The melanomacrophages in a spleen of a common carp.

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Naphthalene
Posts: 124
Joined: Sun Mar 29, 2015 7:34 am
Location: Moscow, Russia

The melanomacrophages in a spleen of a common carp.

#1 Post by Naphthalene » Sun Mar 29, 2015 3:43 pm

The spleen of carp is an immune and blood-producing organ. It filters the blood from foreign substances and generates red and white blood cells. This organ is usually considered non-edible and thus the big fish is not only a dish, but also a plenty of material for microscopic studies :D
I have prepared the histological sections of carp spleen. The spleen fragments were fixed in neutral-buffered formalin. The tissue was processed through series of alcohols, cleared in xylene and embedded in paraffin. The sections were cut at 6 micron thickness using rotary microtome with a non-disposable knife.
The first image demonstrates hematoxylin and eosin stained section, where the overall spleen morphology can be seen. The tissue is dense and consists of multiple cell types including oval erythrocytes and irregularly shaped mesenchymal cells. The brown and orange spots in the cells are not due to some artifact in fixation or staining, these are the natural pigments: brown-colored melanin, and orange lipofuscin and hemosiderin. The pigments are produced by special cell type of fish immune system – the melanomacrophages. Individual melanomacrophages contain varying amounts of pigmented substances. Upon ageing, the melanomacrophages aggregate and form dark-colored centers in fish spleen.
The abovementioned pigments appear to have a strong auto fluorescence that can be seen using blue and green excitation filters. The nuclei were counterstained with blue DNA stain DAPI, and sections were then imaged using a fluorescent microscope.

The low-mag view was made using 5X objective. The pigmented islands of melanomacrophages can be seen.

The higher-mag view was produced from 40X objective. I have also made a close-up view of a melanomacrophage center.

I dont know why the image order is reversed, Every next image appears before the previous one. I have the higher res images, dear Oliver, if you would allow I would send them to your email.
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CC spleen 5x all in one small.jpg
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gekko
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Re: The melanomacrophages in a spleen of a common carp.

#2 Post by gekko » Sun Mar 29, 2015 8:31 pm

Naphthalene, it is great that you have joined the new forum! I for one have missed your posts. As usual, excellent sections and images, and a lot of exacting preparatory work involving a great deal of effort! And beautiful, sharp autofluorescence images. To your knowledge, do other animals' spleens also contain pigments that fluoresce?

Naphthalene
Posts: 124
Joined: Sun Mar 29, 2015 7:34 am
Location: Moscow, Russia

Re: The melanomacrophages in a spleen of a common carp.

#3 Post by Naphthalene » Mon Mar 30, 2015 10:22 am

gekko wrote:Naphthalene, it is great that you have joined the new forum! I for one have missed your posts. As usual, excellent sections and images, and a lot of exacting preparatory work involving a great deal of effort! And beautiful, sharp autofluorescence images. To your knowledge, do other animals' spleens also contain pigments that fluoresce?
Hello, Gekko! Thank you, I'm glad to see you again too! I have missed your kindhearted replies and your massive experience in the microimaging/photography! :)

As for the fluorescent pigments in spleen of other animals, I actually know very little about them. EDIT: From what I have red, I believe that melanomacrophages are unique to the fish. I think that similiar pigmented macrophages may be present in lower vertebrates (Ilamprey and hagfish), and maybe in frogs*. In the mammals the accumulation of pigments in spleen cells might appear in a consequence of a disease or ageing and some dark-coated animals have melanocytes (another pigment-bearing cells, responsible for skin colour) not only in the skin, but also in their spleen.

* I hope to study that once I would have the proper samples. Since I cannot catch these myself I'm thinking about purchasing a specimen from a biology supply house, like Blades biological. I wonder if these specimen are suitable for histological studies...

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gekko
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Joined: Sun Oct 12, 2014 7:38 am
Location: Durham, NC, USA.

Re: The melanomacrophages in a spleen of a common carp.

#4 Post by gekko » Mon Mar 30, 2015 1:35 pm

Naphthalene: you are too kind. Many thanks for your reply. I hope we will see more images of beautiful sections!

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