Histology Flashcards
Erythrocyte diameter and lifespan:
Diameter: 7 micrometers
Lifespan: 120 days
Neutrophil diameter and frequency:
Diameter: 12 micrometer
Frequency: 60-70% of WBCs
What cell is shown in this slide?
This is a neutrophil (note the characteristic multi-lobed nucleus)
What cell type is shown in this slide?
Eosinophil
What is the diameter and frequency of an eosinophil?
Diameter: 12 micrometer
Frequency: 2-4% of WBCs
What is the diameter and frequency of a basophil?
Diameter: 10 micrometer,
Frequency: 0.5 - 1% of WBCs
What cell is shown in this slide?
Basophil
What is the diameter and frequency of lymphocytes?
Diameter: 10 micrometers,
Frequency: 20-25% of WBCs
What is shown in this slide?
Lymphocyte
What is the diameter and frequency of monocytes?
Diameter: 15 micrometers,
Frequency: 3-8% of WBCs
What cell is shown in this image?
Monocytes
What is the diamater of a platelet?
3 micrometers
Describe the stages of erythropoieses:
Erythropoieses is the process of RBC maturation/production. Cells get smaller and pinker on slides as they mature. There are 6 main steps:
- Proerythroblast,
- Basophilic erythroblast,
- Polychromatic erythroblast,
- Orthochromatophilic erythroblast,
- Reticulocyte,
- Erythrocyte
Describe basophilic erythroblasts:
Moderately sized, strongly basophilic cells. These are the first cells to look for on a slide.
Describe polychromatophilic erythroblasts:
These are the third stage of erythropoiesis. These are cells with increasing acidopilia and pyknotic nuclei (condensing chromatin during apoptosis).
Describe orthochromatophilic erythroblasts:
These are the fourth step of erythropoiesis. These are smaller nucleated cells with cytoplasm that is close to the color of mature erythrocytes (pinker). Very short-lived.
Describe reticulocytes:
These are the final stage of development before mature RBC. While reticulocytes are found in both bone marrow and peripheral blood, they are difficult to identify without stains such as cresyl blue.
Describe the process of granulopoiesis:
Granulopoiesis is the process of granulocyte (neutrophil, eosinophil, and basophil) maturation. Stages:
- myeloblast,
- promyelocyte,
- myelocyte,
- metamyelocyte,
- stab cell,
- mature cell (e.g. neutrophil)
Describe promyelocytes:
Promyelocytes are large cells with conspicuous azurophilic granules.
Describe myelocyte cells:
Myelocytes show specific granules, a nucleus that is slightly flattened or indented, and a hint of a Golgi region.
Describe metamyelocytes:
Metamyelocytes show a sharply indented nucleus in a V or U shape and a lightly stained Golgi region; the nucleus is frequently obscured by the distinctive granules in developing eosinophils and basophils (whereas developing neutrophils do not have these)
Describe band, or stab, cells:
Stab cells have a horseshoe shaped nucleus
What is the function of this cell?
This is a neutrophil - it phagocytoses, kills, and digests bacteria
What are azurophilic and specific granules?
Azurophilic granules are lysosomes (very small) containing various hydrolytic enzymes. “Specific granules” (which make a granulocyte a granulocyte) are very small and hard to see in the neutrophil, but they are present; these specific granules contain various enzymes and other molecules in the neutrophil.
This cell represents ____% of all leukocytes:
This is a lymphocyte; 20-25% of WBCs
Do lymphocytes have azurophilic granules or specific granules?
These cells are agranulocytes, so they contain no “specific granules.” They do, however, contain some azurophilic granules, which are lysosomes (very small) containing various hydrolytic enzymes.
This cell becomes a ______ in connective tissue:
This is a monocyte - becomes a MACROPHAGE in connective tissue
Do monocytes contain specific or azurophilic granules?
These cells are agranulocytes, so they contain no “specific granules.” They do, however, contain many azurophilic granules, which are lysosomes (very small) containing various hydrolytic enzymes.
This cell represents ___% of all leukocytes:
This is a basophil; represents 0.5-1% of leukocytes
Do basophils contain specific or azurophilic granules?
