Non-sprouting angiogenesis in neurohypophysis after traumatic injury of the cerebral cortex. Electron-microscopic studies.

OBJECTIVES: Angiogenesis comprises two different mechanisms: endothelial sprouting and intussusceptive microvascular growth. The sprouting process is based on endothelial cell migration, proliferation and tube formation. Intussusceptive microvascular growth divides existing vessel lumens by formation and insertion of endothelial columns into the vessel lumen. The morphological features of microvessels of cerebral cortex and neurohypophysis were evaluated in a model of the cerebral traumatic injury.

METHOD: The observations were conducted seven days after induction of cortical trauma. Traumatic injury was induced in the fronto-temporal region of cerebral cortex in general anesthesia with 20mg/kg ketamine hydrochloride.

RESULTS: Seven days after traumatic brain injury in sections from cerebral cortex and neurohypophysis we can observe morphological features of angiogenesis. Endothelium of the cerebral cortex possesses high endotheliocytes tightly connected and enveloped by amorphous basement membrane-like material. Transcapillary pillars tightly connected with neighbouring endothelial cells split the newly formed vessels and branching takes place. In neurohypophysis we can observe all stages of non-sprouting angiogenesis: proliferation endothelial cells on the inside mother vessel, splitting newly formed blood vessels by transcapillary pillars directed into the vessel lumen, maturation of endothelium and network formation.

CONCLUSION: The mechanical injuries directly induced angiogenesis not only in cerebral cortex, but also in neurohypophysis. Our studies show that mechanism of angiogenesis is not the same as observed previously in neurohypophysis after focal cerebral ischemia (Neuroendocrinology Letters 2001; 22:87 92). This study indicates that mechanism of angiogenesis can depend on kind of induction.