Serous ovarian cystadenocarcinomas account for ~25% of serous tumours. Serous fluid may also originate from mixed glands, which contain both mucous and serous cells. The perimetrium is a serous layer of visceral peritoneum. Cancer in a serous cavity is called a serous carcinoma. This pericardial sac is filled with a serous fluid for lubrication. Roughly 30% of endometrial serous carcinomas also have psammoma bodies. An epididymal cyst is a cyst of the epididymis containing serous liquid. The other major salivary glands produce mixed (serous and mucus) saliva. Salivary glands can be classified as serous, mucous or seromucous (mixed). Nasal corticosteroids may be associated with central serous retinopathy. The secretion of this gland is more serous in dogs and more mucous in bulls. Amphibians possess two types of glands, mucous and granular (serous). Usually there are recognizable clumps of serous cells inside the tumor. He compared this feature to the serous and mucous structures of embryos of higher animals. The tunica vaginalis is the pouch of serous membrane that covers the testes.