Fetal Pig Thymus:
* Size: Relatively large and prominent, occupying a significant portion of the chest cavity.
* Structure: Contains numerous lobules, each with a central medulla and outer cortex.
* Function: Primarily involved in the development and maturation of T lymphocytes (T cells) from precursor cells. This process is crucial for the development of a functional immune system.
* Activity: Highly active in producing T cells, contributing to the establishment of the pig's immune system.
Adult Pig Thymus:
* Size: Shrinks significantly in size and becomes less prominent.
* Structure: Lobules may become less distinct, and the thymus tissue can be replaced by fat.
* Function: Continues to produce some T cells, but its activity is significantly reduced compared to the fetal stage. It plays a less active role in the immune system.
* Activity: While still crucial for maintaining some immune function, its overall contribution to the immune system declines.
Key Differences:
* Size and Location: The fetal thymus is significantly larger and occupies more space in the chest compared to the adult thymus.
* Activity: The fetal thymus is highly active in T cell production, whereas the adult thymus is less active and more involved in maintaining existing T cell populations.
* Structure: The fetal thymus has well-defined lobules, while the adult thymus may have less distinct lobules and can contain fatty tissue.
Involution: The process of shrinking and declining activity in the thymus gland as an animal ages is known as involution. This is a natural process and is crucial for the development of a balanced immune system.
In Summary: The fetal pig thymus is a vital organ for the development of the immune system, while the adult pig thymus retains some immune function but plays a less active role. The differences reflect the transition from immune system development to maintenance.