Paper 2- An Early Ovarian Pregnancy

From Embryology

Book - Contributions to the Study of the Early Development and Imbedding of the Human Ovum (1908) - Paper No. II. An Early Ovarian Pregnancy Bryce TH. Teacher JH and Kerr JMM. Contributions To The Study Of The Early Development And Imbedding Of The Human Ovum 2. An Early Ovarian Pregnancy. (1908) James Maclehose and Sons. Glasgow.

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By Thomas H. Bryce; John H. Teacher And John M. Munro Kerr, M.B.

Obstetric Physician To The Maternity Hospital And Gynaecologist To The Western Infirmary, Glasgow


The literature of ovarian pregnancy takes us as far back as 1614, when Mercer first suggested the possibility of its occurrence. There seems to have been a common belief that the ovum might be implanted and could for a certain time develop within the ovary. No demonstrative histological evidence was however forthcoming, and as data regarding tubal pregnancy, and the varieties it may assume, accumulated, it became increasingly doubtful whether the early records were not due to inaccurate diagnosis. This opinion was expressed by such authorities as Lawson Tait and BlandSutton. In 1899, however, a careful histological description of an early case was published by Catherine van Tussenbroek, by which she demonstrated beyond question that the ovum could be imbedded in the ovary. Since then her main conclusion has been confirmed by a immber of observers, and it is now universally admitted that such an implantation, remarkable is it may seem, does occasionally occur.

The details of the process of imbedding in the substance of the ovary are not however fully known, nor completely understood. The desideratum is a still earlier chorionic vesicle than any yet described implanted in the gland. Catherine van Tussenbroek considered that her case proved that the essence of ovarian pregnancy was imjJantation of the ovum in a Graafian follicle, but other cases since published do not all bear out this conclusion. The specimen which we have to describe shows that imbedding may occur outside the follicle, and it is especially valuable in respect that the stage of development reached by the chorionic vesicle, is earlier than in any of the cases hitherto recorded. It serves to reconcile the data of previous observers, its histological details throw light on some of the points still at issue, while comparison with the very early ovum described in the first paper helps to explain more clearly the nature of the processes involved.

Catherine v. Tussenbroek justly claims that her investigations furnish incontestible proof that the plasmodium, which covers the villi of an ovum imbedded in the ovary, just as it does those of an ovum imbedded in the uterine mucous membrane, cannot be a derivative under any circumstiinces of the uterine epithelium. The corollary however, that her specimen provides a proof of the foetal origin of the layer, is not fully warranted. Her case affords strong presumptive evidence that the pltismodium is foetal, but it carries us little further than the data on the subject accumulated by Peters. A combination of the data from the two cases described in the present memoir furnishes more decisive proof.

History of the Case

The patient was 27 years of age, had been married for two years, and had one child born eleven months before the present occurrence. During lactation, and subsequently, menstruation was regularly repeated. On November 20th, 1903, she became unwell for the last time, and as menstruation did not recur in December she believed that pregnancy had supervened. On January 1st, 1904, she made complaint of pain in the back and lower part of the abdomen. This recurred at intervals during the succeeding days, and was associated with abdominal tenderness and inclination to faint. On the night of January 8th she had a more severe attack of pain, and on January 9th was seen by Dr. Munro Kerr, who made a diagnosis of extra-uterine pregnancy with the tube probably as yet unruptured. For certain reasons the operation was postponed till January 13th, when the symptoms pointed to rupture having taken place. When the abdomen was opened two or three pints of blood were found in the cavity. On drawing up the right appendages Dr. Kerr was surprised to find that the Fallopian tube was to all appearance normal, but projecting from the free margin of the ovary he observed a haemorrhagic ratuss about the size of a walnut, which he diagnosed as an ovarian pregnancy. The tube and ovary were removed in the usual way, and the patient made an uneventful recovery. The uterus at the time of operation was considerably enlarged, soft and globular, and the presence of an intrauterine pregnancy was suspected. This surmise proved correct, the pregnancy went on to term, and on August 19th, 1904, she was delivered of a full-time child.

The simultaneous occurrence of an intra-uterine and ovnrian i)regnancy is of considerable interest. It will be noticed that labour supervened 8 day's prior to the day anticipated by the ordinary obstetric tables, and the cessation of menstruation had probably relation to the uterine gestation. If 28 days be counted from the 20th of November we reach the 18th of December as the day from which the duration of pregnancy is calculated according to His' rule. The first symptoms of the extra-uterine pregnancy set in on January 1st, and the final rupture came on January 8th. If we assume that fertilization of both ova took place as the result of the same insemination, the age of the ovarian pregnancy may be anything between 14 and 22 days according to His' convention. The stage of development of the chorionic vesicle and embr)^onic rudiment })oints to the age as being (still according to the convention) from 12 to 15 days, so that we must assume that growth and differentiation ceased on the occurrence of rupture of the implantation sac and commencement of haemorrhage from the ovary on January 1st. if this were not the case we must conclude, either that the ovarian ovum was fertilized later than the uterine, or that development was retarded owing to the site of implantation.

Dr. Muuro Kerr, having taken special care in removing the parts to avoid injuring the specimen, placed it in formalin immediately after the operation, and took it to the Pathological Dej)artment of the University where Professor Muir sliced the ovary longitudinally from the free margin to the hilum. The specimen was then placed in the hands of Dr. Tea(ther, who made a sketch of it to scale while it was still in the fresh coiiilitinn. [ii tlip sultscfjiioiit [ixjtti"ii iiinl Ijnril lieciimc somewliiit. {li-stnrted, si> tliiit it \v;i.s iinpoaj section of the entire gland iitui the Jntcifsting Even under the moat fiivonvalile (lireum stances h( of hardened l)lni)d clot provt*s an insuperalilo obsta( in 8|>eeiiiien8 nf this kind. nw\ it ia praetiially ii sections. It was therefore necessniy, as it ha» 1 (lescrilied in the literature, to examine separate sli and iwikc a n;coiistnictiiiii therefrom.

--Mark Hill (talk) 14:05, 29 March 2014 (EST) Text is missing from the following section of the scanned book.