Azurophilic granules are lysosomes (very small) containing various hydrolytic enzymes. “Specific granules” (which make a granulocyte a granulocyte) are very large and dark blue/black in the basophil; specific granules contain various factors including histamine in the basophil.
What is the function of these cells?
These are eosinophils; defend against helminthic infections
Do eosinophils have specific or azurophilic granules?
Azurophilic granules are lysosomes (very small) containing various hydrolytic enzymes. “Specific granules” (which make a granulocyte a granulocyte) are very large and dark pink in the eosinophil; specific granules contain various enzymes in the eosinophil.
What is the structure marked by the letter D?
A drumstick appendage (D) is an appendage of the nucleus that represents the inactive heterochromatic X chromosome seen in 3% of the neutrophils of females. It is also known as a Barr body.
Put these 8 stages in order from earliest to latest.
Put these 4 stages in order:
(Granulocytic series - neutrophil)
- UNC (promyelocyte),
- Duke (myelocyte),
- Wake Forest (metamyelocyte),
- ECU (stab cell)
Prenatal hematopoiesis occurs in the yolk sac, then ____, then ____, and finally ____.
Prenatal hematopoiesis occurs in the yolk sac, then LIVER, then SPLEEN, and finally BONE MARROW.
Which cells in the erythropoietic series undergo mitosis?
Proerythroblasts, basophilic erythroblasts, and polychromatophilic erythroblasts undergo mitosis, whereas orthochromatophilic erythroblasts and reticulocytes have ceased mitosis. Some sources indicate that polychromatophilic erythroblasts can no longer divide, as well.
Where can this cell be found?
This is a reticulocyte. It is found in both the red marrow and peripheral blood.
Which cells in the granulocytic series undergo mitosis?
Myeloblasts, promyelocytes, and myelocytes undergo mitosis, but metamyelocytes and stab (band) cells do not.
What do these cells give rise to?
Thse are megakaryocytes. They give rise to PLATELETS.
What is shown in this slide?
This is an image of the thymus. The lighter spots are medulla, and the darker regions are cortex.
T cells move from the cortex to the Medulla as they Mature.
Blood-thymus barrier:
- Capillary endothelium and basal lamina
- Perivascular connective tissue (e.g., macrophages)
- Thymic epithelial “reticular” cells and basal lamina
What is shown in this slide?
This is an image from the medulla of the Thymus. The pink circular regions are Hassall’s corpuscles, and the darker regions around that contain mature T cells.
What is shown in this slide?
This is an image of the GALT in the cecum. The GALT area contains mostly B cells.
What is shown in this slide?
This is an image of the GALT in the ileum. The triangle of lighter cells is the Peyer’s Patch, which contains activated B cells. The dark area in front is called the Mantle. This contains resting B cells, and Microfold (M) cells are located at the top of the triangle. These are APCs.
What is shown in this image?
This is an image from the tonsil. The tonsils have a dense collection of nodular lymphoid tissue, which contain activated B cells. Also noteworthy is the crypt (meant to trap food and other particles and present to resting B cells) and the M cells.
What is shown in this slide?
This is a lymph node.
Cortex: has nodules on outer edge containing B cells
Paracortex: contains densely packed T cells.
Medulla: contains a combination of B and T cells, as well as macrophages, plasma cells, etc.
What is shown in this slide?
This is a slide taken from the cortex of a lymph node.
Can see the afferent lymphatic vessel where lymph comes in through, and the subcapsular sinus, where the lymph flows through inside the node. See the lymphoid nodule containing active B cells. (When infected with something, you have much more active B cells and these nodules swell, causing palpable swelling of the nodes on the body).
What is shown in this slide?
This is a slide of the paracortex (the thymus-dependent region). T cells are label. In the center is the high-endothelial venule, which is a blood supply for the lymph node, providing oxygenation as well as a new supply of B and T cells.
What is shown in this slide?
This is an image of the medulla of the lymph node.
Have medullary sinus with macrophages and lymphocytes, and medullary cords which have APCs, macrophages, B and T cells. This is the final place where the lymph fluid is traveling through the lymph node. From the sinus, it’s a short distance to the large efferent lymphatic vessel, and the lymph has traveled through the whole node. Can see a collection of B and T cells traveling through this efferent lymphatic vessel.
