564 



UTERUS AND ITS APPENDAGES. 



which produced it closes in the same manner 

 as when conception has not occurred, but it 

 does not shrink rapidly, as in the latter case. 

 On the contrary, the inner coat or original ovi- 

 sac continues to increase in thickness, in conse- 

 quence of a still larger deposit of yellow oil 

 granules in its substance. The outer coat of 

 the follicle or tunic of the ovisac suffers no 

 change ; but upon the interior of the ovisac, 

 and therefore lining the cavity, is formed a 

 membrane, the origin and nature of which 

 will be presently considered ; or else it may 

 happen that the cavity becomes obliterated by 

 the organisation of the clot by which it had 

 been at first filled. 



After conception it is probable that the ac- 

 tual diameter of the follicle does not at any 

 time materially increase. So great, however, 

 are the variations in its size in different sub- 

 jects, that this point scarcely admits of being 

 accurately determined. The Graafian follicle 

 may, at the time of rupture, occupy \, , or i 

 of the entire ovary. These at least are the 

 dimensions which it is usually found to have, 

 in different instances, during the first four 

 months of pregnancy ; but after this period 

 the process of diminution begins to be percep- 

 tible. All the changes which are now observ- 

 able in regard to form, solidity, and other par- 

 ticulars obvious to the unaided senses, and all 

 the histological changes are to be looked for 

 within the outer coat of the follicle. The latter 

 appears to suffer no alteration, but simply to 

 follow the movements of its contained parts, 

 around which it remains loosely applied. The 

 ovisac, however, or inner coat, rapidly in- 

 creases in thickness, in consequence of a more 

 considerable accumulation in its texture of 

 the same yellow oil whose deposition had be- 

 gun in it long before the follicle had ruptured, 

 and when it was only approaching the surface 

 of the ovary. 



This thickening of the inner follicular coat 

 is followed by a twofold result. The mem- 

 brane, being confined by its outer tunic, now no 

 longer distensible, as well as by the surround- 

 ing stroma into which the vesicle has now begun 

 to sink, becomes more deeply plicated ; and 

 since it can no longer extend outwardly, it 

 must of necessity encroach upon the cavity 

 within. The latter thus becomes senMbly 

 diminished, whilst the entire thickness of its 

 boundary wall is in like proportion increased. 



At the end of the first two months of ges- 

 tation, the follicle possesses considerable soli- 

 dity. The wavy and plicated condition of the 

 yellow ovisac is now less distinct. The whole 

 of this coat exhibits the appearance of a thick 

 yellow layer, still occasionally traversed by 

 numerous little blood-vessels, which run across 

 it in straight lines from without inwards as 

 far as its inner surface. The larger of these 

 vessels probably do not actually pierce the 

 yellow coat, but lie between the sulci, repre- 

 senting the original folds of the ovisac, and 

 which, now pressed back to back without 

 being yet obliterated, would still serve for the 

 conveyance of blood-vessels to different parts 

 of the tunic. 



These changes continued to be in a certain 

 sense progressive until the fourth month of 

 gestation, about which time the Graafian fol- 

 licle is usually considered to attain its highest 

 state of development. But if the term de- 

 velopment be admitted, it should be remem- 

 bered that the only apparent purpose of these 

 and other changes which ensue is still the ob- 

 literation of the structures in which they 

 occur. The process of obliteration, however, 

 has at this time not proceeded so far as to 

 have caused the removal or even diminution 

 of any of the original parts composing the 

 follicle, whilst some new structures are super- 

 added or produced by metamorphosis of the 

 original materials. 



The follicle at this period generally affords 

 the best opportunity for observing the changes 

 which result from impregnation. It may 

 therefore be selected fora critical examination 

 of the subject. 



The external condition of the ovary in 

 which such a follicle is contained serves at 

 once to point out the precise seat which the 

 structure occupies. Not only is the entire 

 ovary larger than that of the opposite side, 

 but it appears more swollen, and is perceptibly 

 harder in one particular spot ; over or near 

 this spot a cicatrix may still be visible, and 

 in its immediate neighbourhood are often 

 found some serpentine vessels. If, now, a 

 section be made of the ovary in this situation 

 so as not to pass through the centre, but to 

 include only a portion of the circumference of 

 the follicle, the latter will present the condi- 

 tion represented in./fg. 386. The follicle, in the 



Fig. 386. 



Section of the ovary of a ivoman who died at the end 

 of the fourth month of utero-c/etstation. The Graa- 

 fian follicle of the ovum which had been impreg- 

 nated projects above the stroma. (Ad Nat.) 



a, outer vascular coat (tunic of the ovisac) ; b, 

 yellow inner coat (ovisac), from which a thin slice 

 has been removed, not deep enough to lay open the 

 cavity, hut displaying the brain-like convolutions; 

 e, portion of the follicle corresponding to b. 



form of a little globe, is seen to occupy about 

 a fourth part of the ovary. Its solidity and 

 spherical form cause it to project considerably 

 above the surface of the section. In this way 

 is exposed the outer coat by which the follicle 

 is bounded. Upon this coat numerous blood- 

 vessels, derived from the ovarian stroma, ra- 

 mify. It is the tunic of the ovisac, the origi- 