NAKRD-KYt-: nESCUUTIDX OF THK The Fallopian tube appeared to lie slif;;htly tli but was in other respeetft normal. Suhacquent n revealed slicrht oedema of the subperitoneal tiasiiu ; mucous meniiirane presented quite a normal appe; decidual changes. There was no adhesion either the fimlmati'd end of the tube to the ovary. The i enlarged, chiefly in an axis running from the free It was somewhat sharply marked off into two port portion next the broiul ligament was of about iiori the appearanre of a healthy ovary of a woman in tl The surface was fairly smuoth, free from eieatri* iudication exteriiidly of a corpus lutcuni.

The posterior portion of the gland, correspondi ma.'^s mentioned above, was directly continuous sharply delimited from it by change of eohmr. Wl the mass appeared to consist of blood clot, tlio a cousidcrable portion of its cinmmference, was infiltrated ovarian stroma. The blood clot was thu from a rent in the surface of the gland, and rather of the clot was a small fissure betwceu the lipa of \ of villi which proved tx) be one end of a young cho Figure ix is a drawing of the glanrl .split open, c

Description of Specimen

sketch. Oil the cut suifmips a largo irorinm lutmim is seen oi-<',Hpyiiig the lower end of the ovury i4ose up to the hituni. Fully hiilf the aectioii is (^oiifititutcil liy n|i|>jiifiitly norninl ovarinii tissue. The margiiial portion, however, move deejily sli;i<lerl iu the figure, cousisti of likHKl-iiifiltratcd stroma and blood clot. Within tliis |iortioii of the gland, in a .small cavity of irregularly oval shape, lie.s the (liorionic vesicle separated from the coipus luteuni liv a ('onsidcnilile zone of l)lood clot. The knife has cut both the

Figure IX

a.f.. (iruMaii folliulc tillul with I'Inwl, corpus luteum and vesicle une(p'nlly. the greater portion of each remaining in the lateral .segment to the left iti the fignri'. A eomi)lete series of -sections through the whole ovary heing, in the ein-umsranecs, imj>o.ssible, a slice of about 8 mm. thick was titkcn from t)ie outer portion, including the greater part of the corpus luteum and a complete section of the chorionic vesicle. Tliis block of tis.sue was cimvcrtefl into a complete series of sections 8 niicTons thick, and .-Jtained in various \va3's. A second l>ortion of tissue was then taken out from al)Ove the corims luteum to eomi)]ete the .section of tliat stru<'tun' in this plane, and to establish its relation to the rest of the ovary and the blood clot in which the vesicle la5^ From a careful study of the sections from the first block, and adjustment to them of the sections from the second, an accurate picture was obtained of the relations of the corpus luteum, the unaltered part of the ovary, and the vesicle to one another in the longitudinal plane (Figure x). The gland was then cut at right angles to this plane, and two supplementary slices (one from the lateral and one from the mesial half) through corpus luteum and chorionic vesicle were removed and sectioned. By this means a complete picture of the relations of parts in the transverse plane was obtained (Figures xi and xii).

Description of Sections

It has been noticed above that the embryonic vesicle appeared to occupy a small cavity of irregularly oval shape. The sections reveal that this is a space with walls largely composed of recent blood clot, but in part lined by a thin irregular layer of fibrin and ovarian tissue in a state of coaguLition necrosis. To this the villi are attached by characteristic broad trophoblastic masses. The cavity represents the normal intervillous space, for the most part empty of blood. The choriouic vesicle occupies the centre of the implantation cavity. It is collapsed and much folded. Its longest measurement is 1*35 cm., but when rounded out its diameter could not have reached a centimetre The villi measure from 2 to 3 mm. in length, and are covered by the characteristic two-layered epithelium identical in all respects with that of a uterine ovum of corresponding age (Plate X, Figs. 13 and 14). They contain vessels filled with nucleated red-blood corpuscles. Numerous karyokinetic figures occur in the epithelium.

Remains of an embryo were found within the collapsed chorion, but in so damaged a stat<3 that it was not considered worth while to give the time necessary for reconstruction. There is a thick abdominal stalk containing vessels full of nucleated red corpuscles, the yolk-sac is much folded, but shows the development of vessels in its walls. The germinal disc is cut very obliquely, and the presence of a primitive streak or neurenteric pitseage could not be detemiiuecl. Its geueral cliaracters indicate however that the cmhiyo cauiiot liavc been further advanced than Graf V. Spec's embryo " Gle," aud it is probably even younger.

The ii«L'tiun pauses througli tli cacb Bi()« of lliU iLrv nvcrutii: porli

The relations of the chorionic vesicle to the ovary are shown in Figures x, xi, xil, which are drawn from the actual preparations by nitjuns of Jidiuger's iirojectioii a|iparaturt.

Figure x is a reconstruction in the longitudinal plane from sections of the two seiies above mentioned. Figs, xi aud xii represent each a section of one-half of the gland in the transverse plane, and an imaginary interval between them of 3 mm. would correspond to the slice of tissue cut out for the lougitudinal .series. From these figures it will be at once apparent that the vesicle is almost entirely surrounded by recent blood

Figure XI

Figure XII

OL-oupj tliu mouth and centre nf cur[>UB liitenm.

clot. Only at one point does the uhoriou come close to the ovarian stroma, and that i.s opposite a gap in the wall of the corpus luteum.

The sections corresponding to Figures xi and XII show that the sides of the blood clot are clothed for a distance of about 1 cm. from its base by a layer of ovarian stroma more or leas infiltrated with hlood. This lamelhi of ovarian tissue end-s di.stally in a free edge, leaving an interval between its lips of about 2 cm., in which the blond riot is exposed on the surface of the ovary. It is apparent from a study of the sections that considerable haemorrhage had taken plaee shortly liefore the operation, and that the blood had more ex Unisi vel v infiltrated the intervening between a layer of necrotic tissue immediately applied to the villi, and the more healthy, living ovarian tissue forming the outer lamella of the wall of the cavity. A large coagulum was thus formed round the chorionic vesicle, and the whole constituted practically a ** fleshy mole,'* which would dc>ul)tles8 in a short time have been extruded from the ovary into the l)crit()neal cavity.

