Proper fixation is the first thing you should take care of. Testes is a really tough tissues wrapped in many tight and dense layers of tissue. And it's a big tissues, too. Fix intact testes in 10% formaldehyde (10 times of vol) overnight. Cut into small cubes
Comes to my mind: "Davidson's (modified) Fixative....
"Fixation of Testes and Eyes Using a Modified Davidson’s Fluid:
Comparison with Bouin’s Fluid and Conventional Davidson’s Fluid"
JOHN R. LATENDRESSE, ALAN R. WARBRITTION, HENNING JONASSEN, and DIANNE M. CREASY
TOXICOLOGIC PATHOLOGY, vol 30, no 4, pp 524–533, 2002
Copyright C ° 2002 by the Society of Toxicologic Pathology
DOI: 10.1080/01926230290105721
Article Fixation of Testes and Eyes Using a Modified Davidson's Flui...
= [NB: for convenient access to PubMed -Data eliminate the 'x' in https
hxttps://www.ncbi.nlm.nih.gov/pubmed/12187944, Abstract and the pdf accessible via (eliminate prior to copy and paste from the following URL "?url_ver=Z39.88-2003& until the very end of the link):