Organs (Part 2 - Bursa of Fabricius)

Bursa of Fabricius

Found only in Birds/ Avian species

Bursa of Fabricius

Round sac located above the cloaca

above the cloaca

Bursa of Fabricius: Round sac located —

Bursa of Fabricius

Reaches the greatest size- 1-2 weeks after hatching & then shrinks as the bird ages

1-2 weeks after hatching

Bursa of Fabricius: Reaches the greatest size- — & then shrinks as the bird ages

shrinks ; ages

Reaches the greatest size- 1-2 weeks after hatching & then — as the bird —

epithelial tissue

Lymphocytes embedded in —

Bursa of Fabricius

lines a hollow sac connected to the cloaca by a duct.

Lymphoid follicles

— divided into a cortex and medulla

cortex and medulla

Lymphoid follicles- divided into a —

cortex

— Lymphocytes, plasma cells andmacrophages

Lymphocytes, plasma cells and macrophages

Cortex:

medullary epithelial cells

— replaced lymphoblasts and lymphocytes

lymphoblasts and lymphocytes

Medullary epithelial cells- replaced —

Bursa of Fabricius

Maturation and differentiation site for the cells of the antibody-forming system.

Bursa of Fabricius

Acts like thymus- migrating cells from bone marrow to the bursa

bone marrow

Acts like thymus- migrating cells from — to thebursa

Bursa of Fabricius

90 to 95%- dies by apoptosis

apoptosis

90 to 95%- dies by —

Surviving B cells

— migrate to secondary lymphoid organs

secondary lymphoid organs

Surviving B cells migrate to

Bursa of Fabricius

Not a pure primary lymphoid organ

Bursa of Fabricius

Can also trap antigens and undertake some antibody synthesis

Bursa of Fabricius

Contains Bursin- activates B cells and not T cells

bursin

Contains — : activates B cells and not T cells

B cells

Contains Bursin- activates — and not T cells