Hematopoiesis Intro & HIM Microanatomy

Question 1

Haematopoeisis refers to the formation of blood cells (RBCs, WBCs, and platelets). It can be further classified into:
_____
______(comprising ____&_____)
_______

Answer 1

1. Erythropoiesis
   2.Leukopoiesis (comprises granulopoiesis and lymphopoiesis)
2. Megakaryopoiesis or thrombopoiesis

Question 2

In embryonic life first ___ weeks of pregnancy, the yolk sac is the site of haematopoiesis.

The developing foetus has blood formed in the yolk sac in what weeks

Answer 2

13

3rd to 4th

Question 3

The process starts in the wall of the yolk sac as early as the ___ day after the coitus that resulted in the pregnancy. At this time, the yolk sac wall contains _______

Answer 3

8th day
Hemangioblasts

Question 4

By the 8th week, the ____ has been established in the foetus, and the yolk sac haemangioblasts tend to move there, which appears to be the major site of haematopoiesis between the _____&____month of intra-uterine life.

Answer 4

Liver

2nd & 6th
Note says 4th week to 4th month and by month 6-7 liver and spleen stop forming blood

Question 5

By the ____ month, the human ____ have been well formed, and cavitations appear to show. These cavities are usually occupied by the ____ ____

Note: for what to what month do all the bones in body produce cells

Answer 5

5th

Bones

Bone marrow

Note: 7th month to 24th month

Question 6

However, in this early stage, only_____& _____ occur in the foetal bone marrow.

Answer 6

granulopoiesis and megakaryopoiesis

Question 7

At _____, the whole of erythropoiesis has been transferred to the bone marrow.

Answer 7

Term

Question 8

The mechanisms that lead to the transfer of sites of haemopoiesis from the yolk sac to the liver and to the bone marrow are unknown. However, there is a hypothesis that the bone marrow cells (osteoblasts and osteoclasts) secrete some cytokines including _______& _______that attract or drive haematopoietic cells towards themselves.

Answer 8

neurokinins and Protein P

Question 9

Approximately 6 billion haematopoietic cells are found/kg body weight/day. Below is the breakdown:
• ___billion thrombocytes/kg/body weight/day
• ___ billion leukocytes/kg/body weight/day]
• ____ billion red blood cells (erythrocytes)/kg/body weight/day

Answer 9

2.5

1

2.5

Question 10

What is the structure of the bone marrow from periosteum inwards

Answer 10

Periosteum> cortex> endosteum> bone marrow space (outer> inner)

Question 11

Blood supply to the bone marrow

Answer 11

Arterial supply is by the nutrient artery

This artery pierces into the bone cortex via the nutrient canal. Once it reaches the bone marrow space/cavity, it becomes the medullary artery. In the bone marrow space, the medullary artery often divides into the ascending and descending medullary branches. These branches move across the bone marrow space to reach the endosteal surface of the opposite side. The branches they give off while running in the bone marrow space are known as transfer or arcuate arteries. The arcuate arteries pierce through the endosteum and cortex, and then become capillaries that run through the Haversian canal. These capillaries are known as Haversian capillaries, and they serve as sources of oxygen delivery to bone cells.

Question 12

Venous drainage

Answer 12

The Haversian capillaries turn back to re-enter the bone marrow space and then balloon out to become the bone marrow sinusoids, which drain into the medullary veins. The medullary veins leave the bone marrow as emissary veins.

Question 13

Haemopoiesis occurs within the bone marrow ______

Answer 13

Sinusoids

Question 14

Newly formed cells in the HIM pierce through it to join the circulation. They move from the HIM to enter the _____ veins

Answer 14

Medullary then emissary veins

Question 15

The outer surface of the HIM, which is lined by ________ cells is known as the _____ surface,

Answer 15

Endothelial cells

Luminal surface

Question 16

while the inner surface is known as the _____ surface & is lined by:

Answer 16

Abluminal surface

• Reticulum cells / Adventitial
• Narrow stroma cells
• Some Fibroblasts
• Adipocytes
• Macrophages

Question 17

Reticulum cells secrete ____

Answer 17

Reticulate fibers

Question 18

Fibroblasts and ______ produce _______

Answer 18

Stroma cells

Collagen

Question 19

What types of collagen are produced by stroma cells & fibroblasts

Answer 19

Type 1,3&4

Question 20

Which cells synthesize cement tissue and what are the cement tissue called

Answer 20

All cells of the abluminal surface

glucose AMINOGLYCANS

Question 21

4 Examples of the aminoglycans are

Answer 21

Hyalironic acid
Heparan Sulfate
Chondroitin 4 sulfate
Demartan sulfate

Question 22

A liminal cells also secrete hematopoietic growth factors which are

Answer 22

Granulocyte colony stimulating factor GCSF

Granulocyte Macrophage colony stimulating factor
GMCSF

Question 23

Other proteins that help keep immature cells in the HIM are

Answer 23

Vitrinectin
Hemonectin
Fibronectin

Laminin
Tenancin
Endoglin

Question 24

Some amino acid sequences that are capable of interacting with the early differentiation proteins exhibited by immature haemopoietic cells are found in the reticulin and collagen fibres. An example of early differentiation protein is?

Answer 24

CD7

Stromal proteins are made up of reticulin and collagen fibres. The early differentiation antigens react with the amino acid sequences of reticulin and collagen fibres. This is known as stromal cell interaction.

Question 25

In organization of haemopoeisis within HIM,
Where do these occur?
Erythropoiesis
Thrombopoiesis
Granulocytopoiesis
Lymphopoiesis

Answer 25

1. In close juxtaposition to abluminal cells
2. Same as above
3. Occurs inner to the location of the first 2
4. Very center of HIM