Figures 1 and 2 are taken from the H&E staining of our
main sample under the magnifications of 4X and 40X respectively. Figures 3 and
4 show the results of the PAS staining of the tissue sample at the same
magnifications of 4X and 40X respectively. Looking at the images, we see that
the tissue contains open channel like spaces separating the groups of cells from
each other. The staining’s show that the cell type most commonly found in this
tissue sample are acinar cells. The PAS staining method, which helps visualize
carbohydrate containing compounds seen in figures 3 and 4, especially the
higher magnification reveals that there are small concentrations of carb
containing compounds in the cells and also in the channels between them.

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Figure 5 is taken from the H staining of another
group’s tissue sample under the magnifications of 4X. There is no 40X image as
the image was actually of the PAS stain. Figures 6 and 7 show the results of
the PAS staining of the other groups sample at 4X and 40X respectively. By
observing these images we can see that the cells in this tissue sample are
separated by sinusoids. There is also the presence of larger round openings
which seem to be veins or ducts. The PAS staining images are also fairly dark
when viewed, which would indicate that there is a high carbohydrate
concentration in this organ or high concentration of carbohydrate containing compounds.


During the course of this Histology lab, we have learned to
do two different cell staining techniques currently used in research studies
today, H&E and PAS. This has allowed us to visualize the different
components of the cells in the tissue such as the nucleus, cytoplasm, and any
carbohydrate containing molecule. This has allowed us to have a better idea of
the types of tissues we are dealing with in our samples and have procedural
knowledge that will help us later on in our lab careers. When looking at the
results of our main tissue sample, the identification of acinar cells in groups
being separated by channel like passages has led me to believe that the sample
observed is from that of a mouse pancreas. When looking at the results of the
other groups tissue sample, the identification of sinusoids, separating columns
of cells, funnelling into a larger opening, has led me to believe that the
second sample is that of a mouse liver.

I believe the first sample to be that of a mouse pancreas
due to many reasons. The first is the identification of the acinar cell type
seen in figures 2 and 4, usually seen in organs with an exocrine function. This
reduces the number of possible organs this sample can be from. When we look at
the literature of Longnecker, we see that the figures obtained in the lab are
very similar to the ones shown in his paper. The H&E staining, figures 1
and 2, of the acinar cells were similar with the nuclei of the cells being more
preferentially situated at the edges of the cells. The second is that the cells
of the tissue in the literature and our figures also make groups, and are
separated by small channels, which connect to the larger channels in the
sample. PAS staining revealed little specks of carbs or carb containing
molecules in the cells and the passages. This could be some of the sugars left
in the cells after the preparation steps of the sample as sugar is known to
travel to the pancreas. These traits point towards the tissue sample being from
a mouse pancreas. The identification of an islets of Langerhans would have made
this decision definite as they are only found in the pancreas.

I believe the sample obtained from the other group is that
of a mouse liver. The first clue that led me to this decision is the identification
of portal vein and a central venule in the low magnification images of the
sample. The central venule can be clearly seen in the high magnification image
of the sample in figure 7. This is clear as there are cells emanating from it
in rows, separated by small channels. When we look at the literature of
Roberston et al., we can see that these structures located in the tissue sample
are called sinusoids, and the rows of cells are hepatocytes. The portal vein
seen in figure 6 can also be clearly seen with what looks like the bile duct
and the hepatic artery located inside as well. When looking at the PAS stained
samples of tissue, we can see that the images are fairly dark when compared to
any of the other images obtained in this lab. This would indicate that this
tissue sample had a high concentration of carbohydrates or carb containing
molecules. This further solidifies my assumption that this sample is from a
liver, as the organ is responsible for the storage and break down of glycogen,
which is a glucose analogue. These traits are what would normally be seen in a
liver, and point this sample in that direction. This classification also makes
it easier to classify the first sample as a pancreas, as it was an exocrine
organ, and not many large organs have exocrine function other than the pancreas
and liver.

Our execution of these techniques were most likely faulty in
one way or another due many errors. The main source of error for our lab was
probably human error. We take time to move, and these techniques require proper
time management while inside these staining solutions. This leads to the
samples either spending not enough time submerged in the current solution or
too much time. This can cause the staining of the cell to be abnormal,
obscuring your ability to visualize your tissue samples under the microscope.
Also one of the steps required the submersion of the sample slide in Eosin Y
for a few seconds, which was probably different for every group. Some of the
difficulties of preparing a histological slide is the handling of the tissue
sample on the slide, as they are not covered, they can easily be removed from
the slide, or parts of the sample could be lost due to incorrectly followed
instruction, which can lead to your sample looking different from what it
should. Other techniques that could have been used are immunohistochemistry and
antibody binding (3). Immunohistochemistry is the use of an antibody attached
to a detection method that when bound to its specific target can be used to
determine the targets location or relative amount. This can be used in
histological analysis’ to find specific target locations in tissue samples such
as the islets of Langerhans in the pancreas, or specific regions of the lymph


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