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Pericardium of rodents: pores connect the pericardial and pleural cavities
T Nakatani1, H Shinohara, Y Fukuo
1Department of Anatomy I, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Japan.
Abstract:
Numerous circular fenestrations or pores were present in the pericardium of the rat, golden hamster, and mouse. The pericardial pores were most numerous in the mouse. They were usually less than 50 micron in diameter and situated in a meshwork formed by thick, wavy bundles of collagen fibers and thin, straight, elastic fibers. These pores directly connected the pericardial and pleural cavities and indirectly connected the right and left pleural cavities; i.e., the pericardial cavity in the rodents is not independent from but intercommunicates with the adjacent pleural cavities. There were many aggregates of free cells or milky spots in the pericardium. They principally consisted of lymphocytes, macrophages, and mast cells and were directly exposed to the pericardial cavity.
Insights
Rodents possess pericardial pores connecting the pericardial and pleural cavities, allowing communication between these spaces. These pores, most common in mice, facilitate intercavity fluid and cell movement.
Area of Science:
- Comparative anatomy
- Histology
- Mammalian physiology
Background:
- The pericardium, a serous membrane, encloses the heart.
- The independence of the pericardial cavity from adjacent pleural cavities is a key anatomical consideration.
Purpose of the Study:
- To investigate the presence and characteristics of fenestrations within the pericardium of rodents.
- To determine the functional implications of these pericardial pores on cavity intercommunication.
Main Methods:
- Microscopic examination of pericardial tissue from rats, golden hamsters, and mice.
- Histological analysis to identify and characterize pericardial fenestrations and associated cellular structures.
Main Results:
- Numerous circular fenestrations (pores) were observed in the pericardium of rats, golden hamsters, and mice, with the highest density in mice.
- These pores, typically under 50 microns, are embedded in a collagen and elastic fiber meshwork.
- Pericardial pores directly link the pericardial and pleural cavities, enabling intercommunication.
Conclusions:
- The rodent pericardium is not an independent cavity but intercommunicates with pleural cavities via fenestrations.
- These findings reveal a previously underappreciated pathway for fluid and cellular exchange between the pericardial and pleural spaces in these species.