[Ultrastructural alterations of the capillaries and venules in the central nervous system of pigs after experimental coli endotoxin shock]

Swine cerebrospinal angiopathy and demyelination and malacia

In 15 pigs affected with cerebrospinal angiopathy accompanied by demyelination and malacia, the main symptoms were diarrhea and subsequent circling, spasms, sudden forward movements, ataxia, and inability to hold the head straight. Escherichia coli was isolated in a pure culture from the small intestine of pigs with diarrhea. The only gross change was a slight increase in cerebrospinal fluid. Histologic examination showed vascular lesions, demyelination, and malacia, most commonly located in the medulla oblongata, pons, and midbrain. The vascular lesions were degenerative and there were necrotic changes of the vessel walls and formation of periodic acid-Schiff positive perivascular eosinophilic droplets. Ultrastructurally, the swollen astrocytes around the vessels had many osmiophilic bodies in their cytoplasm with no limiting membrane. Demyelination and malacia, as well as vascular lesions, were considered to be the characteristic changes of cerebrospinal angiopathy. Our study suggests that E. coli may be a cause of cerebrospinal angiopathy.

Ultrastructural observations on human cerebral capillaries in organ culture

The use of an organotypic-in the strictly literal meaning of the word, nervous tissue culture device has allowed the identification and ultrastructural study of various types of developing capillaries in human cerebellum and olfactory bulb in vitro. Most capillaries were similar to those already described by other authors or by us, in human or animal embryos and fetuses. Large Type I Capillaries. Their luminal diameters were greater than 8 microns. The basement membranes were thin and discontinous. Numerous interendothelial junctions were either plate-like attachments or contained pentalaminar zones. Type II Capillaries. Their lumina were between 2 and 8 microns in diameter. The basement membranes were wider than those of type I capillaries and were sometimes continuous. The interendothelial junctional complexes of type II capillaries included pentalaminar portions. Many simple or complex vascular sprouts (type IV and V capillaries) had small or non-patent lumina. Their basement membranes were absent or very thin and discontinuous. Their interendothelial junctions were similar to those of type I capillaries. Some of the less frequently encountered capillary types seen in developing human nervous tissue were absent in culture. Some pathological features were seen-especially in long-term cultures-in type I and II capillaries containing degenerating blood cells or processes sometimes obviously related to histiocytic cells. They consisted mainly of an accumulation of microfilaments and modifications of the rough endoplasmic reticulum in the endothelial cells. These pathological changes did not modify the main characteristics of the capillaries. The origin of the vascular sprouts, the exact nature of the interendothelial junctions and the significance of the pathological changes are discussed. This model may prove useful for the study of cerebral vasculogenesis, the development of the blood-brain barrier and the physiological or pathological properties of the human brain capillaries in tissue culture.

Cerebrovascular ultrastructural alterations after intra-arterial infusions of ouabain, scilla-glycosides, heparin and histamine

Cardiac glycosides which inhibit Na/K-ATPase (ouabain, scilliroside, scillirosidin) as well as heparin and histamine were infused into a cannulated branch of the middle cerebral artery or by isolated head perfusion in cats and dogs. Ouabain permeating the blood-brain barrier (BBB) caused the same selective swelling of astrocytes and of certain presynaptic elements as after direct application to the brain tissue. The other cellular elements of brain tissue and the vascular endothelium did not react, although the latter was exposed to the highest drug concentrations (about 10-3 M ouabain). By the swelling about one third of the capillaries became more or less constricted accompanied by an increase in endothelial vesiculation and in the number of osmiophilic inclusions in all cells of the vascular wall and of the pericapillary tissue. Osmiophilic material resembling plasma proteins occured in widened intercellular clefts indicating an increased BBB permeability after survival times (40 min). In contrast to the capillaries some terminal vessels are dilated which may correspond to shunt vessels causing an inhomogeneous, even increased cerebral blood flow after ouabain. Scilliroside and scillirosidin cause essentially the same changes as ouabain, but of smaller intensity and extent. In the present study, neither histamine nor heparin caused any structural change of the vessels or brain tissue.