ULTRASTRUCTURAL CHANGES OF BBB CAUSED BY BRAIN METASTASIS AND HUMAN GLIOMA

Objective This study aimed to observe the ultrastructural changes of blood-brain-barrier(BBB)caused by brain metastatic tumor and glioma and probe into their meaning.Methods Ten samples of brain metastasis and 10 samples of human gliomas were observed by transmission electron microscope,especially on ultrastructural changes of BBB in tumor tissues.All samples were obtained from tumor resection by operations at the Second Hospital of Hebei Medical University from 2004 to 2005.Results Ultrastructural changes of brain metastasis BBB were as follows:①Tight junctions were enlarged obviously;②Typical fenestrations were found;③Neoplastic cells were seen out of vessel.Ultrastructural changes of astrocytomas BBB included:①The amount of pinocytosis vesicle increased;②Local thickened basment membrane layering and clipping with pericytes were observed;③The number of gelatinous mebrane reduced;④The tight junctions were intact.Compared with low-grade astrocytomas,BBB of high-grade astrocytomas was broken more severely.Cavitations were found in the basement membrane and extracellular matrix increased.Conclusion Changes of brain metastasis BBB may provide a possible blood route metastasis for brain metastatic tumor.BBB of brain metastatic tumor lost integrity due to deficiency of gelatinous membrane.Compared with brain metastasis,these findings may be as one of the reasons for high invasion and low metastasis in human gliomas.