الفهرس 
Introduction and Aim of the Work
The Anatomy of the Basal GangliaOnly 14 pages are availabe for public view
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Abstract
The basal ganglia include the caudate nucleus, the putamen, the globus pallidus and the claustrum. Also the substantia nigra and the subthalamic nucleus are considered as parts of the basal ganglia. The putamen consists largely of medium spiny neurons, which use gamma-aminobutyric acid astheir neurotransmitter. The subthalamic nucleus is a biconvex lens-shaped nucleus in the subthalamus of the diencephalon. The substantia nigra is a subcortical nucleus located in the midbrain that divided into the dorsal pars compacta with high content of pigmented dopaminergic neuronal cells, the ventral pars reticulata with fewer cells andthe smaller pars lateralis. Dopamine regulates direct and indirect pathway activity and modulates actions of the striatal neurons.
Iron is needed for the adequate development and functioning of the brain.Normal exposure to iron occurs through the diet and through occupational exposures from metal fumes and metal dust during welding and in iron industry. Iron enters the brain through the blood-brain barrier and the choroid plexus–cerebrospinal fluid barrier.Iron storage in the neurons of SN occurs through binding of iron within neuromelanin.The accumulation of iron in the substantia nigra pars compacta may be the key factor in pathogenisis of PD.
The aim of this study was to demonstrate the development of the neostriatum, the suthalamic nucleus and the substantia nigra pars compacta of the albino rat and detect the effect of iron overdoseduring the gestational and neonatal period on them.
Total125 rats were used in this study. Animals were divided into 2 groups;
A- Developmental group:was subdivided into 2 subgroups: 1- Control subgroup: 40 offspring rats were used. Ten rats for each age group were used at following ages; newborn, 10 days, 20 days and 2 months. The pregnant female rats received distilled water orally daily by means of gastric tube at the eighth day of pregnany till the 20th day postnatally. At the 21thday postnatally,offspring rats received distilled water orally daily by means of gastric tube till 2 months.2- Experimental subgroup:40 offspring rats were used.Ten rats for each age group were used at following ages; newborn, 10 days, 20 days and 2 months. The pregnant female rats received 15 mg/kgbw of Fe2+ by means of gastric tube at the eighth day of pregnany till the 20th day postnatally. At the 21th day postnatally,offspring rats received 15 mg/kgbw of Fe2+ daily by means of gastric tube till 2 months.
B- Adult group: Itwas subdivided into 2 subgroups: 1- Control subgroup: 10 rats were used.They receiveddistilled water daily through a gastric tube from the postnatal days 12th till three month. 2-Experimental subgroup: 10 rats were used. They received daily 15 mg/kgbw of Ferrous gluconate dissolved in distilled water daily through a gastric tube from the postnatal days 12th till three month. The rats were anaesthetized and the brains were extracted. The specimens from the fixed brains were dissected and processed for the light microscopic examination using Einersons gallocyanine stain. The immunohistochemical staining using anti Tyrosine hydroxylase (TH) of the putamen and SNc were done. The electron microscopic examination of the putamen and SNc was done. Morphometric measurements (the number of the neurons, the equatorial diameter and surface area of the somata of neurons in the putamen andSNc) were taken using an Image analyzer (Leica Q 500).
In this work, the results demonstrated that at different age experimental groups,the caudate nucleus and the putamen were ill-defined in comparison with the control. Apparently dilated lateral ventricle was noticed. The caudate nucleus was formed of packed deeply stained neurons and the intercellular spaces between the neurons were wider than that of the control. There was a separation between the caudate nucleus and the internal capsule at newborn experimental group and another separation between the putamen and the external capsule was observed at 10 days old experimental group. The putamen was contained amount of Nisslʹs granules less than that of the control. The intercellular spaces between the neurons were wider than that of the control at the same age. The putamen had darkly stained rounded neurons. Some neurons appeared with irregular outline. Shrunken deeply stained neurons were noticed. In 20 days old rat experimental group, the neurons showed lysis of the nuclei.The dilated congested blood vessels and many vacuolations were seen.
