MHS 304 Red Bone Marrow

Red Bone Marrow

Red bone marrow tissue sections reveal a densely packed, highly cellular environment supported by a delicate framework of reticular connective tissue. This high cellular density makes the identification of individual cell types challenging in routine H&E-stained preparations.

• Hematopoietic Cells:
  • Developing blood cells in various stages of maturation that are difficult to identify
  • Erythroid Precursors (developing red blood cells):
    • Clusters of cells with progressively smaller, dense nuclei and increasingly pink/red cytoplasm as they mature
    • Large numbers of late-stage red blood cells without nuclei
  • Myeloid Precursors (developing white blood cells):
    • Distinctive nuclei vary from large, round nuclei in immature forms to the segmented or band-shaped nuclei of maturing neutrophils () Toggle Label Visibility
• Megakaryocytes:
  • Most easily identifiable cells (#1,#2,#3) due to their enormous size (50-100 um diameter)
  • Polyploid cells with distinctive, large multilobulated nuclei
  • Responsible for platelet formation through cytoplasmic fragmentation
• Adipocytes:
  • Scattered adipose cells appear as clear, unstained circular spaces where lipid has been dissolved during tissue processing
  • Flattened, peripherally located nuclei (#1 () Toggle Label Visibility ; #2 () Toggle Label Visibility are seen in the rim of adipose cells
• Sinusoidal Capillaries:
  • Thin-walled vessels that form an extensive network throughout the marrow
  • Sinusoids have a discontinuous endothelium that allows mature blood cells to enter the circulation

For detailed examination and precise identification of developing blood cells, bone marrow aspirate smears are preferred, as they allow individual cells to spread in a monolayer for optimal visualization of cellular morphology.

Courtesy of Ronald W. Dudek, Department of Anatomy and Cell Biology, Broady School of Medicine, East Carolina University School of Medicine, Greenville, NC).