Chapter 13. Hematopoiesis

This chapter should help the student to:

• Describe the structural and functional characteristics of a stem cell.
• Compare mature circulating blood cells and hematopoietic stem cells.
• Know the general structural characteristics of hematopoietic tissues and describe the changes that occur in bone marrow composition with age.
• Describe the life cycle of each formed element of blood, from stem cell to death.
• Describe the hormonal control of erythropoiesis and leukopoiesis.
• Name the phases of intrauterine hematopoiesis, the sites where each occurs, and differences in the erythrocytes produced during each phase.
• Recognize the erythrocyte and granulocyte precursors in micrographs of bone marrow. Name the stage immediately preceding and immediately following each cell.

1. Describe pluripotent hematopoietic stem cells (I.A) in terms of:

1. Two names for these cells in scientific nomenclature

2. Embryonic germ layer of origin

3. Degree of differentiation (maturity)

4. Ability to produce a variety of cell types

5. Frequency of cell divisions

2. Name the two types of bone marrow (I.C) and compare them in terms of hematopoietic activity, relative number of adipocytes, the most abundant form in infants and in adults, and sites in the body where they occur in adults (III.A).

3. List the structural components of active bone marrow (other than developing blood cells) in terms of the cell types present (III.A.1), the type of capillaries present (III.A.2), and the type of connective tissue present, including the predominant collagen type (III.A.1).

4. List the functions of active bone marrow other than hematopoiesis (III.A.3).

5. List three organs containing macrophages that actively destroy old red blood cells (III.A.3).

6. Name three by-products of the breakdown of hemoglobin and describe the fate of each (III.A.3).

7. Describe the effects of hypoxia and hemorrhage on yellow bone marrow (I.C).

8. During erythrocyte differentiation and maturation, which general changes (increase, decrease, or no change) are observed in the following:

1. Cell volume and diameter (IV.A)

2. Nuclear volume and diameter (IV.A)

3. Amount of heterochromatin in the nucleus (IV.A)

4. Size and visibility of the nucleoli (IV.B.1 and 2)

5. Number of polyribosomes in the cytoplasm (IV.A)

6. Cytoplasmic basophilia (IV.A)

7. Amount of hemoglobin in the cytoplasm (IV.A)

8. Cytoplasmic acidophilia (IV.A)

9. Number of mitochondria in the cytoplasm (IV.B.5)

9. Beginning with the first recognizable cell type in the erythroid series, list, in order, the six stages of erythrocyte differentiation (IV.B).

10. Return to your list of stages in question 9 and indicate at which stage(s) or between which stages the following events occur:

1. Cells divide (IV.B.1–4)

2. Intense RNA synthesis takes place (IV.B.1 and 2)

3. Cytoplasmic basophilia reaches its peak (IV.B.2 and 3)

4. Hemoglobin synthesis accelerates (IV.B.2)

5. Patches of cytoplasmic acidophilia appear; cytoplasm acquires a grayish tinge (IV.B.3)

6. Hemoglobin synthesis peaks and begins to decline (IV.B.4)

7. Capacity for mitosis is lost (IV.B.4)

8. Nucleus is extruded (IV.B.4)

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