Liver
The comparative histopathological characteristics of age-related changes
in the liver in the studied groups of rats are presented in Table 3. In
liver sections of the control group of young male rats, all animals had
liver architecture corresponding to the histological norm. With
hematoxylin and eosin staining, the liver consisted of numerous hepatic
lobules formed by cords of hepatocytes radiating outward from the
central vein to the lobule periphery, separated by sinusoids (Table 3).
Hepatocytes had a polygonal shape with eosinophilic granular cytoplasm
and vesicular-basophilic nuclei. Masson’s trichrome staining showed
collagen fibers in the walls of the portal tract vessels but absent in
the extracellular matrix (Table 3). Histochemical staining (PAS)
revealed glycogen in the form of violet-purple fragments in the
cytoplasm of most hepatocytes in all animals (Figure 9).
Animals in the old untreated group, showed evidence of age-related
changes with hematoxylin and eosin staining including; hepatocyte
vacuolization, inflammatory/immune changes with lymphocyte and plasma
cell infiltration (Figure 9 or Table 3). Hepatic sections of all animals
in the group were characterized by microvesicular vacuolization of
hepatocyte cytoplasm (Table 3). Two out of three animals in the group,
displayed some hepatocytes contained nuclei of various shapes and sizes,
and binucleated hepatocytes in some fields (Figure 9). No signs of
central venous congestion were observed in any animal in the group.
Portal tracts in all three animals of the group were characterized by
dilated and congested portal veins and hyperplasia (cysts) of bile
ducts, and an increase in the number of lymphocytes and plasmacytic
cells infiltrating between hepatocytes in the portal areas was observed
(Table 3). Masson’s trichrome staining showed proliferation of collagen
fibers in the portal tracts with individual thick and long collagen
fibers in the extracellular matrix of all animals (Table 3).
Histochemical staining (PAS) showed that most hepatocytes were
PAS-negative or contained a few scattered glycogen granules of
violet-purple color in less than 10% of hepatocytes in all rats (Figure
9).
However, focal microvesicular vacuolization of hepatocytes and focal
lymphocytic infiltration were observed in all animals in the exosome
only group. Cellular pleomorphism, part of hepatocytes contained nuclei
of variable size and shape, as well as binucleated hepatocytes and
hyperplasia (cysts) of bile ducts observed in two of the animals in the
group (Table 3). Masson’s trichrome staining in all animals showed
perioportal proliferation of collagen fibers (Table 3). Histochemical
staining (PAS) showed that most hepatocytes were PAS-negative or
contained a small amount of glycogen of violet-purple color, and in one
animal glycogen was present in less than 61% of hepatocytes (Table 3)
and (Figure 9).
Interestingly, all animals in the group that was treated with quercetin
loaded exosomes exhibited focal microvesicular vacuolization of
hepatocytes, focal lymphocytic infiltration, and hyperplasia or cysts of
bile ducts (Table 3). Two of the animals showed abnormalities in nuclear
size and chromatin distribution, and binucleated hepatocytes. Masson’s
trichrome staining in all animals showed perioportal proliferation of
collagen fibers (Table 3). Histochemical staining (PAS) in histological
liver sections of two animals revealed glycogen in less than 10% of
hepatocytes, and in one case – in 11-30% of hepatocytes (Table 3).
While two of the animals that received free quercetin, exhibited focal
microvesicular vacuolization of hepatocytes, binucleated hepatocytes,
lymphoplasmacytic infiltration, and hyperplasia (cysts) of bile ducts,
all of animals exhibited perioportal fibrosis (Table 3). Glycogen in all
animals was detected in less than 10% of hepatocytes (Table 3).