What is shown in this slide?
This is an image of the spleen. Can see white pulp (region with B and T lymphocytes) and red pulp (region of red blood cell destruction).
What is shown in this slide?
This is an image showing the red and white pulp of the spleen. The white pulp has specialized areas for the B and T cells. (T cells are near the periarteolar sheath - PALS). The red pulp contains splenic cords alternating with splenic sinusoids.
What is shown in this slide?
This is an image from the spleen, showing the white pulp and red pulp. The center is the Germinal Center, which contains B cells. The Mantle Zone is next, followed by the marginal zone. Around this is the red pulp.
The marginal zone is a sinusoidal region between the red and white pulps at the periphery of the PALS. It receives blood from capillary loops derived from the central artery and thus is the first site where blood contacts the splenic parenchyma. It is richly supplied by macrophages and other APCs. Finally, it is the region where circulating T cells and B cells enter the spleen before becoming segregated to their specific locations within the organ and where interdigitating dendritic cells are able to display their MHC-epitope complex for recognition by T cells.
What cells are contained within the yellow circle?
T cells that are becoming immunocompetent
(they are located in the cortex of the thymus
The cells within the yellow circle originated in _____ and will preferentially migrate to _____
Bone marrow; paracortex of lymph nodes.
This is the medulla of the thymus. T cells originate in the bone marrow, migrate to the thymus for maturation, and then migrate to a secondary lymphoid organ like the paracortex of a lymph node.
The cells within the yellow circle originate in ______ and become immunocompetent in ______.
bone marrow; bone marrow
What is the main cell type in the region at the yellow arrows?
B lymphocytes
Which area is thymus-dependent in this lymph node?
2 - the paracortex.
The paracortex is composed of a nonnodular arrangement of mostly T cells. This is also the region where circulating lymphocytes gain access to lymph nodes via high-endothelial (post-capillary) venules.
In this lymph node, region A contains _____ whereas region B contains _____
B cells; T cells.
In this lymph node, what is the structure at the yellow arrow?
afferent lymphatic vessel
A lymph node is a small, encapsulated ovoid to kidney-shaped structure with a capsule that sends trabeculae into the substance of the node. The convex surface of a lymph node receives afferent lymphatic vessels, whereas the concave surface (the hilum) is the site where arterioles enter and venules and efferent lymphatic vessels exit.
What is the structure at the question mark?
efferent lymphatic vessel
The medulla lies deep to the paracortex and cortex, except at the region of the hilum. It is composed of medullary sinusoids (lighter areas) and medullary cords (darker areas). Medullary sinusoids are endothelium-lined spaces supported by reticular fibers and reticular cells. They frequently contain macrophages. Medullary sinusoids receive lymph from the cortical sinuses. Medullary cords are composed of lymphocytes and plasma cells. This region (at the hilum) is the site where arterioles enter and venules and efferent lymphatic vessels exit. Seen here is an efferent lymphatic vessel.
In this image from a lymph node, in which region are B cells maturing and proliferating?
A - region A contains B cells that are maturing and proliferating.
Region B, the mantle, contains resting B cells.
What is found at A and B in this image of the spleen?
A is the red pulp - is composed of sinusoids supported by a loose type of connective tissue (splenic cords / cords of Bilroth). Sinusoids are lined by fusiform endothelial cells separated by relatively large blood-containing intercellular spaces and have a discontinuous basal lamina underlying the endothelium and circumferentially arranged ribs of reticular fibrils. Splenic cords (cords of Billroth) contain plasma cells, stellate reticular cells, blood cells, and macrophages enmeshed within the spaces of the reticular fiber network. Processes of the macrophages enter the lumina of the sinusoids through the spaces between the endothelial cells.
Region B contains the white pulp, with B and T cells
In the image of the spleen, what is the structure at the arrow?
central arteriole
In this image of the spleen, what cells are found at the region at the arrows?
T cells.
This is the periarterial lymphatic sheath (PALS) composed of T cells and surrounding central arterioles.
