378 THE GENITOURINARY ORGANS. 



TECHNIC. 



The ovaries of the smaller animals are better adapted to study 

 than those of the human being, since the former are more easily fixed. 



The germinal epithelium and its relations to the egg-tubes of 

 Pfliiger are best studied in the ovaries of young or newly born animals 

 cats, for instance, being especially well adapted to this purpose. 



Normal human ovaries are usually not easily obtainable. Human 

 ovaries very often show pathologic changes, and in middle life frequently 

 contain but few follicles. 



Fresh ova may be easily procured from the ovaries of sheep, pig, 

 or cow in the slaughter-houses. On their surfaces are prominent trans- 

 parent areas the larger follicles. If a needle be inserted into one of 

 these follicles and the liquor folliculi be caught upon a slide, the ovum 

 may as a rule be found, together with its corona radiata. That part of 

 the preparation containing the ovum should be covered with a cover-glass 

 under the edges of which strips of cardboard are laid. If no such strips 

 are employed, the zona pellucida of the ovum is likely to burst in the field 

 of vision, giving rise to a funnel-shaped tear. These tears have often 

 been pictured and described as preformed canals (micropyles). 



The best fixing fluid for ovarian tissue is Flemming's or Her- 

 mann's, either of which may be used for small ovaries or pieces of large 

 ovaries ; safranin is then used for staining. Good results are also ob- 

 tained with corrosive sublimate (staining with hematoxylin according 

 to M. Heidenhain), and also with picric acid (staining with borax - 

 carmin). 



The treatment of the Fallopian tubes is the same as that of the 

 intestine ; in order to obtain cross-sections of a tube it is advisable to dis- 

 sect away the peritoneum near its line of attachment and then distend the 

 tube before fixing. It is instructive to dilate the tube by filling it with 

 the fixing agent, thus causing many of the folds to disappear. 



No special technic is necessary in fixing the uterus and vagina. 

 The epithelium is, however, best isolated with one-third alcohol. 



Seminal fluid to which normal salt solution has been added may 

 be examined in a fresh condition. The effect upon the spermatozoa of a 

 very dilute solution of potassium hydrate ( i Jo or weaker) or of a very 

 dilute acid (acetic acid) is worth noticing. The spermatozoa of sala- 

 mandra maculosa show the different structural parts very clearly (lance, 

 undulating membrane, marginal thread, etc.). In macerated prepara- 

 tions (very dilute chromic acid), or in those left for some time in a 

 moist chamber, the fibrillar structure of the marginal and axial threads 

 may be seen quite distinctly. The spermatozoa may also be examined 

 in the form of dry preparations (treatment as for blood), stained, for 

 instance, with safranin. Osmic acid, its mixtures, and osmic vapors are 

 useful as fixing agents, certain structures being better brought out so than 

 by employing the dry methods. 



In examining the testicle (spermatogenesis) it is advisable to 

 begin with the testis of the salamander, which does not show such com- 

 plicated structures as do the testes of mammalia. Here also either Flem- 

 ming's or Hermann's fluid may be used as a fixing agent, the latter being 



