Cervical thymuses exist, but no cervical thymomas develop in thoracic thymoma-prone BUF rats

Area of Science:

• Immunology
• Oncology
• Rat Genetics

Background:

• The thymus, crucial for immune function, is typically located in the chest.
• The presence and function of a cervical thymus, located in the neck, are not well understood.
• Certain rat strains, like BUF/Mna (BUF), are prone to developing thymoma.

Purpose of the Study:

• To investigate the existence of the cervical thymus in rats.
• To determine if cervical thymuses can develop thymoma, particularly in thymoma-prone strains.
• To compare the behavior of cervical and thoracic thymuses in spontaneous thymomagenesis.

Main Methods:

• Examined cervical and thoracic tissues from inbred (BUF, ACI, WKY) and congenic rat strains.
• Tissues were fixed, sectioned, stained with hematoxylin and eosin, and examined microscopically.
• Congenic strains involved transferring genetic regions related to nude (Rnu), thymus enlargement (Ten1, Ten2), thymoma susceptibility (Tsr1), muscle atrophy (Aftm1), and proteinuria (Pur1) into BUF, ACI, or WKY rats.

Main Results:

• Cervical thymuses were detected in 12-21% of rats across various strains.
• No cervical thymuses were found in athymic BUF-Rnu/Rnu rats.
• While thoracic thymomas developed in BUF and ACI-Tsr1/Tsr1 rats, no cervical thymomas were observed.

Conclusions:

• Cervical thymuses are present in a subset of rats and their development is linked to the absence of the nude (Rnu) gene.
• Cervical thymuses do not appear to undergo spontaneous thymomagenesis.
• Cervical thymuses exhibit different behavior compared to thoracic thymuses regarding spontaneous thymoma development.