Tiie relations of the villi to the ovarian stroma arc shown in our (M)l()ur(Ml drawing (Plate ix, Fig 12). It represents a portion of the same H(r<'tion as figured in Figure xir, at a point where the villi have remained in vhm\ aHHociatiou with the connective tissue of the gland. An apparently nninial villus showing both cyto-tr()j)hoblast and plasmodi-trophoblast, and hoini^ irn»gular masses of plasmodium are seen attached to the ovarian tissue. Thn ronniMMivc-tissue lamella api>lied to the trophoblast is completely iH'rrnlir, and (Ih' d(H'[)or layers of the stroma show degenerative changes; al a hi ill tlri^|H»r plane the signs of degeneration gradually fade away, and normal connective tissue is reached. There is no reaction rnrri«M|ionding («» the formation of the thick decidua in the uterus, and tlio dcHlruclivt* changes are much more pronounced; in fact, the appcarancM^rt suggest llh» i)ersistence of the early acutely destructive phase re|ircsentetl by llu» ovum which is described in the first paper. TliiTt^ are a number tif mononuclear cells with large cell-bodies scattered through the ovarian tissue in the zone of attachment of the villi (IMatc IX, Fig. 11!). While some of these are i)robably of foetal origin, repreH(»nting <'ells which have been cast oft' from large masses of hanghans' layer (hOIs, spread out over the surface of the necrotic zone of ovarian stroma, numy are undoubtedly maternal cells. They may Ix; swollen connective-tissue cells, or interstitial cells of the ovary. They are not unlike decidua cells, and if they be swollen connective tissue elenients they would be analogous to the decidutd cells in their mode of development, and would represent an ett'ort on the part of the ovarian tissue to react as the endometrium does, but they are relatively so few in number that they do not constitute anything resembling a real decidua.

The relation of the cliorionic vesicle to the corpus luteum constitutes the most important point in the specimen. This body presents the usual characters of a cori)us luteum of the 2ncl month of pregnancy. Although it approaches (juite closely to the surface of the ovary at the lower end, it has clearly not ruptured upon this aspect of the ghmd, for its walls are here (piite intact. The only break in its contour is directed towards the mass of blood clot onclosinor the vesicle. Fisfure x shows the margin of the opening in longitudinal sections, while Figure xi shows a portion of it (tut transversely. The corpus luteum is approximately globular, but somewhat flattened in the transverse plane of the ovary. The circumference can be seen rounding in on all sides towards the o])ening. The centre of the body is occui)ied by the usual irregular mass of young connective tissue and ])artly organised blood clot. This is continued outwards as a hyaline fibrinous band, through the break in the capsule into the necrotic stroma and blood clot surrounding the chorion, while the normal stroma investing the corpus luteum passes inwards between it and the blood clot, as far as the margins of the fibrin mass protruding through the gap. The apparent width of the gap is considerably diminished if allowance be made for the darker masses represented as occupying its lips in the figures ; these are necrosed portions of the corpus luteum.

It is quite evident from this descrij)tion that the cliorionic v^esicle is situated opposite the break in the capsule of the corpus luteum, and that it lies entirely outside it. The vesicle obviously lies in an implantation cavity excavated in the ovary and now greatly distended by recent haemorrhage.

It may be taken for granted that the spermatozoon which effected fertilization obtained access to the Graafian follictle through the opening on the surface formed by the rui)ture of the follicle. The only other alternative is that the fertilized ovum adhered to the ovary and implanted itself therein from without. The aj)pearances do not at all suggest such an occurrence ; it is, moreover, highly imi)robable. On the other hand, from what we know of the powers of movement of the spermatozoon, the first alternative is by no means far-fetched. We assume therefore that after fertilization the ovum was retiiined within the follicle by the closure of the I'ent in its wall. During the early stages in the formation of the corpus luteum, the ovum

&'>nnti it.-H-i: wirain me -MiiTu^ri!!!' D:tl:»-ii- j^-r l^ a •nmUiv thin; blastficvst fia^i.- :t*^Lf. :if?:rrr ::> c^L^iur-r riir- '.r 'iitr Fujrf;u^ Tiabr. in. the uterine •'ravitv. It: t«>w heii.-iv-H; ^j* x I'erne '.'Vim wi^oltl have •ione. It artai-kni th- wall t 'he :'-[/>l»- .m-e-Mrrii ii^lf in the vas<^alar *"»>i*n«^'-tive ri>.*Tie in:m.riiL;i::riv ■s'lTii"*!*: :h.r ^iisnlrr. ThL* s?*|ueii<?e of event.' U iti»li«-;ice«i ^'V riie^- 'Lze '>r *:ii»r 'r»=^Lk: in rh»r wall «>f thtr •M>rpnis Ititenm. whirh L* o'L-i'i- ribiy L;Lr'^»rr "iLia tV»aii*i in the wall of a Dormal f*n>r^»a* lateam .i f-rjr x^t-k- rifror rie e>*rap«e of the ovum from the fi>IIi«:le. an»i aL^> ny the nam^j^eii ^Lssue La the l:f<* '.'f the opening. The tibrinoa^ an«l f<irtially neii-rjci-: maA* in the m'^ath of the c*>rpU5 liiteum wti: tak^ therefore to •:T»rrv-^t'«'CL'L r«» ihe ti'r.rin e»>ne in the aperture • »f •=^ntr:in«'-»^ in th»^ rtrlv atrrine •'^."^In. '-r :ar lir^r ••i-.titrit-ial tiss^ue known as Reirhert's ^^,v. Having: l*»l^<e4 it^/.f \ii rbi-.- trArr.'W- K\ii*l of 5tn>ma between th*" corpus lat^^ura and the -urta«>\ th^- further t2T»>wth of the ovum has resoltotl in the exten:?ive «:l--tru:ri-ii t..f th»r '.'vary whieh is now visible. We have seen iii the fct {»aper that the ovum tends to pn^iuce in the fir=it instance an im{»lantatit>n 'avity •»{ transversely elon^ratel shape. Here there st.-ems likewise to have lieen greater extension of the destructive rhanf'es in a lateral direction, in'l th*.- ovarian stn^ma had vielded rdaee to f^ mm.

the crrowing blastocyst rather than the corpus luteum : this is probaldy rlue to the nature of this tis-ue. What the l>lasto*;yst re^^uires is a vascular connective tissue, ami this it must have foun»l more reailily in the stroma of the gland.

