Fig. 1

Density of vessels decreased with age in all examined hippocampal regions (CA1 and CA3 regions and dentate gyrus) of Wistar and OXYS rats (a) with a more significant age-related decrease in OXYS rats: total blood vessel density in the hippocampus was lower in OXYS rats compared to Wistar rats starting from 5 months of age. ^#differences with previous age, p < 0.05; *differences with age-matched Wistar rats, p < 0.05. b Density of blood vessels in the CA1 region of the hippocampus of Wistar and OXYS rats decreased with age. Magnification ×20. The arrows indicate blood vessels. The electron micrographs (c–j) show structural organization of the vessels of 20-day-old and 5- and 18-month-old Wistar and OXYS rats. c A morphologically unchanged vessel with an erythrocyte (Er) in the lumen. En: the cytoplasm of an endotheliocyte. d A morphologically unchanged vessel. N: the nucleus of an astrocyte (Ast). e A morphologically unchanged vessel. N: a nucleus of the endotheliocyte; Ast: the processes of an astrocyte. f The arrowheads indicate an increase in electronic density of the basal membrane of the endotheliocyte. Ast: the process of an astrocyte. g The destructively altered mitochondria (Mit) in the cytoplasm of an endotheliocyte (indicated by the arrow). h Large vesicles in the cytoplasm of an endotheliocyte (indicated by arrows). Massively swollen mitochondria and expansion of the Golgi complex cisterns (indicated by arrowheads). i The arrowheads indicate thickening and folding of the basement membrane of an endotheliocyte. N: the nucleus of the pericyte. j The arrowhead indicates osmiophilic conglomerates in the cytoplasm of an endotheliocyte