Focal
ischemia in the cerebral cortex has an effect on the neurohypophysis
I. Ultrastructural changes in capillary vessels of the neurohypophysis
after focal ischemia of the cerebral cortex
by
Malgorzata Frontczak-Baniewicz
Keywords:
capillary vessels; neurohypophysis;
photochemical reaction
Submitted:
February 14, 2001
Accepted: March 16, 2001
Abstract:
OBJECTIVES:
In our investigations we have reported that photochemical
reaction leading to brain ischemia can also be precipitated
with visible light from a non-coherent light source. It was
revealed that focal cerebral ischemia after photochemical
reaction cause the alterations in the capillaries ultrastructure
and perivascular spaces of the barrier-competent regions of
the brain. The purpose of this study is to first characterize
the ultrastructural morphological consequences of photochemically
induced ischemia in the cerebral cortex on the capillaries
of neurohypophysis as the barrier-free region of the brain.
METHOD: We used a model of ischemic brain damage due to obliteration
of microvessels following the photochemical reaction. Rats
were treated with an intravenous injection of rose bengal
and irradiated from a halogen lamp source through an intact
cranium to precipitate microvascular damage. Material for
electron microscopic studies were sampled from the neurohypophysis
1 and 4 days after irradiation (4 animals in each group) in
experimental group and 1 and 4 days after a rose bengal injection
in control group.
RESULTS: Investigations in transmission electron microscopy
revealed platelet aggregation on the endothelium preceded
by its early ultrastructural damage. In the capillaries of
the neurohypophysis, one and four days after irradiation,
numerous microthrombi adhering to the damaged endothelium
were present. The capillary vessels contained a continuous,
rather than a fenestrated endothelium. The basement membrane
was thickened, blurred and locally multiplicated.
CONCLUSION: Our results show that experimentally-induced thrombosis
of cortical microvessels leads to alterations in the capillaries
of neurohypophysis.
