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Figure 27. An islet with mostly typical cellular
components but containing several cells with large
nuclei at the periphery, one cell which appears to
contain mucin (arrow) and several cells with large
foamy cytoplasm (arrowheads). Although the islet is
well delineated, in some areas, the cytoplasm of
some cells seems to penetrate between the acini.
H&E, X 65.
there are a few light cytoplasmic cells in the islet
periphery, similar to the cells of peri-insular
ductules. They apparently derived from peri-insular
ductules and seem to represent islet
precursor cells, which have also been identified in
the pancreas of other mammals 34, 118-126 . Under
specific experimental conditions, their relationship
to the intra-insular ductules (channels) has been
demonstrated 87 in the hamster by Lazarus, in
rabbits by Yolk 127 , and in other species, such as
Chinese hamsters, mice, and rats, by Boquist et
al. 118-121 . The cells occur occasionally as
conglomerates in about 12% of our hamster
colony, irrespective of sex and age 101 . Formation
of minute channels resembling rosettes or
distended ductules (tubules) was observed in 2%
of the female hamsters and 5% of the males (Fig.
27). In older hamsters, conglomerate of ductular
structures resembling micro cystic adenoma were
found in an incidence of 23% in males and 21% in
females (Fig. 28). Also, in older hamsters, a
peculiar cell type with abundant eosinophilic, often
vacuolated cytoplasm can be found around and
within some or many islets. Since similar cell
types have been observed in rats fed a liquid
diet 128 , they seem to represent a modified form of
islet cells, identical to hepatocytes (they will be
described in detail later). The transition of these
24
cells to fat-laden cells (fat cells) was observed in
hamsters 101 , as well as in rats in other studies 128 .
These observations confirm the view that islet
cells possess an unlimited potential to undergo a
variety of meta-plastic changes 128 .
Figure 28. Conglomerate of ductular structures in a
72-week-old male Syrian hamster. Cystic distension
occurs in the intra-insular ductules leading to islet
atrophy in a form of bands. H&E, X 32.
As in other mammals, occasional ganglion cells
can be found within some islets of hamsters (Fig.
29). There is also a rich supply of adrenergic
nerves and norepinephrine within hamster islets,
but in contrast to many mammalian species, there
are no demonstrable amounts of
monoamines 129,130 .
Figure 29. Ganglion-like cell on top and several
nerve fibers (arrows) within the pancreas. Nerve
fibers are also present in the surrounding exocrine
pancreas. Anti-beta tubulin staining. ABC, X 80.
The intimate relationship of islet cells to blood
vessels has been studied by Müller 107 in SGH in