Hematology 1: Hematopoietic System & Blood Cell Maturation

Vocabulary flashcards covering principles of blood cell maturation, hematopoietic cell lineages, stem cell types, and detailed morphologic characteristics across erythropoiesis, granulopoiesis, monopoiesis, lymphopoiesis, and megakaryopoiesis.

Synchronistic Maturation

The normal maturation process of a blood cell, characterized by orderly and proportional changes in cell size, nucleus, cytoplasm, nuclear chromatin, and cytoplasmic granules.

Euchromatin

Uncondensed, delicate, fine, and linear nuclear chromatin predominant in immature blood cells that stains pale blue.

Heterochromatin

Condensed, coarse, and clumped nuclear chromatin present as a blood cell matures, which exhibits dark staining.

Pelger-Huet Anomaly

A condition associated with nuclear hyposegmentation in granulocytes caused by an abnormality in Lamin B.

Totipotential Stem Cells

The most versatile type of human stem cells present in the first few hours after an ovum is fertilized, capable of developing into any human cell type, including the fetus.

Pluripotential Stem Cells

Human stem cells present several days after fertilization that can differentiate into any cell type except a fetus.

Multipotential Stem Cells

Adult stem cells derived from pluripotent stem cells that are restricted to producing specific cell types to form specialized tissues.

Erythropoietin (EPO)

A lineage-specific glycoprotein primary regulator of erythropoiesis produced in the renal peritubular cells of the kidney in response to oxygen availability.

Pronormoblast

The first recognizable erythroid precursor, measuring $12\text{--}20\,\mu\text{m}$ in diameter with an N:C ratio of $8:1$, 1-2 nucleoli, and dark blue cytoplasm due to high ribosome content.

Basophilic Normoblast

The second stage of erythropoiesis, measuring $10\text{--}15\,\mu\text{m}$ with an N:C ratio of $6:1$, condensing chromatin, and the first detectable hemoglobin synthesis.

Polychromatic Normoblast

An erythroid precursor stage ($10\text{--}12\,\mu\text{m}$, N:C ratio $4:1\text{ to }1:1$) characterized by pinkish-grey cytoplasm due to hemoglobin accumulation; it represents the final stage capable of mitosis.

Orthochromic Normoblast

Also known as a metarubricyte, a non-dividing erythroid stage ($8\text{--}10\,\mu\text{m}$, N:C ratio $1:2$) with a completely condensed pyknotic nucleus and salmon-pink cytoplasm.

Reticulocyte

An anucleated red blood cell precursor ($8\text{--}10\,\mu\text{m}$) containing remnants of RNA, mitochondria, and ribosomes, detectable using supravital stain.

Erythrocyte

A mature, anucleated biconcave disc measuring $6\text{--}8\,\mu\text{m}$ in diameter with a central pallor occupying one-third of the cell, functioning to deliver oxygen to tissues over a span of approximately $120\text{ days}$.

Myeloblast

The earliest recognizable granulocytic precursor ($14\text{--}20\,\mu\text{m}$) comprising $0\%\text{--}3\%$ of nucleated bone marrow cells, featuring an N:C ratio of $4:1$ and 2-5 nucleoli.

Promyelocyte

A granulocytic precursor ($16\text{--}25\,\mu\text{m}$) comprising $1\%\text{--}5\%$ of marrow cells, distinguished by abundant primary (azurophilic) granules and a paranuclear halo (HOF).

Myelocyte

Referred to as the Dawn of Neutrophilia, a granulocytic stage ($12\text{--}18\,\mu\text{m}$) where primary granule production ceases, secondary granules begin to form, and mitosis occurs for the last time.

Metamyelocyte

Also called a juvenile cell, a non-dividing granulocytic stage ($10\text{--}15\,\mu\text{m}$) characterized by an indented, kidney bean-shaped nucleus and the onset of tertiary granule production.

Neutrophil Band

An immature granulocyte ($9\text{--}15\,\mu\text{m}$) featuring a C, S, or Z-shaped nucleus indented greater than half its diameter without actual nuclear segmentation.

Segmented Neutrophil

A mature granulocyte ($9\text{--}15\,\mu\text{m}$) containing lilac-pink granules and a nucleus divided into $2\text{--}5$ lobes connected by threadlike filaments.

Primary (Azurophilic) Granules

Granules produced during the promyelocyte stage that contain enzymes including myeloperoxidase, acid $\beta$-glycerophosphatase, cathepsins, defensins, elastase, and proteinase-3.

Charcot-Leyden Crystal Protein

A specific cytochemical protein present within the primary granules of eosinophil promyelocytes.

Monoblast

The earliest monocytic precursor ($12\text{--}20\,\mu\text{m}$) featuring an N:C ratio of $4:1\text{ to }3:1$, non-granular cytoplasm, fine lacey chromatin, and cytoplasmic blebs (pseudopods) used for locomotion.

Promonocyte

A monocytic precursor stage ($12\text{--}18\,\mu\text{m}$) characterized by a slightly indented or folded nucleus, delicate chromatin, and blue cytoplasm with fine azure granules.

Monocyte

A circulating leukocyte ($15\text{--}20\,\mu\text{m}$) with a deeply indented or horseshoe-shaped nucleus, lacelike chromatin, and blue-gray ground-glass cytoplasm that differentiates into tissue macrophages.

Megakaryoblast

Stage I megakaryocyte precursor ($14\text{--}18\,\mu\text{m}$) featuring an N:C ratio of $3:1$, a round or oval nucleus, and cytoplasm containing small blunt pseudopods.

Promegakaryocyte

Stage II megakaryocyte precursor ($15\text{--}40\,\mu\text{m}$) with an N:C ratio of $4:1\text{ to }7:1$, coarser chromatin, multiple nucleoli, and granule formation initiated in the Golgi region.

Megakaryocyte

Stage III giant bone marrow cell ($30\text{--}50\,\mu\text{m}$) with a multilobed nucleus and low N:C ratio ($< 1:4$), capable of shedding $2000\text{--}4000$ platelets.

Platelet (Thrombocyte)

An anucleated cell fragment ($2\text{--}4\,\mu\text{m}$) derived from megakaryocyte cytoplasm that functions to seal vascular injuries and prevent bleeding.