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Flashcards in Histo Deck (9)
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1

What is bone marrow?

spongy tissue in the middle (medullary) cavities of bone

red marrow - active bone marrow, full of dividing stem cells and precursors  precursors of mature blood cells, in adults, only some bones are used for this

yellow marrow - inactive bone marrow - dominated by fat cells - may be reactivated (extreme blood loss)

 

adults 50 red : 50 yellow

2

How does one examine bone marrow?

  • bone marrow biopsy (large bore needle - captures bone architecture)
  • fine needle aspirate 
  • typically get both 

3

Describe general features of bone marrow biopsy?

few things to highlight:

  • bony trabeculae around
  • reticular fibers are spider web that support all the cells = meshwork (remember black spider webs from before - not stained here) = fibroblasts
  • meshwork of vascular sinuses (purple dots) - blood cells leave marrow via sinuses (S) - light red dots
  • haemopoietic cells ( red, H)
  • adipocytes (A)
  • about 50% A and 50 H (remember its 50 % red marrow and 50% yelllow marrow in adults )
  • large dot on the bottom is megakaryocyte that will produce platelets

4

What does bone marrow smear look like?

picture attached

RBC like cells are in bone marrow, since this is bone marrow aspirate, these are still immature RBCs - reticulocyte

5

Which cells come from lymphoid lineage?

hemopoietic stem cell -> common lymphoid progenitor or common myeloid progenitor

 

in common lymphoid progenitor:

  • NK cell
  • T cells
  • B cells -> plasma cells

6

Which cells come from myeloid lineage?

hemopoietic stem cell -> common lymphoid progenitor or common myeloid progenitor 

 

common myeloid progenitor ->  granulocyte / monocyte progenitor:

  • dendritic cell
  • neutrophil
  • basophil
  • mast cell
  • eosinophil
  • monocyte -> macrophage

common myeloid progenitor -> megakaryocyte/erythrocyte progenitor:

  • magakaryocyte -> platelet
  • reticulocyte -> erythrocyte (extrusion of nucleus and organelles - reduces in size; goal is to make as much Hb as possible before maturity -> does this by having a lot of ribosomes, etc - > early RBCs stain extremely basophilic - full of proteins! and as cells mature, these ribosomes and other synthesizing parts disappear and cells become eosinophilic)

 

 

7

Describe stages in RBC lineage?

  • PROerythroblast (pale-purlle nucleus, very little and very dark cytoplasm)
  • BASOPHILIC erythroblast: intensely basophilic b/c ribosomes need to synthesize Hb, ribosomes are made of rRNA and RNA stains basophilic
  • POLYCHROMATIC erythroblast (change in colour, both basophilic (some ribosomes remaining) and eosinophilic (b/c Hb is eosinophilic)), greyish cytoplasm
  • NORMOBLAST: more eosinophilic cytoplasm b/c high HB content. very small and dark nucleus (basophilic)
  • RETICULOCYTE: no more nucleus, but still could have some purple dots - has some rRNA remaining (if in bone marrow always reticulocyte b/c not yet matured), if in blood, could be reticulocyte or erythrocyte
  • RETICULOCYTES MATURE IN 2-3 DAYS WHEN RELEASED IN BLOOD
  •  

8

RBC development timelines?

  • 5-7 days for full cycle form proerythroblast to RBC
  • reticulocyte takes 2-3 days in blood to mature to RBC (so at least 1% of all RBCs are normally reticulocytes)
  • normal lifespan about 120 days
  • 1 proerythroblast ~ 32 mature erythroblasts because of mitosis in early stages of maturation (proerythroblast to polychromatic erythroblast ; remember this as normoblast is still "normal" b/c has nucleus but it is condensed and tiny, so no longer reproducing)

9

What is left shift?

Left shift or blood shift is an increase in the number of immature leukocytes in the peripheral blood, particularly neutrophil band cells.

Neutrophil band cell = cell that passed metamyelocyte stage, but is not yet mature neutrophil (hematopoietic stem cell -> common myeloid progenitor -> myelocyte (granulocyte already) -> metamyelocyte (granulocyte with indented nucleus, like horse-shoe, more mature)