Discussion of Data

As has been already indicated in the introduction, the early records in the literature of ovarian [)regnancy do not, from the absence of histological detail, bring critical evidence to bear on the i)()int8 which concern us in this paper. It is unnecessary therefore to deal with them here. Since the publication of Catherine van Tussenbrojk's paper a number of well authenticated cases have been put on record. The majority of these have been summarised by Kelly and iVrilroy. In a numl)er of the cases reported, the state of the specimen did not |)ermit of an axjcurate d(?teiinination of the precise relations of the chorionic vesicle to the ovary. We shall therefore in the following discussion refer only to those cases in which such determination was possible, referring the render for the details of other cases to the paper by Kelly and M'llroy.

I. Case of C. van Tussenbroek

The " ovisac " in this instance was a reddish brown mass about the size of a small plum, and it occupied the greater part of the right ovary. The Fallopian tube was in no way attached to the ovary, and being normal was obviously not the primary seat of implantation of the ovum. The mass representing the ovisac had everywhere a smooth surface like that of the rest of the ovary, but at the pole opposite the pedicle there was a small rupture from which hung a shred of blood clot. A section across the ovisac and surrounding tissue, and passing through the point of rupture, showed a chorionic vesicle imbedded in fibrinous masses, and enclosed in a thin envelope of ovarian

rne fi>*^r.ia :ij*=»'tii^. UtT- "iie vi»l jC riii: >it£y 'irvers^t <•> diac the ^ • « «« ^ r-jnmi :ae •■•ir^um:»*r>nin^ ^f 'iie >vj*ai* o«>rnijaij )f laceiii uQbiz^ were fo' rhriii'jrh iItt^t^ :n "a*^ ronn if i :h:n iii!:«tr!7iDCat IiiTer. Tliis U"'r:r 'ir iwrAti cir«ne wt* ai.c a«-w-tv-tr in =:i>a^u-T: Trick die villi •>? the "riiiri'vn : :t iri.^ rT'TrvTrirr^ ^Cfint-**: Sr*.'!!! "iiftrni by n thin Lunelle of n:»ron>» rL^ur- Tjr:i:Vb r-^nn^ni The u-ctlu invet-nni^ii': "t the t.*h«>cioii- The Ir,r#^:r. ru^ii-: •liil n«"iC h-eoiiT-^ Lii-*> •:e'-:*ii:u i;i»L iinietiii piajed no pArt ifi rhe atr^ii'-hmerir -if 'he ovini. A.-* riie iath«>res? rurhtly pxnts oat* r.he ti.-Aiir: ifi whi'Th nh^ ovnsi wa.- :ra.:*ii:»:eti i^presentai the yt>cing ^-onri^'rtive: ti.^-n^ xjiSrh :.- f*>riii*^i w^lriiia the Lotein tissue or theca inf-^rru. in the fir-t ^ta-^e "f or2:anL:?atii.ii 'I't the t!t:.ritrQD? of the rap riir*:^! follick. Xo f^rnLatioQ lik'r \ •iei:i«iiLi ^-is prv:=ent. th«Migh At fir-t, nntil *he reciv^mi.^ it* trie nacnre. the aaiihoress th«>aiht that the broken layer of lutein rrelU represtrnteil dein-lua : the only reaction on the fiart of the ovary to the nee*L* '^f the srowin^j ovum, was a jfreat increj*/te in the vaseularitv of the 5tT»>ma 'flie chorionic ve-*icle was covereti all over by villi which showed pre/ri.v;ly the ••arne ntrrjcture a.^ th'^rie of an intni-uterine ve^irle of the Jiarne .Htajre, The emhrj'o rnea.^are^l 12 ram. an»l was pierfe^.^tiy normal in a|»fi^'ar>in^'^'.

II., III. Cases of Kelly and M'Ilroy, and of Hendes de Leon and Holleman

In the specimens described by these authors there was no formed ('it\\f\iA Ifiteum, fiiJt lutein eelln were found in th»- wall of the implantation iiiy\\y. In the fjr.Ht mentionfid eane the lutr-in tissue was sep;irated from the villi by a thin layer of fibrous tissue, and the conditions of irnphinUition w^-re pnictifjdly identical with those in van Tussenbrceka r;iw, liut the corpiiH luteum hml apparently been distended and spread out over the mass of blood enclosing the remains of the chorionic vesicle. The difference is accounted for by the much larger size of the mass of clot and tissue enclosed in the implantation sac.

IV. Case of Thompson

In this case the ovary (left) was enlarged, and a dark red body about "the size of a horse chestnut" projected from its free margin. There was no adhesion of the Fallopian tube to the gland. The marginal swelling was somewhat separated from the ovary proper during the operation, but the relations of the two parts were <|uite distinct, and there was complete continuity of tissue between them. The red mass enclosed the chorionic vesicle which contained a normal embryo of 12 mm. length. The villi were for the most part in a state of degeneration, but on the better preserved the usual two-layered epithelium was readily made out. About two-thirds of the vesicle projected from the ovary, the remainder being imbedded in a shallow depression within the gland. The projecting portion of the chorion was covered by a thin layer of fibrous tissue, which the author calls the theca externa, but at no point could he recognise lutein cells. On the deep aspect of the excavation within the substance of the ovary, there was well preserved corpus luteum tissue, which extended to the edge of the thin fibrous sac above mentioned. The villi and masses of trophobhist on the deep aspect of the vesicle were attached to ovarian tissue, while masses of plasmodium were seen lying in contact with the theca interna. Nothing resembling decidua wiis seen. The author regarded the ovum as having developed partly within and partly without the ovary.

