Noun
A part or structure that serves as a guide:
(embryology) Either of a pair of folds of peritoneum which connects the caudal end of the fetal testis with the bottom of the scrotum in a male fetus, and by failing to elongate in proportion to the rest of the fetus causes the descent of the testis into the scrotum; or an analogous cord of connective tissue attached to the ovary in a female fetus, which is the precursor of the round and ovarian ligaments.
(dentistry) (more fully gubernaculum dentis) A cord or sheath of connective tissue that connects the sac of an unerupted permanent tooth with the surface of the gum.
(zoology) The reproductive tract of an invertebrate, or part of it; especially the section containing the gonophores (in a hydrozoan); a sclerotized structure in the cloaca (in a nematode).
(biology) (rare) A trailing flagellum in certain protists used for steering.
Source: en.wiktionary.org