Accumulation of serous fluid in a sacculated cavity; specifically, such an accumulation in the space of the tunica vaginalistestis, or in a separate pocket along the spermatic cord.
Source: PAC, 2016, 88, 713. 'Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)' on page 765 (https://doi.org/10.1515/pac-2015-1202)