This document discusses the primary lymphoid organs - the thymus, bursa of Fabricius, and bone marrow. The thymus and bursa are the major sites of lymphopoiesis where lymphocytes mature. The thymus is located in the chest and brings about cell-mediated immunity and graft rejection. The bursa is found in birds and is the training center for B lymphocytes. Bone marrow is located within cavities of bones and serves as the "army headquarters" where red blood cells, white blood cells, and platelets are produced. It also generates lymphocytes and plays a role in lymphatic fluid circulation.

1. Name: A.JENIFA
III BSC Zoology

2. DEFINITION:
The organs concerned with The
Production of immune cells and
immune reaction are called
lymphoid organs.
× Primary lymphoid organs.
× Secondary lymphoid organs.
2.Types

3. PRIMARY LYMPHOID ORGANS
Major Of lymphopoiesis*.
Prodution centres & Army head
Quarters of the immune system.
Largeat birth and theyatrophywithage.
..
.

4. THYMUS OF
MAN

5. THYMUS OF CHICKEN
* The bird is made up of 7 lobes.
* Thymus is covered by fibrous capsule.
* Organized into lobules.
* Separated from one another by septa
called trabeculae.

7.  Medulla consists of vascular structure, reticular
Epithelial cells & scattered lymphocytes.
 T lymphocytes mature in the thymus.
 It brings about cell mediated immunity.
 It bring about graft rejection.

8. Thymectomy
 Surgical removal of thymus.
 Removed from mice soon after birth.
 Suffered from hunched appearance, ruffled
fur and diarrhoea.

9. oPrimary lymphoid organ in birds.
oTraining centreforthearmyofB lymphocytes.
o Cells present in yolk sac, liver and bone marrow.
o Bursa is a sac- like lymphoepithelial structure.
o Outer cortex and an inner medulla.

10.  Primary lymphoid organ.
 Soft tissus located with in the cavities bones.
 It is the Army head Quarter.
 Red marrow.
 Yellow marrow.
 stroma.
Types

11. 1.Red marrow:
Medulla ossium rubra.
Consists of mainly haematopoietic.
Cantains blood vessels and capillaries.
2.Yellow marrow:
Medulla ossium flava.
Found interior of long bones .
Cantains blood vessels and capillaries.
3.Stroma :
Provides a haematopoietic micro environment.
Generates colony stimulating factors .
Provides iron for RBC.

12. Bone Marrow Barrier
Inhibit the immature blood cells from leaving the maroow.
Lymphatic Role
 Generate lymphatic cells .
 It is primary lymphoid organ.
 Back flow of lymphatic fluid into the bone marrow.
Disease of bone marrow
 Malignancial.
 Anaemia.
 Tuberculosis.
 Leukemia.

13. Bone Marrow Examinations
 Bone marrow biopsy.
 Bone marrow aspiration.
 Early humans ate bone marrow of bones left by lions .
 Vietnam beef bone marrow is used as soup.
Functions of bone Marrow
 Malignancial.
 Anaemia.
 Tuberculosis.
 Leukemia.
Bone Marrow Food