Topic 23 - Prenatal and potential hematopoiesis, structure of the bone marrow, heamatopoietic stem cells

Question 1

what is hematopoiesis?

Answer 1

formation of blood cellular components

Question 2

Prenatal hematopoiesis

where and how does it begin?

Answer 2

• Blood cell generation begins in the wall of the yolk sac during intrauterine life. Primitive erythroblasts derive from mesenchyme.
• hp cells then migrate to the liver

Question 3

Prenatal hematopoiesis

where are the hp cells delivered?

Answer 3

• delivered to the bone marrow, spleen, lympnodes and thymus of the embryo
• begin hp

Question 4

Postnatal hematopoiesis

-where does it occure?

Answer 4

-occurs in the bone marrow, but also in liver and spleen a few weeks after birth

Question 5

Postnatal hematopoiesis

-Red bone marrow is present in?

Answer 5

sternum,vertebrae, ribs, skull, pelvis and epiphysisis of long bones

Question 6

Postnatal hematopoiesis

what happens as demand for blood cells decreas with age?

Answer 6

active red bone marrow is replanced bu yellob bone marrow

Question 7

Bone Marrow

Answer 7

• Soft flexible connective tissue within bone cavities
• Lacks lymphatic vessels
• Two types: red and yellow
• Vascular and non-vascular sections (where hematopoiesis occures)

Question 8

Strucutre

Hematopoietic compartment conist of?

Answer 8

irregular anastomosing (tubular) cords lying between vascular sinuses. Blood cells are produced within the hematopoietic compartment before crossing the wall of the vascular sinuses.

Question 9

strucutre

they are supplied(innervated) by?

Answer 9

vasomotor nerves surrounded the blood vessel

Question 10

strucutre

advential reticular cells?

Answer 10

meshwork that supports hp cells and provides special microenvironment influencing stem cell development. Can be filled with fat and develop into adipose cells when hematopoiesis decreases

Question 11

strucutre

marrow hematopoiesis

Answer 11

is most activeein areas close to the bone

Question 12

strucutre

What cells are close to vascular sinuses?

Answer 12

Erythropoietic cells and megakaryocytes

Question 13

structure

what cells are fare away from the vascular sinuses

Answer 13

pranulopoietic cells

Question 14

Hematopoietic stem cells

szice

Answer 14

undifferentiated
are typically larger than differentiated cells, due to a large euchromatic nuclei. Therefore stem cells decrease in size as they mature.

Question 15

Hematopoietic stem cells are………….?

and what does that mean?

Answer 15

PLURIPOTENT
capable of giving rise to several different cell types.
As a pluripotent cell type, a human embryonic stem cell is capable of forming all adult cell types.

Question 16

Where do we find stem cells?

Answer 16

embryonic yolk sac, fetal liver, spleen, and bone marrow

Question 17

What can primitive stem cells give rise to?

Answer 17

-the mulitpotent myeloid stem cells:
(unipotent: erythrocytes, granulocytes, monocytes, and megakaryocytes) or
-the unipotent lymphoid stem cells
(lymphocyte, myloid)

Question 18

Myeloid stem cells:

Lymphoid stem cells:

Answer 18

hematopoietic stem cell becomes myeloid progenitor.

hematopoietic stem cell becomes lymphoid progenitor.

Question 19

Marrow hematopoiesis – active in areas close to bone, cells are arranged depending on fuction:

Answer 19

• Erythropoietic cells and megakaryocytes – near vascular sinuses.
• Granulopoietiuc cells – deep within the cords, away from vascular sinuses.