Question

Explain how the bone marrow receives nutrients to survive.

List and explain the function of the cells in the bone marrow stroma.

Track the path of maturation of the T lymphocyte.

List four causes of a hyperplastic marrow.

What would you expect to see on microscopic examination of a stained blood smear if the patient has had a splenectomy and why?

Answer 1

Answers :

Q : Explain how the bone marrow receives nutrients to survive.

Ans : The bone marrow receives nutrients primarily through the nutrient artery and the periosteal capillary. The capillaries join with the venous sinuses as they re-enter the marrow. The sinuses gather into wider collecting sinuses that then open into the central longitudinal vein (central sinus)

Q : List and explain the function of the cells in the bone marrow stroma.

Ans : The bone marrow stroma provides a supportive microenvironment for developing hematopoietic cells. It forms a three-dimensional scaffold for support and adhesion of developing cells. It also facilitates cell–cell interactions by providing essential cytokines to the hematopoietic dividing cells.

Q: Track the path of maturation of the T lymphocyte.

Ans : Precursor T cells leave the bone marrow (where they develop from the committed lymphoid progenitor cell) and enter the thymus through arterioles in the cortex. The thymus is the maturation compartment for T-lymphocytes.   As they travel through the cortex and medulla, the T-lymphocytes interact with epithelial cells and dendritic cells, which provide signals to ensure that T cells recognize foreign antigen, not self-antigen. In addition, the T cells undergo substantial proliferation.  

Q : List four causes of a hyperplastic marrow.

Ans :

1. Acute blood loss causes transient erythrocytosis.
2. Increased proliferation of monoclonal or polyclonal populations of hematopoietic cells, such as leukemia
3. Ineffective hematopoiesis. Example: Vitamin B12 deficiency.
4. Abnormal stimulation or abnormal response to stimulation of stem cells/progenitors from internal or external stimulants.

Q: What would you expect to see on microscopic examination of a stained blood smear if the patient has had a splenectomy and why?

Ans : You would expect to see erythrocyte inclusions such as Howell-Jolly bodies and Pappenheimer bodies and in some cases abnormal erythrocyte shapes. This is because the spleen is responsible for pitting inclusions from RBCs and culling abnormal RBCs. The liver can remove some of these abnormal cells but is not as effective as the spleen in doing so.