Week 6: Hematology, Hematopoiesis, and Lymphoid Lab Flashcards
How can reticulocytes be identified versus mature erythrocytes versus platelets?
They have remnants of RNA (stain blue with H&E) and have a larger diameter than mature erythrocytes. Both lack a nucleus. Platelets are much smaller than the other components of blood.
How can leukocytes be distinguished?
Lymphocytes have very large, rounded nuclei (form B and T cells, antibodies) - agranulocytes
Monocytes are also very large, have large, kidney-shaped nuclei - agranulocytes
Neutrophils have MOST lobulated nuclei and stain salmon-colored - granulocytes
Eosinophils have lobulated nuclei and stain orange-purple - granulocytes
Basophils have lobulated nuclei and stain blue - granulocytes
What is a common way to identify neutrophils?
They have a salmon-pink staining under certain conditions, and have Barr bodies as well (arrow), which are inactivated X chromosomes (indicate a female patient)
How can we identify eosinophils from their granules, other than by coloration?
They have crystals that kill pathogens and parasites in their granules, which can be seen under a TEM
How can you identify basophils from TEM and LM?
Basophils exhibit large granules that partially obscure the lobulated nucleus.
How do you distinguish basophils from mast cells?
The mast cells are mostly in connective tissue, whereas basophils are mainly found in blood
How can you distinguish lymphocytes?
Agranulocytic with round/oval nuclei that fill most of the cytoplasm
How can we identify monocytes? What key word do we look for to make sure we’re looking at monocytes and NOT metamyelocytes, which have similarly-shaped nuclei?
Monocytes are large and agranulocytic, with kidney bean-shaped nuclei. The key word we would look for to distinguish between monocytes and metamyelocytes is “normal” blood, which tells us that the cells have matured.
How do you remember the steps of erythropoiesis, and what are the cells?
Pretty Boys Play Nice Round Everyone
Proerythroblast, Basophilic erythroblast, Polychromatic erythroblast, Normoblast (orthochromatic erythroblast), Reticulocyte, Erythrocyte
How can you tell the difference between basophilic and polychromatic erythroblasts?
Basophilic erythroblasts have a checkerboard nucleus and a darker-stained cytoplasm
Polychromatic erythroblasts have a multicolored nucleus, a lighter-staining nucleus and more condensed chromatin
How do we remember the stages of granulopoesis? What is the stage of granulopoiesis that has ONLY non-specific granules? Which has the horseshoe-shaped nucleus?
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(Myeloblast) Promyelocyte, Myelocyte, Metamyelocyte, Band cell, Granulocyte (segment)
The promyelocyte has non-specific granules ONLY. The band cell has the horseshoe-shaped nucleus.
What are the first stages of granulopoiesis to acquire specific granules?
Myelocytes, including basophilic, neutrophilic, and eosinophilic
How do you identify metamyelocytes versus myelocytes?
They have a kidney-bean shaped nucleus (different) and specific granules (similar in color to myelocyte colors)
What are the primary organs of the lymphatic system?
The thymus and bone marrow
What are the secondary organs of the lymphatic system?
Tonsils, lymph nodes, spleen, Peyer’s patches, vermiform appendix and lymph nodes
What are the key structures of tonsils?
Palatine tonsils are incompletely encapsulated (cap at the epithelial side, no cap at the surface), they have crypts to allow material in for “sampling,” and have stratified squamous non-keratinized epithelium at the surface
What are Peyer’s patches and where are they located?
They are surveillance cells in the ileum and are transient lymphoid nodules. They sample GI material and present it as APCs to B and T cells of the immune system.
What kinds of nodules are present in the appendix?
There are primary and secondary lymphoid nodules present in the submucosa of the appendix. Right side of “T” in photo is a primary nodule (no germinal center) whereas the one on the left is a secondary nodule (germinal center).
What are the main structures of the thymus?
They are encapsulated with multiple nodules, each with a cortex and a medulla. The medulla has white “spots” due to Hassall’s corpuscles (reticular epithelium that has been degraded)
What are the principal structures of the lymph nodes?
The encapsulated lymph nodes contain a cortex (B cells), paracortex (T cells and high endothelial vessels, HEVs, unique to lymph nodes–allow mature lymphocytes to squeeze through cuboidal cells to deliver APC material to developing cells), and the medulla (B cells)
What kind of fibers are in lymph nodes, what are they composed of and what do they do?
Reticular fibers made of Type III collagen (connective tissue) form a loose scaffold through which lymphatic fluid can flow. This allows antigens to come into contact with lymphocytes.
What are the two main tissue types within the spleen?
White pulp (WBCs) contains central arterioles (CA) with surrounding T cells, germinal centers, and marginal zone (MZ) sinuses that allow T cells to recognize antigens in blood and develop based off of the antigens recognized. The PALS (PeriArteriolar Lymphatic Sheath) surrounds the CAs with T cells. Blood flows out into the MZ (mostly B cells), then back to the CA.
Red pulp (RBCs) contain sinusoids surrounded by reticular fibers. These filter aged erythrocytes, which are phagocytosed by macrophages during passage through slits in the sinusoids.
Where are the B and T cells of the spleen mostly found?
T cells are found in the PALS (PeriArteriolar Lymphatic Sheath) surrounding the central arterioles.
B cells are found almost everywhere else in the white pulp, including the marginal zones and germinal centers
