Abnormal testis morphology Torsion of appendix of testis 2020-09-28T22:15:53Z Twisted vestigial remnant of the Muellerian duct The appendix testis or hydatid of Morgagni, is a vestigial remnant of the Müllerian duct located on the superior pole of the testicle between the testis and epididymis. Although this appendage has no vital function, it is present in 50% of males. Torsion of twisting of this vestigial remnant can be incredibly painful, but usually requires no medical intervention.