Histology: Blood Cells & Hematopoiesis

What is the average lifespan of a mature erythrocyte in human circulation?

Approximately 120 days.

Which type of white blood cell is the most numerous in a healthy adult peripheral blood smear?

Neutrophils, typically making up 50-70% of the total white blood cell count.

From which large, multinucleated bone marrow cell are platelets derived?

Megakaryocytes.

In a healthy adult, what is the primary anatomical site for active hematopoiesis?

Red bone marrow, primarily located in the axial skeleton (e.g., pelvis, sternum, vertebrae).

Describe the characteristic nuclear morphology of a mature neutrophil.

A multi-lobed nucleus, typically containing 3 to 5 lobes connected by thin chromatin threads.

Which leukocyte is characterized by large, brick-red/orange acidophilic granules and is primarily involved in fighting parasitic infections?

Eosinophils.

Which blood cell contains dark purple or blue granules that often obscure the nucleus and contain heparin and histamine?

Basophils.

What is the primary role of monocytes once they exit the bloodstream and enter peripheral tissues?

They differentiate into macrophages to perform phagocytosis and act as antigen-presenting cells.

What does an elevated reticulocyte count typically indicate regarding bone marrow activity?

Increased erythropoiesis, usually as a compensatory response to blood loss or hemolysis.

How do spherocytes appear on a peripheral smear, and what do they lack compared to normal RBCs?

They appear small, dark, and perfectly spherical, lacking the central pallor of normal biconcave erythrocytes.