V. The Case of Hewetson and Jordan-Lloyd

These authors describe a specimen which, in its relation to the corpus luteum differs somewhat from the preceding. The chorionic vesicle was found lying in a mass of firm blood clot in the pouch of Douglas. The Fallopian tube was normal from end to end. The mass of blood clot was "as large as a fist**; the enlarged ovary was iu(!orporated with it, and formed part of the walls of a sac in which the clot lay. Mi(!roscopical examination revealed the presence of villi scattered through the clot, and also imbedded in the ragged walls of the cavity, which wjus thus proved to be a gestation sac. The walls of the sac, where formed by the ovary, consisted of intensely vascular ovarian stroma, which was even more rcti(iular than in the remainder of the gland, the fibres running parallel to the surface. The vessels were greatly eidarged aud thin walled, and many of them opened directly into the gestation sac*. The cavity of the sac was ragged and irregular, large areas having the appearance of fibrin with villi imbedded in it. At no point did the villi actually penetrate to the ovarian stroma.

The membrane lining the sac presented a striking resemblance to the uecrotic layer of the decidua of a 3rd or 4th month pregnancy, but there wns no ti'ac^e of decidual cells in any i)art of the wall. Bulging into the sac from the lower part of the ovary was a large corpus luteum, which was perfectly intact and separated from the gestation sac by a thin lamella of loose and very Vciscular ovarian stroma. In the fibrin layer covering this part of the wall of the sac the imbedded villi were ])resent in relatively greater number. There were no lutein cells visible anywhere except in the intact corpus luteum.

VI. The Case of Franz

In this instance the gestation sac took the form of a fleshy mole situated alongside a large corpus luteum, which showed an interval in its wall next the chorionic vesicle. There was no lutein tissue round the mole, and the general relations were very similar to those in the present ctise, but owing to the size of the chorionic vesicle they are less well defined.

In addition to the above six, a number of other cases have been published with detail insufficient for the purposes of our present comparison, but it may be noted tliat in some instances the absence of a corpus luteum has been recorded, while one or two observers state that they were unable to find any lutein tissue round the gestation sac.

It is apparent from the analysis of these six cases, and the description of the present specimen, that (considerable variety occurs in the imbedding of the blastocyst in the ovary, more especially in respect to its relations to the corpus luteum. Upon one point all observei-s are agreed, viz., that the layer next to the foetal tissue is connective tissue in some form, and that the lutein cells do not play the part of decidua ; indeed, histologically they appear to take no share in the imbedding of the ovum. The published cases may be divided into three (categories according to the relationships of the lutein tissue. (1) It may occur all round the gestation sac, as in two of the cases cited and several others referred to by Kelly and M*Ilroy ; (2) it may appear onl} on one aspect of the gestation sac, as in four of the instances given above ; and (3) it may hv. absent altogether either tis a separate layer or as an intact cor})Us luteum, as in several cases not here summarised, ejj, the cases of Freuiid and Thomd. The second group of cases may be further subdivided into a group in which the corpus luteum is tjuitc intact, e.g. Hewetsou and Jordan-Lloyds case, and a group in which there is a defect in the wall adjoining the gestation sac, cy. in the present case and that of Franz.

Before proceeding to explain the differences which the analysis of the cases reveals, the structure and development of the normal corpus luteum may be briefly considered.

The origin of the lutein cells is still a matter of controversy,* but as regards the human subject the preparations of one of us (J. H. T.) seem quite clearly to indi(iate that, whatever the source of the cells may be in lower mammals, they do not in man arise from the membrana granulosa. In a Graafian folli(^le which is aj)proaching maturity, the membrana granulosa forms a fairly thick layer of cells even apart from the discus proligerus. Outside this there is seen a layer of large oval cells enclosed in the meshes of the innermost layer of connective tissue (theca interna). These are clearly the progenitors of the lutein cells of the corpus luteum, and in a perfectly ripe follicle the layer has developed into a zone of considerable thickness. At either of these stages, a distinct basement membrane can, in favourable preparations, be made out between the young lutein tissue and the membrana granulosa. On the outer side of the lutein layer there are numerous vessels, and as the follicle is about to rupture vessels appear on its inner aspect also. When rupture takes place the greater part of the membrana granulosa is probably shed with the ovum, but shreds of it remain within the follicle, more or less detached from the theca interna, lljiemorrhage and serous exudation now take place into the cavity of the follicle, and it becomes occupied by a mass of coagulum, consisting of a delicate fibrinous reticulum and blood clot in varying proportions. The lutein tissue now develops with great rapidity into a thick layer, the blood-vessels both within and without this layer enlarge, and the (ioagulum is invaded by numerous leucocytes, fibroblasts, and young blood-vessels. The point of rupture on the surface of the ovary is recognisable for a long period, but communication with the cavity of the follicle is frequently, if not always, closed by the formation of young connective tissue internal to, or between the lips of the torn lutein laviiv. Data as to the ra|)idity with which this occurs are wanting, for owing to the fact that ovulation and menstruation do not necessarily coincide, the date of last menstruation cannot be taken as a point from which to estimate the age of an ordinary corpus luteum. Taking however the analogy of a healing wound, there would be a thin layer of vascular connective tissue between the lutein tissue and the contents of the follicle within seven days. If we now apply these data to the matter in hand, it will be seen that there are two possible situations in which an ovum impregnated within the Gnuifian follicle may become imbedded.

  • See a review by F. II. A. Marshall in Q.J, of Micro, Sc, 1905.

There is very good reason for believing, from the data provided by the early ovum described in the first paper, that imbedding commences while the ovum is still a very minute object, little if any larger than the mature unfertilized ovum, that is about '2 mm. Such a minute body might readily find a suitable nidus in the thin layer of young connective tissue within the follicle. Van Tussenbroek's ovum must have lain to one side of the central coagulum, as she herself concluded ; in its growth it disturbed the outer part of the corpus luteum and to a great extent broke it up, while the inner portion remained intact.