The neurons in the putamen at different age experimental groups showed heterochromatic nuclei and indentations of the nuclear membranes. Some neurons had nuclear degeneration at 10 days old experimental group. Other neurons appeared with lysis of the nuclei in 20 days old rat experimental group.
Examination of the synapses demonstratedan area of loss of the presynaptic and postsynaptic densities at different age experimental groups. Many synaptic vesicles were seen in the newborn experimental group, on the other hand in the successive ages minute number of the synaptic vesicles appeared. The mitochondria close to the synaptic terminal were destructed and showed breakage of its inner cristae and their walls were broken at several points at newborn, 20 days,2 months and 3months old experimental groups but normal mitochondria were seen at 10 days old experimental group.
Dilated blood vessels in the putamen of all different age experimental groups were seen. The pericytic microglia surrounding them showed big vacuolation, dilated rough endoplasmic reticulum and damaged mitochondria .The endothelial cells lining the blood vessels appeared dense at newborn, 10 days, 2 months and 3months old experimental groups. The dilated blood vessels with normal endothelial lining were observed at 20 days old experimental group.
Theputamen atnewborn and 10 days old experimental groups showed positive TH immunoreactive neurons but weaker than that of the control.In 20 daysold experimental group, many positive TH immunoreactive neurons and few negative TH immunoreactive neurons were observed. Considering 2 and 3 months old experimental groups, some areas with positiveTH immunoreactivity and many areas with negativeTH immunoreactivity were seen.
The subthalamic nucleus in the different age experimental groups consisted of deeply stained neurons with many vacuolations between them. The characteristic biconvex lens shape of the subthalamic nucleus was disturbed at 20 days, 2 and 3 months old groups.
The substantia nigra appeared at newborn experimental group on the dorsal surface of the cerebral peduncle as layer of packed neurons thinner than that of the control. SNc at 10 days old experimental group appeared as thin incomplete layer of packed neurons with vacuolations and the neurons showed varied stages of pyknosis and degeneration. SNc at 20 days, 2 and 3 months old experimental groups showed apparently increased interstitial spaces between neurons with many vacuolations and a decreased in the number of the neuronal perikarya as compared with the control. The neurons had dense nuclei, irregular outlines and intensely stained cytoplasm.
Shrunken neurons with peripheral condensation of the chromatin of their nuclei were seen inSNc. Many vacuolations are detected. Extravasation of blood cells separating neurons was observed in the midbrain. Some neuronsof SNc at newborn experimental group appeared normal. The neurons in 10 days old experimental group showed the nuclei with degenerated part of it.Some neurons had the nuclei with peripheral condensation of chromatin and their cytoplasm showed marked loss of the cell organelles and many vacuoles at different age experimental groups.The synapse showed loss of the presynaptic and postsynaptic areas with minute numbers of synaptic vesicles. The damaged mitochondria appeared with widened inner spaces and points of breakage.
At newborn rat experimental group,thepositivity of TH immunoreactive neurons in thesubstantia nigra was less than that of the control. The neuronal processes appeared at first time in 10 days old control group.In 10 days old experimental group,SNc had a decrease in positive TH immunoreactivity than that of the control of the same age. SNc revealed wide areas of negative TH immunoreactivity and decreased in the number of TH immunopositive neurons at 20 days, 2 and 3 months old groups.
Morphometric study in the present work showed that the number of the neurons in the putamenand SNc in albino rat at different age control groups showed a significant decrease from newborn to two months agecontrol group and the longitudinal diameter of the neurons in the putamen and SNc showed a significant increase from newborn to two months agecontrol group. Also morphometric study revealed that the putamen andSNcof the experimental group showed an insignificant decrease in the number of neurons at the ages of newborn and 10 days while it showed a significant decrease at 20 days,2and 3months. Considering the surface area of the neuron in the putamen experimental group showed an insignificant decrease at the ages of newborn and 10 dayswhile it showed a significant decrease at 20 days, 2 and 3 months.