344 HISTOLOGY 



fibers occur only around the appendages. The wall of the duct itself con- 

 sists of an inner dense layer of connective tissue with circular strands, and 

 an outer loose layer (adventitia). 



APPENDICES AND PARADIDYMIS. 



The appendices are frequently called hydatids, which is a general term for watery 

 cysts. The appendix testis is a small lobule of connective tissue projecting from the 

 groove between the head of the epididymis and the testis (Fig. 346). It is quite 

 constant, having been reported in 90% of the testes examined. 'The projection 

 is covered with the peritoneum of the tunica vaginalis, which may be thickened around 

 it, or corrugated, suggesting the fimbriated orifice of the uterine tube. The appendix 

 consists of vascular connective tissue and encloses a canal, or fragments of canals, 

 lined with simple columnar epithelium which is sometimes ciliated. It is generally 

 not cystic, and it may be pedunculated, so that the terms "hydatid of Morgagni" 

 and "sessile hydatid," formerly applied to it, are inappropri- 

 ate. Although its canal has been reported as connecting 

 with the seminal ducts, this is not now believed to be the 

 case; the structure is regarded as the degenerated end of the 

 Miillerian duct. 



The appendix epididymidis (stalked hydatid) is not always 

 present. Among 105 cases examined by Toldt it was found 

 twenty-nine times. It consists of loose vascular connective 

 tissue covered by the vaginalis, and contains a dilated canal 

 lined with columnar epithelium, sometimes ciliated. The 

 canal generally has no connection with the tubules of the 



FIG. 346.-FRONTVIEWOF e P idi dymis. It is regarded as a persistence of detached 

 A TESTIS, somewhat re- degenerating Wolffian tubules, or possibly of the terminal 



duced. (AfterEberth.) 



a. e., Appendix epididymi- portion of the Wolffian duct. 



Sii^c."ef, P cap e u n tepf- The paradidymis, according to Toldt (Verb. Anat. 

 didymjdis; t, testis; t. Gesellsch., 1802, pp. 241-242), occurs in two forms. The 



v. t tunica vaginalis. 



first is found frequently, but by no means regularly, in 



older embryos and in children. It is a round or elongated structure, conspicuous 

 because of its white color, found on the ventral side of the spermatic cord, either behind 

 the head of the epididymis or higher up. Microscopically it is seen to be a thin, coiled, 

 blind canal, expanded in places, and lined with a simple columnar epithelium. Occa- 

 sionally there are two to four such structures at varying distances from one another. 

 In later years they all disappear. They never contain spermatozoa. 



The second form of paradidymis was found by Toldt in late childhood and in adults, 

 but it does not occur regularly. It is always immediately behind the head of the 

 epididymis and in front of the pampiniform plexus. It consists of a canal, sometimes 

 with saccular dilatations, which is easily followed with the naked eye. The tubule 

 may be closed at both ends, or one end may connect with the epididymis or testis; 

 sometimes one end connects with the testis and the other with the epididymis. These 

 tubules may contain spermatozoa, and they have been said to resemble the efferent 

 ducts in structure. They may be ciliated. 



Toldt regards the first form of paradidymis as due to persistent Wolffian tubules, 

 and the second as a late separation of an efferent duct from its connection with the 

 epididymis. He notes that the second form may give rise to cysts of varying size. 

 Other cysts in the vicinity of the epididymis are said to arise from inpocketings of the 

 tunica vaginalis. 



