This is a low-power image of a lobule of the pancreas, on the right side you can
see a bit of connective tissue septa that would divide this lobule from
another lobule. Coming down from the top of the lobule, you can see you can see a
profile of a large artery and a vein and almost at the extreme left of the lobule
you can see a view of islet cells. We'll be looking at the secretory acinar
cells in more detail for this laboratory. On this slightly higher
magnification of the pancreas, you can see a cluster of islet cells on the left
and lots of secretory acini that consists of groups of acinar cells
scattered throughout this lobule and also you can see some profiles of
intercalated ducts. We won't concentrate on the ducts for this laboratory as
we'll get to that later in the course and a still higher power of you, you can
see nice clusters of acinar cells with their basal nuclei and you can get a
sense of the zymogin granules, the secretory granules scattered throughout
the acinar cells. You can also see a couple of profiles of intercalated ducts
one narrow top of the image about at one o'clock and a pair of them at the bottom
of the image. You can see some very small profiles of capillaries and you can also
see some cells that are called centroacinar cells. There's a pair of
centroacinar cells on the left hand side of the image around 9 o'clock. The
centroacinar cells form the smallest divisions of the secretory ducts in the
pancreas and we'll get to these later in the course. Now the zymogen granules are
very evident on this preparation and it's interesting because acinar cells
tend to show a apical acidophilia because of the zymogen granules and more
or less a basal base affiliate because of the rough ER that are synthesizing
the proteins that are in these zymogen granules. Now this this is not so evident
on this preparation but it is very evident on this prep which has been
overexposed photographically just to highlight the basal base of philia
versus the acidic acidophilia. Now the base of philia the
dark blue staining is due to the fact that there's a tremendous amount of rough ER
in these cells which are actively engaged in protein synthesis. The apical
acidophilia is a result of the zymogen granules these are of course the
pancreatic digestive enzymes which are packaged into vesicles and these
vesicles are stored until the cell receives a signal for secretion so the
acinar cell is the prototypical example of a protein secretory cell that
secretes by regulated secretion. This is an H and E stained image point out with
the dark blue, the basal basophilia is through the hematoxylin staining
where the more orange stain is through the eosin staining components of the dye.
Center of the slide is a large profile of an excretory duct from the pancreas
surrounded by connective tissue so really what you're looking at is
connective tissue coming right out at you in the plane of the section with a
lobule on the left side again coming down into the plane of section. This is
actually a view of a plastic section that's prepared for electron microscopy
but the section is viewed with the light microscope. It highlights nicely some of
the basal nuclei in the acinar cells you can clearly see the zymogen granules
up onto the upper right hand side of this image you can see a profile of a
central acinar cell and now the term a gastroplasm is an old-fashioned term
that simply means just rough ER and on the extreme right just above the nucleus
you can see a little bit of a clear area that suggests the Golgi apparatus. In
this electron micrograph of a portion of an acinar cell, you can clearly see
the zymogen granules on the top part of the image and the large amount of rough
ER on the bottom part of this image. On this very low-power electron micrograph
you can see some acinar cells with the basal nuclei you get a hint of rough
ER and then the dark zymogen granules and you can see the direction of the red
arrow the tip of the red arrow is actually in
between acinar cells where the zymogen granules is
secreted into so direction of secretion is in the direction of that red arrow.