464 



STRUCTURE OF THE VAGINA. [SECT. 207. 



thickened, yet it is doubtful whether new nerve-tubes really arise 

 in them. It is certain, however, that the existing elements in- 

 crease in breadth and length, retain their dark-bordered contours, 

 and can be traced further into the substance of the organ than at 

 other times. 



Fig. 189. The diminution of the uterus after parturition, 



a and the re-establishment of a condition resembling 



though not identical with that which preceded con- 

 ception, takes place in the several parts of the organ 

 in a slightlv dift'ei'ent manner. In the muscular coat, 

 an atrophy of the contractile fibre-cells is obviously 

 the chief means of reduction, inasmuch as, three 

 weeks after birth, these elements again present the 

 same length (o"c>3"') as in the virgin uterus, while a 

 formation of fat is going on in their interior: still, 

 however, a complete absorption of certain muscular 

 fibres may be superadded to this. The case is dif- 

 ferent with the mucous membrane, which is com- 

 pletely thrown off after parturition in the form of 

 the decidua and placenta uterina, and thus has to 

 be entirely formed anew- The more intimate pro- 

 cesses of their regeneration, which is unique in its 

 kind, have not yet been followed, still it is more than 

 probable, that it is completed within the first two or 

 three months after child-birth. It is obvious, also, 

 that the serous coat, and the vessels and nerves of 

 the uterus, enter into a retrogressive metamorphosis, 

 though the particulars of this change have not yet 



?. 



Muscular fibre- 

 cells ot the uterus, 

 three weeks after 

 parturition ; of a 

 pale appearance, 

 from being treat- 

 ed with acetic 

 acid. a. their nu- 

 clei ; 7. fat-gra- 

 nules in their in- 

 terior. Magnified 

 3o0 times. 



been investigated. 



§ 207. Vagina and External Parts of Generation. — The walls 

 of the vagina, one line in thickness, consist of an external fibrous 

 coat, a middle muscular layer and a mucous membrane. The 

 fibrous coat, thin and whitish, consists of a connective tissue, with 

 numerous elastic fibres and networks of veins ; externally it is 

 more lax, but it is denser at its internal aspect where it passes 

 without any line of demarcation into the second coat. This 

 stratum has a redder colour than the outer coat, and contains # con- 

 nective tissue and numerous veins, together with a considerable 

 number of well developed smooth muscular fibres, which are parti- 

 cularly well seen during pregnancy. The fibre-cells, 0*04"' to 

 o - o8'" in length, are arranged in transverse and longitudinal 



