Blood, bone marrow, thymus, spleen, lymph Flashcards
Proerythroblast
Large cell with a large and intesely stained nucleus
Sparse, thin rim of intensely stained cytoplasm (high content of RNA, lack of Hb)
Normoblast
Cell and nucleus shrunk
almost 100% Hb in cytoplasm
~eosinophilic
final stage befor extrusion of the nucleus
approx same size as RBCs
Myelocyte
Cytoplasm contains both azurophilic (nonspecific) granules and specific granules
basophilic cytoplasm + granules
large, eccentrically placed nucleus with finely dispersed chromatin
Metamyelocyte
Cells decreased in size
nucleus demonstrating signs of indentation
cytoplasm: non-specific and specific granules
Eosinophils
bi-lobed nucleus
Neutrophils
3-5 lobed nucleus
Basophils
Intensely basophilis/numerous granules that obstruct the nucleus
Monocyte
Cytoplasm contains granules but not readily seen
Eccentrically placed nucleus + indentation
Lymphocytes
Large nucleus
Thin rim of pale-staining cytoplasm
Bone marrow
Bone marrow
Bony trabeculae/spicules - pink/pale purple
Adipocytes
In between adipocytes: red bone marrow - purple
Red marrow
megakaryocytes - very large and purple
Lymph node
Capsule/trabeculae
Cortex: superficial cortex - primary/secondary nodules containing B lymphocytes
Paracortex - most T lymphocytes
Medulla: medullary cords + sinuses that contain reticular cells and lymphocytes (B) + macrophages, DCs, plasma cells
High endothelial venules
Lymphocytes enter lymph node via HEV
located in paracortex
lined with cuboidal/columnar epi
specific receptors for lymphocytes to facilitate migration of lymphocytes into lymph node
B and T cells move through by diapedesis
T cells remain in paracortex
B cells migrate to lymph nodules in the superficial cortex
HEV
lymphocyte traversing HEV in lymph node
Reticular tissue with silver stain
reticular fibers - type III collagen secreted by resident stellate reticular cells
reticular cells also coated with migration ligands that facilitate lymphocyte adhesion and migration within the lymph node
Thymus
CT capsule giving rise to trabeculae
extend into the parenchyma, divides thyus into lobules
Supportive framework by epithelioreticular cells
Thymic lobule
Darker peripheral zone - cortex
- densely packed, small immature T cells
- epithelioreticular cells - stellate with pale-staining nuclei
- macrophages most abundant in corticomedullary region
lighter central zone - medulla
- more mature T lymphocytes
- also epithelioreticular cells, dendritic cells, B cells
- T cells less numerous, larger, paler-staining than cortex
- Hassall’s corpuscle (red): specific type of epithelioreticular cells belived to be involved in the removal of dead thymocytes
Blood-thymus barrier
capillary endo + basal lamina
perivascular CT space (has macrophages)
epithelioreticular cells (= thymic nurse cells) + thick basal lamina
prevent exposuer of immature T cells to foreign & self Ag
Epithelioreticular cell on top
Lymphocytes below (3)
Cortex of thymus
Blood-thymic barrier
Macrophage on top
Endothelial cells surrounding lumen
Black arrow on left - epithelioreticular cells (pale: thick basal lamina)
Mature thymus
Involutions (shrinkage) in lymphoid tissue as we age
Under control of several steroid hormones
Gradual replacement of parenchyma by adipose tissue
Loss of cortical tissue/lymphocytes
Atrophic thymus
massive loss of thymocytes
adipose tissue dominates parenchyma
boundary between medulla and cortex indistinct
Spleen
Green - white pulp
- more basophilic because of the lymphocytes - arranged as PALS (T) around the central artey, or as lymphatic nodules (B)
Red - red pulp
- filter that removes foreign material/damaged/old RBCs
- also a storage site for iron, RBC, platelets
- consists of splenic cords + splenic sinuses
- splenic cord = meshwork of reticular cells, fibers and other cells
Spleen
Red: PALS - T lymphocytes surrounding a central artery
Green: central artery
White pulp - primary or secondary B cells, secondary with germinal centres
Spleen bloodflow overview =)
