HEMATOPOIESIS [INTRO + MESOBLASTIC PHASE]]

Question 1

This is a continuous, regulated process of blood cell production that includes:
- Cell Renewal
- Proliferation
- Differentiation
- Maturation

A process involved of all various cellular elements of the blood from these stem cells.

Answer 1

Hematopoiesis

Question 2

This is where our RBC, WBC, and Platelets come from.

They are immature cells and cannot function and needs maturation.

This is the* earliest stage* for hematopoiesis.

Answer 2

Hematopoietic Stem Cells

Question 3

This is where our hematopoietic stem cells are produced.

Answer 3

Mesoderm Layer of Germ Cells

Question 4

What are the three layers of the germ cells?

Answer 4

• Mesoderm
• Ectoderm
• Endoderm

Question 5

What are the three developmental periods for hematopoiesis?

Answer 5

• Mesoblastic Phase
• Hepatic Phase
• Myeloid Phase

Question 6

This is the first phase and starts during embryonic development.

Starts at 19th day until 8-12 weeks of gestation.

Cells from the mesoderm migrate to the yolk sac and AGM.

Some of these cells form primitive erythroblasts in central cavity of the yolk sac (blood islands) and other angioblasts.

Hematopoietic activity is confined to erythropoiesis.

Answer 6

Mesoblastic or Mesenchymal Stage

Question 7

In the Mesoblastic Phase, what are the site, onset, and cells produced?

Answer 7

• Site: Blood Islands of the Yolk Sac
• Onset: 19th Day of Gestation
• Cells Produced: Erythroblasts

Question 8

What are the characteristics of erythroblasts produced during the mesoblastic phase?

Answer 8

• Large and megaloblastic.
• Formed intravascularly within the developing blood vessels.
• Retains their nuclei.
• Contains embryonic hemoglobin.

Question 9

These are the two blasts cells produced during the mesoblastic phase.

Answer 9

Erhytroblasts and Angioblasts

Question 10

This blasts cell is a form of endothelium that becomes the blood cells.

Answer 10

Angioblasts

Question 11

What are the three embryonic hemoglobin found in the mesenchymal phase?

Answer 11

Gower 1: 2 Zeta + 2 Epsilon
Gower 2: 2 Alpha + 2 Epsilon
Portlant: 2 Zeta + 2 Gamma

Question 12

What are the two sub-phases in the mesoblastic phase?

Answer 12

• Extraembryonic
• Intramebryonic

Extrambryonic phase lasts longer.

Question 13

In the extramebryonic phase, this gives rice to FLK1+ cells that creates embryonic primitive progenitors and endothelial cells (which gives rise to the blood islands of the yolk sac).

Answer 13

Wave 1

Question 14

These are also called the erythroblasts and functions as an RBC for the embryo.

Answer 14

Primitive Progenitor

Note: Its next goal is to migrate to the endothelium.

Question 15

In the extraembryonic phase, this wave produces ** angioblasts** which later forms into the endothelium.

Answer 15

Wave 2

Question 16

What is the role of the endothelium towards primitive progenitor cells?

Answer 16

Provides nourishment for the primitive progenitor.

Question 17

After forming the hemogenic endothelium, what are the possible lineage maturation?

Answer 17

Can become either primitive erythroblasts or macrophages.

If goes in endothelium hematopoietic transition (EHT), it forms into hematopoietic clusters than can become multipotent cell.

Multipotent cells can become mature RBC, macrophages, and neutrophils.

Question 18

This begins at the aorta-gonad-mesononephros (AGM).

Begins at 4 weeks of gestation or 1-2 days later than does the primitive hematopoiesis.

Answer 18

Intramebryonic

Question 19

This wave has the following process:
- FLK1+
- Endothelium
- Hemogenic Endothelium
- Endothelium Hematopoietic Transition (EHT)
- Hematopoietic Clusters
- Erythrocites, Macrophages, and Mast Cells

The only missing component is the primitive progenitor cells.

Answer 19

Wave 3

Question 20

This is the detachtment of the endothelium, futher becoming a multipotent cell.

Answer 20

Breaking of the Endothelial Junction