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Blood Test 101: Understanding Red Cell Development

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Published on March 11, 2015

More often than not, patients struggle to understand what the complex acronyms, numbers and symbols mean when blood work is returned. Patient Power Contributor, Dr. Susan Leclair breaks down what acronyms like MCV, and others mean. As a laboratory scientist for over 40 years, she makes educating patients a priority as they battle a serious illness.



Transcript | Blood Test 101: Understanding Red Cell Development

Please remember the opinions expressed on Patient Power are not necessarily the views of our sponsors, contributors, partners or Patient Power. Our discussions are not a substitute for seeking medical advice or care from your own doctor. That’s how you’ll get care that’s most appropriate for you.

Dr. Leclair:

Hello again.  This is Susan Leclair from the Department of Medical Laboratory Science at UMass Dartmouth. And I want to spend a little bit of time today talking about red cells, where they come from, how they're developed, and a little bit about their lifespan if we have the time for that. 

Red cells come from your bone marrow.  They are in the active part of the marrow, which means the part where you've got a lot of blood cells that are busy undergoing mitotic division and growing up and interacting with each other.  They start off as that unidentifiable cell that everybody knows as the pluripotential stem cell so no pictures because no one actually knows what they really look like.  But eventually through a series of mitotic divisions and maturations they become recognizable as developing red cells. 

The first picture is going to show you the earliest recognizable red cell called the pronormoblast, and it's going to look unlike any red cell you've ever seen, because it's not red and it has a nucleus.  Think of this cell as the beginning of a manufacturing process where all the raw materials are coming into one side of the manufacturing plant, but nothing yet has really been made.  So what you have here is a big cell with a nucleus that's very active and very busy transcribing directions and instructions. And you've got a cytoplasm that's bringing in stuff like iron and proteins, because the cell knows it's going to make hemoglobin. 

After a period of time, that cell then undergoes a mitotic division, so now we have two cells and a different name and a slightly different look.  This one is going to show you, yes, it's still blue, yes, it still has a nucleus, but the nucleus is smaller. And you're beginning to see small amounts of hemoglobin being made. 

They're little teeny, tiny patches of pink in an otherwise blue cytoplasm, and that cell now is starting to make hemoglobin.  Typically, about 10 percent of the hemoglobin you need is in that cell. 

Another period of time, another mitotic division, another slide shows you a cell that's now got a fair amount of hemoglobin.  It's got a mixture in the cytoplasm of pink, that's the hemoglobin, and blue, that's the scaffolding, the rough endoplasmic reticulum, the RNA, the assembly line of the manufacturing plant that's making this hemoglobin.  That cell is called a polychromatophilic normoblast.  Poly means many, chromatophilic means likes many colors, so this is a multicolored kind of cell. But the dominant you'll notice is a mixture of the blue and the pink. 

Couple more mitotic divisions, a little more maturation, and now you get to a cell called the orthochromic normoblast, srtho, true, chromic, color.  You notice that it's mostly pink.  It's actually got about 70 percent of all of the hemoglobin that it needs in order to become a functional red cell, so it's not yet ready to get outside into the bloodstream.  It's not yet quite ready for prime time in that sense, but it's really well along its way to finally completing what it's supposed to do. 

At this point in the orthochromic normoblast history, it has something it doesn't need anymore.  It's got that nucleus.  No red cell out in the peripheral blood is supposed to have a nucleus in it, so how do I get rid of it?  And it's really quite amazing. 

This cell actually causes some of its organelles to get on one side of the cytoplasm and just walk across the cell, pushing the nucleus in front of it.  You'll see in this particular picture that the nucleus is broken up into a whole bunch of little pieces that are going to get pushed out of the cell, but in this next one you see the whole nucleus just getting pinched off and pushed out of the cell. 

Once you get that, you have the non?nucleated cell that we all kind of recognize.  Now, this one's still not totally and completely functional.  It's got some blue to it.  It's not yet fully hemoglobinized.  We call it a reticulocyte because when we stain it, like you see in this picture, you’re going to see that it's got a blue network of strands and lumps in it that's called reticulum in the red cell, and it's actually a good thing to have because it's finishing up the last bits of hemoglobin. 

So think of yourself now if you're touring a plant that's manufacturing something, maybe like hemoglobin in what we're looking at but maybe like beer if you're thinking about something else, then you're almost at the point where the beer is ready to be sold.  It's been made, it's got to be packaged, it's got to be pasteurized, it's got to have all its labels put on it, but essentially the product is done. 

This retic stays for about 24 hours in the bone marrow, then it moves out into the peripheral blood as a peripheral blood reticulocyte where it moves around, functions as a red cell, but now has to get rid of all of that RNA and blue stuff it doesn't need anymore, and this is where your spleen comes into the picture.  The red cells go into the spleen, and the splenic macrophages, the white cells that line the blood vessels of the spleen reach down, pick up these three?dimensional things that are in this red cell and pull them out, in the process changing this from a flat disk to the bi?concave shape that you see here.

This cell is your red cell.  This cell should be fully functional with all its hemoglobin and all of its enzymes and its membrane being correct and should last for 120 days, mostly, more or less, maybe 115.  But most people just automatically think 120 days. 

So what happens after 120 days?  As these red cells go through your system they deal with your life.  They deal with changes in pH when they're in your GI tract or when they're in your kidneys.  They change with hot and cold.  They change with oxygen levels.  Are you sleeping?  Are you running? 

They change with the presence of lactic acid buildup in the system, so they're constantly being assaulted by your daily life.  As you assault these cells, a little bit of the membrane gets lost here, another little bit gets lost there, some of the enzymes die off, maybe some of the hemoglobin becomes precipitated, because it's no longer functional.  And what you end up with in that 120?odd days is a cell that's round.  It's kind of hard.  It doesn't really work as well as it should, kind of like this picture here. 

You can see that it's lost some of its membrane and that it's—it just looks hard, and it looks round.  Well, take that round cell and try and push it through a very small capillary.  The smallest capillaries you have are in your spleen. So as the cell gets into the spleen, it gets trapped in the spleen.  We'll have a moment of quiet here because then it dies.  It's given you everything that it could for 120 days, and it gets trapped in your spleen and dies. 

And we'll take up what happens after that next.  Remember, you pay attention to a lot of the stuff that Patient Power's got, because knowledge is your best medicine.  Talk to you next time 

Please remember the opinions expressed on Patient Power are not necessarily the views of our sponsors, contributors, partners or Patient Power. Our discussions are not a substitute for seeking medical advice or care from your own doctor. That’s how you’ll get care that’s most appropriate for you.

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