Carys M. Bannister

Ventricular ependyma of normal and hydrocephalic subjects: a scanning electronmicroscopic study.

Recent scanning electronmicroscopic studies of the ependymal surfaces of the lateral, third and fourth ventricles of a variety of animals have shown that most areas are covered by numerous cilia. In this paper, the density of the ciliary population in each of the ventricles is illustrated with material taken from human and rat brains.

The fine structure of the axonal torpedo in Purkinje cells of the human cerebellum.

Axonal torpedoes on Purkinje cells of the cerebellum have been observed at electron microscopic level in the case of a 5-year-old boy suffering from juvenile astrocytoma present in the roof of the fourth ventricle and cerebellar hemisphere. The axon torpedo is characterised by a central accumulation of disoriented neurofilaments, which displace the mitrochondria and endoplasmic reticular elements to the periphery. The mitochondria are small and densely staining with longitudinally arranged cristae and are intimately associated with the smooth endoplasmic reticulum that occurs as stacked complexes. Multivesicular and lamellar bodies, typical of degenerating axons, are not consistently seen and this indicates that axon torpedoes are more likely to represent a regenerating state within the nerve fibre than a degenerative condition.

CT observations on the natural history of asymptomatic cerebral infarction following transient ischaemic attacks

Two hundred and sixty-one neurologically asymptomatic patients were examined by computed tomography (CT) following a variable number of transient ischaemic attacks (TIAs) experienced over different time intervals. Cerebral infarcts were discovered in 101 patients. Dominant hemisphere infarcts were usually small, of recent origin and most often associated with less than 5 TIAs and a short history; whereas non-dominant hemisphere infarcts were found twice as frequently and were larger and older and correlated with repeated TIAs over many months. All infarcts, independent of size, were confined to a single vascular territory, suggesting haemodynamic rather than embolic causes. By comparing the age and size of the infarcts with the number of TIAs and their chronicity, the hypothesis emerged, suggesting that infarcts may occur early on and progressively enlarge with repeated attacks.

NUCLEAR INCLUSIONS IN ALZHEIMER'S DISEASE

Toper S., Bannister CM., Lincoln J., Mann D.M.A. & Yates P.O. (1980)

Ischemia and revascularization of the middle cerebral territory of the rat brain by manipulation of the blood vessels in the neck

Ischemia of the middle cerebral territory in the rat brain has been produced by anastomosing the right common carotid artery to the right jugular vein, and occluding the left internal and common carotid arteries. Revascularization is performed by ligating the right common carotid artery distal to the arteriovenous anastomosis and removing the clips from the left carotid arteries. The majority of the rats made ischemic deteriorated progressively and died if revascularization was not carried out, but only 10% of them died if the operation was performed within one hour, although the rate rose to 90% if the operation was delayed for 4 hours.

Long-term effects of heparin on veins grafted into the common carotid arteries of rats--a scanning electron microscopic study.

Jump grafts made from veins with diameters of about 1 mm have very poor patency rates. Dissection and anastomosis damage the endothelia of the arteries and veins and expose collagen in the subendothelial layers of these vessels. Within 1 hr of the introduction of blood flow through the grafts, deposits of fibrin and platelets led to blockage of the grafts. In 9 rats, heparin was given intravenously about 0.5 hr before completion of the grafting procedure; heparin was also used to wash out the veins for grafting. In 11 rats, heparin was used only to wash out the veins for grafting. At periods 1-11 weeks later, the grafts were reexamined. All were patent except 1 from the first group, examined at 7 weeks, and 1 from the second group, examined at 10 weeks. Scanning electron microscopy showed that complete healing of the venous endothelium took several weeks. Heparin was equally effective in keeping the grafts patent when given intravenously and used locally or when only used locally. This study indicates, therefore, that long-term patency in small diameter vein grafts can be achieved merely by washing out the veins for grafting with a solution of heparin.

RESPONSE OF THE FETAL RAT BRAIN TO TRAUMA DURING THE 17th TO 21st DAYS OF GESTATION

Ultrasonography has made it possible to diagnose abnormalities of the human central nervous system early in pregnancy. However, more needs to be known about the response of the fetal brain before the mother and fetus are subjected to the risks of complex neurosurgical procedures. This study investigated the effects of trauma on fetal rat brains during a period equivalent to the early part of the second trimester of human pregnancy. Trauma inflicted on the fetal rat brains caused haemorrhage and necrosis of the cerebral hemisphere, which was not followed by significant regeneration of neural tissue. This preliminary study suggests that it cannot be assumed that the fetal brain will regenerate itself after injury, and that this should be considered when making plans for operative procedures on the central nervous system in utero.

Lumbo‐peritoneal Shunting‐a Forgotten Operation?

11. Wada, J . A . (1978) ‘The clinical relevance of kindling: species, brain sites and seizure susceptibility.’ In Livingstone, K. E.. Hornykiewicz. 0. (Eds.) Limbic .Mechanisms. New York: Plenum Press. 12. Crandall, J . E. , Bernstein. J Zornetzer, S. F. (1979) ‘Kind hippocampus: absence of dendritic alterations.’ Behavioral and .Veural Biologj,. 21, 5 14-522. 13. Wada. J. A . (1977) ‘Pharmacological prophylaxis in the kindling model of epilepsy.’ Archivc~s of

Comparison of healing of lesions in the calvarium of foetal lambs and young sheep.

This study compares the healing of lesions made in the occipital region of the calvarium of 5 foetal and 4 post-natal lambs. The foetuses, operated on between the 83rd and 91st day of gestation, had a bone flap elevated and the post-natal lambs, aged about 6 weeks, had a craniectomy and replacement of the bone pieces. The foetuses were delivered spontaneously at full-term. All the animals had computed tomographic (CT) scans and, after sacrifice, naked eye examination of the bony lesions. These showed that there was poor ossification of the lesions made in the foetuses compared to those made in the post-natal lambs. These findings need to be taken into account when intra-uterine correction of cranio-facial deformities are being contemplated.

Effect of early revascularization on the ischaemic rat brain.

Rat brains made regionally ischaemic by manipulation of the large vessels in the neck were revascularized up to 4 hours later. Mortality rates, patterns of ink staining and the water content of the brains were studied. Scanning and transmission electron microscopy was carried out. The results showed that whilst revascularization did not reperfuse areas of the brain that had been subjected to very low levels of perfusion, it did reperfuse other areas with higher perfusion and, in so doing, prevented the extension of the ischaemic process into them.