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.

In a Japanese male, the left testicular artery originated from the aorta as high as 1 cm cranial to the origin of the left inferior phrenic artery. The testicular artery emitted two branches, one to the costal part of the diaphragm and the other to the suprarenal gland. This testicular artery is the most highly positioned one that has ever been reported.

Frog erythrocytes injected into the pleural cavity of mice reached the pericardial cavity. Pericardial pores that connect the two cavities were the routes of the migration. As soon as 5 minutes after injection, frog erythrocytes were surrounded and phagocytosed by attached macrophages in milky spots facing the pericardial cavity. The pericardial pores may function in an allied self-defense mechanism between the pleural and pericardial cavities in this species.

An oncocytoma of the upper eyelid that occurred in an 82-year-old male was studied immunohistologically according to the avidin-biotin-peroxidase complex method (secretory component, carbohydrate antigen 19–9, carcinoembryonic antigen, anticytokeratin AE1/AE3, S–100 protein, myoglobin, actin, vimentin). The staining properties of columnar-type oncocytes were the same as those of epithelial cells of excretory ducts µ of Moll’s gland, but those of polygonal-type oncocytes were similar to those of myoepithelial cells of Moll’s gland. Our results suggested that excretory duct epithelial cells of Moll’s gland are the origin of oncocytoma of the eyelid.

Oncocytoma rarely arises from the eyelid and only 2 cases have been reported previously. We present a case of oncocytoma in the upper eyelid around the lacrimal punctum. Anatomical location and histological findings suggested that oncocytes of this tumor originated from the epithelium of Moll’s gland or the lacrimal canaliculus.