600 



UTERUS AND ITS APPENDAGES. 



can no longer be discerned, and a slightly 

 plaited condition of the lining membrane of 

 the canal begins to be distinguishable (fif$. 

 405. b). 



At this precise point is found the true 

 uterine orifice of the canal, the diameter of 

 which varies in different subjects, but is rarely 

 of larger size than suffices for the easy pas- 

 sage of a common bristle. The true diameter 

 of the tubal cavity at this point is best ex- 

 hibited by a transverse section ; for when the 

 canal is laid open longitudinally, and its walls 

 are separated as at b, in fig. 405. this portion 

 of the interior of the tube appears to have a 

 greater diameter than it actually possesses 

 when the parts are closed, and in a natural 

 state. In some subjects, however, and in 

 certain conditions of the tube, the uterine 

 orifice may be sufficiently patulous to admit 

 of the passage of a fine probe. 



Uterine portion of the tube, pars uterina. 

 This, as just stated, is the portion of the ovi- 

 duct which traverses and is included in the 

 substance of the uterine walls. Its length 

 will vary, in some degree, with the varying 

 thickness of those walls, in different subjects ; 

 yet not entirely so, because this canal does 

 not pierce the uterine parietes in a direction 

 perpendicular to their surface, but traverses 

 them in an oblique manner, while the tissues 

 become gradually attenuated around it, in a 

 direction from within outwards (fig. 405. b). 



But the course of the tube through the 

 uterine walls may be still more satisfactorily 

 traced by the aid of a section made down to, 

 but not laying open, the canal. The peculiar 

 white colour of the tube is thus made to con- 

 trast strongly with the surrounding darker 

 uterine tissue ; and this peculiarity is ren- 

 dered more striking when a fine injection of 

 the part has been made. The canal of the 

 tube may thus be readily traced from its 

 infundibular-shaped commencement running, 

 in the first half of its course, in a direction 

 obliquely upwards and outwards, and in its 

 remaining half, either horizontally outwards, 



Fig. 406. 



Entrance of the Fallopian tube into the uterine 

 cavity, dissected down to the mucous membrane, 

 which is left unopened. (Ad Nat.) 



or more commonly turning rather suddenly 

 downwards, and forming, with its first di- 

 rection, an angle of 60 (fig. 406. and 431.). 

 Strictly, the Fallopian tube should be 

 deemed to commence at this point ; and this 



should be regarded as the true ostium uterinum, 

 while the short infundibular canal leading to 

 it from the uterine cavity should be con- 

 sidered a portion of that cavity, representing, 

 in fact, the cornu of the uterus in mammalia. 

 The peculiar form of this portion of the tube 

 is not without interest, for it appears to me 

 to offer a probable explanation of the occa- 

 sional detention of the impregnated ovum, in 

 its passage through this division of the ovi- 

 duct, where its development produces the 

 variety of extra-uterine pregnancy termed 

 by Breschet interstitial. 



Canal of the body of the tube. While the 

 portion of the Fallopian tube already de- 

 scribed, as contained within the substance of 

 uterine walls, is rightly termed its uterine or 

 fixed portion, the main part, which is ex- 

 ternal to them, constitutes the free portion. 

 This also is traversed in its entire length 

 by a canal, the form of which corresponds 

 generally with that of the tube itself. It is 

 occupied by numerous longitudinal folds of 

 the lining membrane (fig. 405. c), which are 

 so closely placed as to convert the channel 

 of the tube into a series of minute capillary 

 canals. These folds never disappear by dis- 

 tension like the folds and furrows upon many 

 mucous surfaces, such as the oesophagus, blad- 

 der, &c, ; but they are true plications, like 

 the valvulae conniventes of the small intes- 

 tine, as pointed out by M. Richard, who 

 has very accurately described their arrange- 

 ment.* Each of these is composed of two 

 layers of mucous membrane united together 

 by cellular tissue. Their direction is con- 

 stantly parallel with the axis of the tube. In 

 the uterine region of the oviduct, they con- 

 stitute two or three small projecting and 

 rigid crests, forming the little capillary chan- 

 nels, but in proportion as they advance to- 

 wards the outer part, they become more 

 elevated and numerous, and at 2 or 3 fingers' 

 breadth from the uterus commence the large 

 floating folds which are prolonged as far 

 as the pavilion. These floating plaits are 

 from 4 to 6 in number ; they acquire a 

 breadth of 2 3"', and are themselves co- 

 vered by an infinite number of little crests, 

 often imbricated the one upon the other, 

 and intercepting between them little capil- 

 lary canals. On a level with the abdomi- 

 nal opening these large folds cease, the small 

 ones only remaining; but still one of these 

 large folds always extends beyond the ori- 

 fice. 



External orifice, ostinm abdominale. This 

 occupies the bottom of the funnel-shaped 

 expansion or trumpet-like end of the ovi- 

 duct, and is formed simply by a constriction 

 of the tubal walls at a short distance from 

 the irregularly notched margin in which they 

 terminate. The aperture is fringed in its 

 entire circumference by the plications of 

 the membrane already described (fig. 405.). 

 These radiating towards the centre appear 

 nearly to obstruct the entrance of the tube, 



* These, p. 35. 



