Spumiform basement membrane aberrations in the microvasculature of the midbrain periaqueductal gray region in hamster: Rostro-caudal pathogenesis?

► Spumiform capillary basement membrane degeneration (sbmd) is a specific form BM aberration. ► Sbmd occurs with extremely high densities in the periaqueductal gray (PAG) region. ► Severe stages of sbmd were more frequently observed at the intermediate PAG levels. ► At the rostral and caudal PAG less severe sbmd stages were more prominently present. ► The various forms of sbmd in the PAG of senescent hamsters is a general 'PAG-phenomenon'.