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shape with an almost transparent cytoplasm may
be why they escaped the attention of anatomic
histologists. These almost transparent cells
contain oval or spindle-shaped nuclei with a
lesser chromatin content than those of acini (Fig.
12).
Figure 12. Acinar and centroacinar cells (CAC) in
the pancreas of the hamster. Acinar cells have
various number of zymogen granules of different
size and plenty of RER and microvilli on the luminal
surface. In contrast, CAC cells have many
mitochondria (M) and junctional complex (arrows)
but fewer microvilli. TEM X 4,122.
These cells merge imperceptibly into those of
intercalated ductules, which have oval, or flask-shaped,
dentated or convoluted vesicular nuclei
within the scanty, ill defined, light acidophilic
cytoplasm when stained with H&E. The
intercalated ductules (Fig. 13) communicate with
the peri-insular ductules, which often form a circuit
around the islets and into which several
neighboring intercalated ductules enter (Fig. 14).
Figure 13. Intercalated ductal cells with microvilli.
TEM X 3,600.
16
Figure 14. Pancreatic islet after the injection of
India ink into the common duct. a) Left: peri-insular
ductule filled with ink. A small branch (lower left
area) of incoming or outgoing ductule. X80. Right:
Central portion of the islet with areas filled with ink X
120. b) From ink-filled peri-insular ductule, branches
run toward the center of the islet. X 120. c) A perinsular
duct containing ink and a tiny, apparently
independent, ductule in the center. X 80. d) A
section of a peri-insular ductule in an islet. Note the
presence of India ink in the center of the islet
(arrow). X 120.
Figure 15. Several neighboring islets are linked
together by ductules, which surround or go through
the islets. X 80.
Signifying the tight connection between the
exocrine and the endocrine elements is the
attachment of islets to ductular structures that
runs through one islet to another in a remarkable
“rosary beads” fashion (Fig. 15). The cells of the
peri-insular ductules are usually small and hardly
distinguishable from the α-cells in routine
histological sections, which populate the
peripheral zone of islets in this species. From the
peri-insular ductules, fine, branching (intra-insular)
ductules penetrate into the islets (Fig.14b-d) as
has been described in other rodents 102 and in