On the other hand, if it be admitted, as we believe it must, that the primary and essential factor in determining the eftective implantation of the ovum be a rich supply of blood, the conditions just external to the layer of lutein tissue are still more favourable, and accordingly it appears that in the present case and that of Kraiiz the ovum htis burrowed out of the follicle into this lamella, and lies separated from the corpus luteum by a narrow zone of ovarian stroma except at one point. Here the wall of the gestation sac is directly continuous with the interior of the corpus luteum by a band of tissue of doubtful character and more or less in a state of necrosis. This strand is perfectly comparal>le with the cone of fibrinous material occupying the point of entrance in the Teacher-Bryce ovum (Plate iii, Fig. 3), and may, as has been already explained, be interpreted in the same way. Whether this point of perforation correspond to the region of rupture of the follicle or to some other point is immateriid, because we know that the process of imbedding cannot begin till at least seven days after fertilization, by which time the follicle would be again closed. While this interpretation satisfactorily explains the position of the ova in these cases, another possibility may be admitted, viz., that the ovum was arrested between the lips of the wound in the follicle, was there fertilized, and was then imbedded in the vtiscular stroma outside the follicle. If this were so the fibrinous and necrotic tissue occupying the gap in the follicle wall might be due to the destructive process extending inwards towards the heart of the follicle. The imbedding in the case of Thompsons ovum, which la}^ in the splayed-out mouth of the follicle with no lutein tissue either on its free surface or between it and the corpus luteum, may have occurred in this way.

The fact that in our younger stage the chorionic vesicle lies wholly without the follicle is in favour of the first alternative, which moreover presents a more complete analogy to the conditions in a uterine implantation. The further growth of the ovum and extension of the destructive activity of the trophoblast would obviously have brought about the same condition of things as in Thompson's case. If the case had proceeded further without rupture of the ovary, the ultimate result would presumably have been destruction of the corpus lutcum. The series of cases in which intra-follicular imbedding had occurred show that in these also the final result would be disnppearance of the lutein tissue, so that in the final issue the initial differences due to variation in the site of implantation w^ould disappear, after a few weeks or months. Variation in the site of implantation is due then only to differences in the degree to which the ovum burrows into the connective tissue of the ovary, and the cases readily arrange themselves in series on that basis.

The case of Hewetson and Jordan- Lloyd forms the extreme term of a series of which the case of van Tusscnbroek is th(3 first term. It represents a case in which, prol)al)ly at a comparatively early stage, the gestation sac had ruptured and abortion had taken place into the pouch of Douglas. The present case is an instance of a cliorionic vesicle caught in the course of such an ovarian abortion. While Hewetson and Jordan-Lloyd conclude that the case is one of primary implantation in the substance of the ovary, they are inclined to the view that the ovum, either fertilized or unfertilized, reached the surface of the ovary, but being prevented, possibly by adhesions from reaching the Fallopian tube, burrowed back, as it w^ere, into the substance of the gland. While the possibility of such an occurrence cannot be excluded, the case fits in with the other recorded cases, and with the present specimen much better if considered jis a further stage of burrowing from within. The conditions of imbedding revealed in the early ovum described in the first paper embodied in this publication — its complete inclusion, the excessively minute size of the sealed point of entrance, indicating the very early stage at which imbedding occurs — seem to remove the difficulties, which, on account of the continuity of the thin layer of stroma intervening between the gestation sac and the (corpus luteum, impelled Hewetson and Jordan-Lloyd to interpret the appearances in their case as due to burrowin<iC of the ovum into the ovary from without.

The factors of ovarian pregnancy appear, in short, to be fertilization and retention of the ovum within the Gnaafian follicle, or in its immediate neighbourhood, until such time as it becomes capable of imbedding itself by its own activities, when it may do so in any patch of connective tissue which is sufficiently large to accommodate it and sufficiently vascular to meet the demands of its nutrition.

In the present ease, as in all others recorded, there is no formation resembling decidua. In this matter the early uterine ovum sheds light on the facts of ovarian pregnancy. It has revealed a stage in the process of imbedding in which destructive changes exceed, or perhaps better precede, constructive decidual changes. The formation of a decidua in the immediate neighbourhood of the ovum is not essential to its imbedding. The blastocyst implants itself in the tissue of all others best capable of reacting to the stimulus of an irritant or foreign body, viz., connective tissue. In uterus, tube and ovary alike, the reaction is manifested, in the first instance, by enlargement of the vessels. In the uterus there is soon extensive formation of decidua, but in the ovary the actively destructive changes persist to a later stage than in the uterus. This fact, along with the absence of a decidua, points to the conclusion that decidua formation is a provision of a consei'vative nature, by which during the early months the activities of the trophoblast are limited and controlled until such time as placentation is complete.

Lastly, ovarian pregnancy finally excludes the theory that the uterine epithelium can have any part in the formation of the j)lasmodium. The fact that neither the membrana granulosa nor the lutein tissue has any part in the formation of the investment of the villi in an ovum imbedded in the ovary, limits the possibilities of a maternal origin of the layer of syncytium to the connective tissue. The wholesale destruction of tissue in the ovary and the characters of the early stages of an ovum imbedded in the uterus quite put out of court any theory which has as its basis the idea of an interlocking of foetal and maternal tissue, and with it the derivation of the plasmodial layer from maternal endothelium. The fact that the tissue round the chorionic vesicle in the ovary is everywhere clearly recognisable as necrotic connective tissue, while it is strong presumptive evidence in favour of the wholly embryonic origin of the plasmodium, cannot be admitted as a decisive proof of that contention. When we consider, however, the nature of the processes involved in the implantation of the blastocyst, more especially in the early stage revealed by our uterine ovum, it may safely be affirmed that, if further proof were needed, the results of our investigations establish beyond all doubt that the phusmodium is in the human subject a product of the foetal ectoderm.

Literature Cited in the Text

Ahlfeld. " Beschreibung eines sehr kleineii menschliclien Eies." Arch, f. Gyndk.y 1878, Bd. xiii. p. 241. Bkigkl und Lowk. " Beschreibung eines menschliclien Eies, etc." Arch. f. Gyndk.^ 1877, Bd. xii. |). 421. Van BfaiNBDKN. Bulletin de VAavleniie Royale Belgique, Jan. and Feb. 1888. Van Benedkn. AncU. Anzeiger, Bd. 16, 1899. Beneke. "Sehr junges menschliches Ei." MonaLsschr, f, Gebartsh. u. Gyiuik., 1904, Bd. xxii. p. t71. Bland-Sutton. "Menstruation in Monkeys." Brii. Gynaecolog. Journ.y 1880, vol. 2. BliAND-SuTTON. Surgical Diseases of the Ovaries aiui Fallopian Tubes. Cassel & Co., London, 1896, 8vo, p. 9. Bland-Suiton and Giles. Diseases of JVoinen. Rebraan, London, 1906.

