3.14 Microanatomy of Thymus, Bone Marrow, Lymph Node and Spleen Flashcards
Type of immune system:
- Diffuse lymphatic tissue
- Peripheral organs
- Organized lymphatic tissue
Diffuse lymphatic tissue examples:
-GI tract
-respiratory system
-skin
-MAlT
Peripheral organs examples:
-appendages
-payers patches
Organized lymphatic tissue examples:
-lymph node
-spleen
-thymus
Cells of immune system:
-reticular fibers: support structural organization, on outside
-lymphocytes: fixed cells
Types of lymphocytes:
-T-cells
-B-cells
-NK cells
Prenatal blood formation:
-0-3 months: yolk sac
-1-9 months: liver
-3-6 months: spleen (little)
-4-9 months: bone marrow
Primary lymphoid organs:
-thymus
-bone marrow
Thymus:
-ventral to trachea and esophagus
-important in young animal (regresses at puberty)
>lots of T-lymphocytes and wane as it degenrates
-cortex and a medulla
Thymus medulla:
-some left over epithelial cells that produce keratin
>involved in selecting maturing lymphocytes: thymic corpuscles
Blood-thymus barrier:
-limits what is exposed to developing lymphocytes so can have a specific antigen response
Thymus-immunological function:
-selection of cells
-cortex to medulla
-90% of cells get cleared
Why do we need secondary lymphatic organs?
-respond to infections
-percolators located at strategic locations
Lymph nodes: most domestics
-afferent vessels on curved side
>nodules in cortex (more outside)
-efferent vessel ‘inside’ of curve
Lymph nodes: pigs
-“inside out”
-afferent vessels ‘inside of curve’
-efferent vessels on curved side
-nodules more in center
