Noun, pl. gubernacula
1. Either of a pair of folds of peritoneum that attach to the caudal end of the gonads (testes in males and ovaries in females). (wiktionary.org)
2. Embryonic structures which begin as undifferentiated mesenchyme attaching to the caudal end of the gonads (testes in males and ovaries in females). (wikipedia.org)
Word origin: From gubernō (“I steer”) and –culum.