Breuss. (Ciled from Merttens) Wiener lived. fFochenschift, 1887, No. 21, p. 502. BuYCE, T. H. Quain^s Anatomy y xi. ed. vol. i. "Embryology." 1908. Bukckhard. "Die Implantation des Eies der Maus, etc." ArcJi. /. mihr. Anat.y 1901, Bd. 67, p. 528. CoVA, Ercole. Arch, f Gyndk.y 1907, Bd. 83, p. 83.

DuvAU "Placenta des Rongeurs." Jirarn, de VAnat. el de la Phys., 1889-1892. Eteknod. Anat. Anzeiger, 1898, xv. Nos 11 and 12, p. 181. Franz. Hegar's BeUrdge z. Geburtsh, w. Gyndk, 1902, Bd. vi. p. 70. Frassi. Arch. f. mikr. Anat., vol. 70, p. 492. 1907. Freund, H. W. und Thom6. Virchow's Archiv, Jan. 1906. Heape. "The Menstruation of Semnopithecus entellus." Phil. Trans. B., 1894, vol. 185, p. 411. Heape. "The Menstruation and Ovulation of Macacus rhesus." Phil, Trans, B., 1897, vol. 188, p. 135. Ueape. "The Menstruation and Ovulation of Monkeys and the Human Female." Obstet. Trans., 1898, vol. 40, p. 161. Hhiape "The Sexual Season of Mammals and the Relation of the Pro-Oestrum to Menstruation." Quart. Joum, of Microscop, Sci., 1900, vol. 44» p. 1. Hertwig, O. Handbudi der Entwickelungslehre, etc. Gustav Fischer, Jena, 1902-1907. Heukelom, S. v. Arch, f Anat. u. Phys. Anat. Ahth,, 1898, p. 1. Hewetson and Jordan-Lloyd. Brit, Med. Joum., 1906, vol. ii. p. 568. Hls. Anaiomie vnenschlicher Embryonen, 1880. Leipzig. Pt. 2, p. 74.

iinw:Ui$ASs iimI Lisuksthki^ •* EieinWtong." Z^ralU. /mf Gwt^L. 1903, H. 12, \\n¥¥HVAVM. XniArhr, f. fj^hurijffi, u. OvnaL . BL xxxv. H. 3. \k 4U.

WiHfiVA'M't. * Pla/;4!5fitatiofi of Krinaceuff Eiiropaeu#.~ <i^rf. Jomrn. *»j Micro^t/iK Sri ^ liS89, vol XXX, p, 283. Ut:Miyj'in\ "l>i« Pliy|r/geri»?»^ d«r« Amnions und die B€<l»fiilnng des Trophoblastes." (^f/rknvdL thr Konil:. Amd, r. W dt^ivf^hr . U AmM^dam^ D. 4, No. -"i, 1895. Ut'HHyj'Ur **Di«; Keimlda^c von Tamu*." F^M^hrijl fur G^genl<auer, Leipzig, 1896. Hi:myj:m, ** Pla/^;nU von Tar»iu« und Tupaia." /V<^. o/ Internal. Cmg. of Zoology, i iiuihr UliiHf 1H98, iUnnyji'm', "Fnrchung und Keimblattbildung von Tarsiug spectrum." Ferh. Kgl. Akad, IFf^hriMrhnJ/m Ain'.hr(lnm, S. ii. I), viii. N. 6, 1902. Jk.SK(Nh4;N. "i'la/;ciita of the Mou«e." Tijdachr. d. Sed, UUrk. Vereen. (2), Dl. vii.

All, 3. JoNKM, WllAinriN. /'/«/. 7W/71X., 1837, p. 341. Quoted in Teacher's Catalogue of Anat.

aiul I 'alii. /'r/'/fM. of If^rn. Ilnnfer, 1900, MacLehose, Glasgow, vol. ii. p. 723. ,U)Sii. MuiuilHm'.hr, f. (It'hurtHh. u. (lijiuik., 1907, Feb. xxv. H. 2, p. 279. MvMWAu "Kin Hi'lir jiingifH nicnschliches Ei." ArcJi, f Anut. u. Phys. Anal, Abtk, 1890, p. *jr»o.

KKlltKh. Nm mmtnfdn :. Kjitwidrluvffsfjfsr/tirJtte der JrirbeUhiere. Pt. I. Evtwickelung des SrlumtifM. Jfna, 1897. KklLY iind McjIliioV. Joum. of (fhslH. and (iifii. of British EmjnrCj vol. ix. p. 389. Koi.LMANN. " MmiMclilichen Eit*r von G mm. Grossc." Arch, f Anal. u. Phys, Anal JIdh., 1879, p. 275. LkoimiiJ). l/lt'ruM und Kind. S. Hirzol, L<'ipzig, 1897. LkoI'oi.d. /'Hh srhr juiujrs intmsr/iUHu'M hJi. S. Ilirzel, Leipzig, 1906., Fkanklin I*. ** l*iithol()^)' ol Kiirly Human Embryos." Johjis Hopkins Hosjntal l!i'/n>rtM^ 1900, vtil. ix. p. 1. MAl«tllANh. " lU'dbarhtungcn an jungon menschlichen Eiern." Anatojnisrhe Ilefte, Bd. 21. Mahniiali., F. II. A. ••Tlio Oestrus Cycle of the Sheep." Phil Trans. B., 1903, vol. 19G, p 17. MAHHilAl.h luui Jolly, W. A. "The Oestrus Cych^ in the Dog," ibid. 1906, vol. 198, p. 99. Mahhiiall, Milnks. I'nti'hrati' Kmhryohnpi. Sniitli, Elder i^ Co., London, 1893. Mi'LINHiNtiH. •* Knlwiokolung des Eies dor Mans." Arch. f. niikr. Anal., 1907, vol. 70, p. ri77. MiCNhKH hK LkoN and Hollkmann. Iktvut dc (HyncculiHjie, June, 1902 MkuiTKNS. Xcdschr, f (t\hurtsh. nnd (iynak., IMM, vol. xxx. pt. 1, p. 1. MiNor. /.ii/N»Hi/i»rv Tf.t't titmk of KminyohHiy. Hlakiston's Sons, Philadelphia, 1903. Pkvkum. 11. Ihf Hinbtttuhij dfs menschlichen Kics, etc. Deuticke, Vienna, 1899. IvArsriUU. /tntndbL :, (iynak., 1907, p. 794. Kkuukkt, ^i'ilod fixun LtH»pold, **rteius nnd Kind.") Ahhamll. der Konitji. Akad. d, irtSs^HA'K IWrlin, IS73.

liossi DoRlA. Archiv f. (hjiUiL. 1905, B(i. 76, p. 433.

