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Adipose cells

A fat cell, or adipocyte, is a connective tissue cell that has differentiated and become specialized in the synthesis (manufacture) and storage of fat.

3rd to 6th month

spleen begins to play a role.

2nd - 3rd month of fetal development

The liver becomes the primary site of BC production, and the yolk sac ends it role. Myeloid and lymphoid cells begin to appear in greater numbers. Liver produces a high percentage of erythroid cells.

Macrophage ( primary function)

- Primary functions. Phagocytosis Extruded nuclei of maturing erythrocytes Abnormal cells such as B cells that have not differentiated properly. 2.Secretion of hematopoietic cytokines.

Differentiate primary from secondary lymphoid tissue

- Primary lymphoid tissue are Bone marrow and thymus. T and B cells develop from nonfunctional precursors. Become cells capable of responding to foreign antigens (immunocompetent). - Spleen and lymph nodes are the secondary. Further differentiate and divide in response to antigens.

Macrophage ( secondary function)

-Secondary functions of macrophages. Serve as the center for erythroblastic islands. Provides many colony-stimulating factors. For the development of myeloid lineage cells.

Hematopoietic Compartment

1) Macrophages 2)Granulocytes produced in nests 3)Megakaryocytes

Three major Stroma cell types

1) Macrophages. 2) Reticular cells (fibroblasts) - Located on the surface of the vascular sinuses. 3) Adipocytes - Cells whose cytoplasm is mostly replaced with a single fat vacuole. Control the volume of BM in which active hematopoiesis occurs. Distribution of the red: yellow marrow in these sites is about 1:1.

Bone marrow hyperplasia

An excessive development of normal cells Occurs with all conditions of increased or ineffective hematopoiesis

Blood Cell Egress

Blood cells migrate from bone marrow to the vascular space

Bone marrow

Blood-forming tissue found between the trabeculae of spongy bone. Composed of the vascular and hematopoietic compartment. Consists of yellow and red marrow.

7th month of gestation

Bone marrow becomes primary site of hematopoiesis. Continues as primary source of blood production after birth and during adult life.

Erythroid hyperplasia

Erythroid hyperplasia (Decreased M:E) with increased erythroid production.

Cytokines

Erythropoietic, Interleukins and Colony Stimulating Factors.

When do granulocytoc and megakaryocytic production occurs

Granulocytic and megakaryocytic production first occurs at 3 -5 months of fetal life in the bone marrow. RBC transition to the bone marrow at the end of gestation.

major hematopoietic tissue (organs) starting from the beggining

Hematopoiesis begins in the yolk sac of a human embryo.

1. Define and name the components of hematopoiesis.

Hematopoiesis- Production, development, differentiation and maturation of all blood cells. Hematopoietic components Bone marrow , liver, spleen, lymph nodes, thymus

Lymphocytes -Lymphoid progenitor cells

Leave bone marrow, travel to the thymus. Mature in B lymphocytes.

Newborn to infant

Liver and spleen cease hematopoiesis. Fat cells begin to fill marrow in long bones by age 4.

Stem cells

Lymphoid and non lymphoid.

Marrow cellularity at birth and in adults

Marrow cellularity at birth is ~100% and declines to ~50% in adults.

Alkaline phosphatase positive Cell

Osteoblast Cells

Stroma

Supporting bone marrow tissue for the hematopoietic cells.

Peripheral blood

functional & storage pools.

By age 18-20,

hematopoiesis entirely in sternum, ribs, pelvis, vertebrae, skull. Steady state of cell production & destruction.

Describe the function of erythropoietin in hematopoiesis.

• Erythropoietin (EPO) - In the Cytokine. Hormone produced by the kidneys. Stimulates red cell production and division.

Extramedulary hematopoiesis

•Extramedulary hematopoiesis - Increased demand with hematopoiesis in spleen, liver and other tissues. Blood cell production in hematopoietic tissue other than bone marrow. Occurs in liver and spleen.