OVARY (DEVELOPMENT AND INVOLUTION). 



microscope distinct fibrillation, or the cavity 

 is empty and much contracted. 



8. The shrinking having rapidly progressed, 

 the ovisac exhibits deep plications, and the 

 rays are beginning to form, but the yellow 

 colour is still distinct. 



9. The cavity is nearly or entirely oblite- 

 rated. The yellow colour is gone, but the 

 rays remain, and the collapsed follicle now 

 forms a white stellate body with a small cen- 

 tral point (fig. 372. h). 



10. The follicle itself is reduced to a mere 

 point in which none of the foregoing characters 

 can be traced. 



Descending Series. B. After Impregnation. 



11. The follicle has not materially dimi- 

 nished in size. The lacerated opening is 

 closed. The yellow coat is much plicated, 

 and the clot when present shows fibrillation, 

 as in No. 7., or the cavity is empty. 



12. The follicle has acquired greater firm- 

 ness and solidity. The yellow ovisac is much 

 increased in thickness. The folds are not so 

 numerous, but are deeper, though not quite 

 so distinct. Vessels contained between the 

 folds appear to pervade the yellow coat. The 

 white lining of the cavity is formed, and within 

 it is a clear fluid, rather viscid, (fig. 387.), or 

 the centre of the yellow ovisac is solid, and 

 exhibits no cavity. 



13. The central cavity is nearly or entirely 

 obliterated. In the latter case a solid white 

 body occupies its place, extending into the 

 yellow mass in divergent rays. This arises 

 from the plication of the white lining, by 

 which process the cavity is closed. The co- 

 lour of the principal mass is now a dirty 

 yellow ; it is somewhat reduced in size, and 

 its outline is oval or irregular (fig. 389.). 



14. The more prominent features observable 

 in the last condition may still be faintly traced. 

 In size the body measures 2-3'". It is of a 

 pale white, and is chiefly distinguishable from 

 the surrounding stroma by the absence of 

 vascularity in its tissues. Its solidity is gone. 



To return, then, to the two questions which 

 led to the foregoing considerations as neces- 

 sary to their solution, viz. 



What evidence does the condition of the ova- 

 rian follicle afford, first, as to the previous es- 

 cape of an ovum, and secondly, as to the pro- 

 bability or certainty that that ovum has been 

 impregnated or otherwise ? 



It may be concluded that whenever the 

 follicle presents the appearances exhibited in 

 the first series down to and including No. 5., 

 the ovum has not escaped ; although it may 

 not be detected, either on account of the 

 difficulty of finding so small a body, or else 

 because it may have perished by absorption or 

 decomposition. 



In the condition No. 6., an ovum has just 

 escaped, or is in the act of escaping. None 

 of these conditions of the follicle a~ffbrd the 

 slightest evidence of previous impregnation. 

 They have all been repeatedly observed both 

 in Man and animals where the coitus has never 

 occurred. 



Between No. 7. and No. 1 1. it may bediffi- 



571 



cult to draw a positive distinction. No con- 

 clusion regarding the question of previous 

 fecundation, derived from the state of the fol- 

 licle during the first fortnight after the escape 

 of an ovum, would be absolutely safe ; al- 

 though the difference between the unimpreg- 

 nated and the impregnated is such as to afford 

 in every instance at least strong presumptive 

 evidence, for the follicle shrinks rapidly in the 

 former, while in the latter it undergoes little 

 or no diminution in size. 



But after this period there can be no ques- 

 tion as to the prior occurrence of a fecun- 

 dating coitus. Every follicle presenting the 

 conditions described in Nos. 12, 13, and 14 

 has discharged an ovum, which has been after- 

 wards impregnated. Every follicle in the 

 states described in 8, 9, and 10 has discharged 

 or has contained an ovum which has perished. 

 But this proves only that fecundation has not 

 occurred. It affords no evidence whatever 

 that the coitus has not obtained. 



Lastly, it may be observed that if, as is 

 sometimes the case, the follicle fails to com- 

 plete the process of rupture after the first 

 steps of preparation have been made, the ovum 

 may perish or be absorbed without being dis- 

 charged, and the follicle will then shrink and 

 become obliterated, as in the first series of 

 changes. And it is further noticeable that 

 although the number of Graafian follicles ex- 

 hibiting the appearances indicative of the dis- 

 charge or fecundation of ova, may generally 

 be taken to represent the number of ova also 

 actually discharged or fecundated, yet this will 

 not always furnish a safe guide, because one 

 follicle may contain two ova, or one or more 

 ova may have escaped the influence of the 

 coitus which had fecundated the rest. The 

 number of ruptured or altered follicles there- 

 fore will in the first case be less, and in the 

 second greater, than the number of ova or 

 foetuses found in the oviducts or uterus. 



DEVELOPMENT AND INVOLUTION OF THE 

 OVARY. 



The Origin of the Ovary, and the Alterations 

 which it undergoes at different Periods of Life. 



The ovary takes its origin in a separate 

 portion of blastema, quite independently of 

 the Wolffian body, with which it is in close 

 contact. It is not indeed until after the de- 

 velopment of the Wolffian bodies has made 

 considerable progress, and about the time at 

 which the kidneys first appear, that, according 

 to the observations of BischofF on the mam- 

 malian embryos generally, the ovaries are first 

 perceptible. 



In the human embryo the ovary cannot be 

 discerned earlier than the 5-7th week. Nor 

 is it possible at the time of its first appear- 

 ance to distinguish the ovary from the testis. 

 Hence the term "generative gland " has been 

 proposed by Kobelt as the most appropriate 

 designation for a structure which, according 

 to him, is then capable of being converted into 

 either organ indifferently. In a human em- 

 bryo of the fourth week, of which I have 

 given a description in the Transactions of the 



