids . In prenatal peroids , morphologically the cerebellum showed slowing in organization into folia . It also showed marked decrease in the thickness of the external granualr layer , an apparent decrease in cellular density of both molecular and internal granular layers with loss of Nissl granules and disorientally arranged Purkinje cells . In postnatal peroids , the cerebellum also showed marked slowing in its organization into folia especially during the early ages 168 with marked decrease in the thickness of the external granular layer . The molecular layer showed an apparent decrease in cellular density The Purkinje cells were disorientally arranged in early ages and became rounded and smaller at older ages . In the cerebral cortex , there was no apparent morphological changes at all ages . However, serious affections in the cerebral cortex were observed . In the prenatal petoids , there were degenerative and necrotic changes with ventricular haemorrhage . The cerebral cortex in the postnatal peroids showed the same prenatal affections at early ages. The observed thickening of blood vessel walls and regeneration by gliosis were observed at older ages . MorpholOgically the spinal medulla in the prenatal peroids was horizontally enlarged , the grey matter became larger especially the posterior horn and the white matter appeared as a thin rim . The central canal was narrowed and displced ventrally with subarachnoid haemorrhage . The grey matter showed areas of necrosis and degeneration with loss of Nissl granules . In the postnatal peroids, beside these prenatal affections , the central canal became dilated and the cells in the grey matter became small in size with multiple empty spaces in the white matter . Nerve fibres in the sciatic nerve became thin in 169 both pre- and postnatal peroids with thickening of the blood vessel walls in the epineurium and narrowing of its lumen . B- Conclusion : from the above observed findings , it could be concluded that diabetes mellitus has serious degenerative effects on the prenatal development of the nervous system. Diabetes mellitus has also severe degenerative changes on the postnatal development of the nervous system especially the cerebral cortex and spinal medulla but the prenatal influence was found to be more serious . With longer duration of diabetes mellitus , the degenerated nervous tissues were replaced by gliosis . Therefore , it is advisable that all pregnant diabetic mothers should attend the antenatal clinic for control of their blood sugar levels . |