Selenka. Stmiien Uher die Evfirirkchimjuffcsrhiclite der Tiere ; (Memchenaffen). Parts 8 to 10, 1901 to 190G. Kreidel, Wiesbaden. SoBOTTA. Arch, f. mikr. AnaL, H<1. 45, H. i. 1895, and Bd. 61, 1902. V. Spek. Arch. f. Altai, nnd Phya. Anal. Ahth., 18('^9, p. 159. V. Spek. Arch. f. Anal, und Phi/a. Anat. Ahth., 1896, p. 1. V. Spke. *'Die Implantation des nieerschweinchen Eifs." Zeitschr. f. Moiphologie u. Anthro poloffie, 1901, Bd. iii. H. i. p. 130. V. Spek. Verhandl. deutschen Gcs. f. (Iffiu'ik. Leipzig, 1906 (Kiel, June 1905), p. 421. Stolpkr. Mojiatsschr. f. Geburtsh. und (ri/naL, 1906, vol. 24, p. 287. Teaohkr. Catahffjue of the Anat. and Path. Preparations of Dr. JV. Hunter. MacLeliose, Glasgow, 1900. Teach KR. Joum. of Ohatet. and Gt/n. Brit. Em p., 1903, vol. iv. p. 1 and p. 146. Teach KR. Ja^irn. of Path, an/l Bact., 1908, vol. xii. p. 487. Thompson. American Gynecology, 1902, vol. i. p. 1. Tus8ENBR(EK. Annates de Gynecohnjie, T. Hi. p. 537. Webster. Uuman Placentation. Keener & Co., Chicago, 1901.


Plate I An Early Human Ovum Imbedded In The Decidua

Km. I. SiTTinN TMuoruii TiiK OKciDrAi. L<im*i.K, figurwl on yn^Q 10. Photograph at a iiia>'iiilirjiliuii of 'JT i». f^ u|)|m'I' ImuhIit ; />, lower boi*(ler of lohule ; Jn.g., mouth of a i;l.iiii| ; /M". . |»«iint of nitrancr.

MiMiion «'utM thr lolmli' ill thr loiij; axis of the shi-ed of ckH.'idiia. The free surface it I III- imiruUM inmiltrant* lirs to th»' left, the deep surface Uy the right. In the centre \H :nrii I he rax it V of th«' Mastocyst. Hound it is a nuiss of in*egular plaAnio<lium onupMiiv, <'>•' Mood li I led implantation ravity. The swollen decidua showB dilated ^•l.uhU, .iiid niutli t«nl:ir^cd vessels. Near the deep surface the vessels are dilate<l into iiliiiiini MiiMiN Iik(« ihanui'ls. Thei-e is a haeinturhage in the upj)er {jart of the section.

Tin- plii»ini(iapli n'prrNi'uis at a lower magnification the sjinie section as drawn in mIiiiii till IMatf III.



Fig. 3. Section Through Blastocyst and Implantation Cavity at the level of the jKniit of eiitiance. x 100 1). dec.y decidua ; n,z., necrotic zone of decidua ; /'.A'., point of entrance ; gl.y gland ; hl.v., niat<;rnal capillaries : ///jr., haemorrhage.

the cavity of the trophoblast is at this point tilled with niesoblast. The ct^totrophoUast appeal's as a blue-pink lamella ; the plasnwiii -trophoblast as bands and thi*eads of protoplasm stained of a dusky-red colour enclosing nuclei. The spjwes in the plasniodium are occupied by maternal bhKKl corpuscles. These come from maternal capillaries opened up Jis the implantation cavity enlarges. In the upi)er part (»f the section thei*e has l>een a considei-able haemorrhage into the decidua ; this has in pai-t broken down the necrotic zone, and the mass of effused blocnl hsis imrtly torn up the plasmodial bands. The implantation cavity is lined by a necrotic zone of the decidua distinguished by its pink colour ; the unaltered parts of the decidua have a grey-blue tint. Within the necrotic zone are seen numbers of free cells. The glands of the decidua are dilated ; their epithelium is desquamating, and their lumen contains I'ed and white blood corpuscles. The blood-ve«sels are much dilated, more especially on the deep aspect of the decidua, where they form almost sinus-like spaces ; to the right and below, the endothelium of one wall of such a vessel is seen covering the decidua. the decidua is ci-owded with leucocytes. The point of entrance shows a depi*ession filled with a mass of fibrin ; continuous with this and with the necrotic tissue, a fibrinous spur projects into the implantation cavity.


Fig. 4. Section of Blastocyst. x200d.

The cyto-trophoblast appears as a blue-pink lamella with irregular nuclei. Directly continuous with it are strands of plasmodiuni ; only the central strands of the plasmodium are represented. The mesoblast is shown as a mass of mucous tissue. The delicate blue reticulum which forms its base is largely a precipitation product ; in it are numerous small rounded or spindle-shaped cells, which form a very loose syncytial tissue. The mesoblast has shrunk away from the cyto-trophoblast on the left, and in the centre is the retraction cavity containing a portion of the torn amnio-embryonic vesicle.


Fig. 5. Section of a Portion of the Wall of the Blastocyst, showing cyto-trophoblaat and plasmodi-trophoblast, with portions of decidua, and the opening of an enlarged sinuslike capillary into the implantation cavity. x 350 D. c?/^, cyto-trophoblast ; dec, decidua ; e7id., endothelium of maternal capillary ; pL, plasmodiuni ; n.2.y necrotic zone of decidua.

The cytological chamcters of cyto- and plasmodi-trophoblast are here brought out. The section jmsses through an opening, eroded by the plasmodiuni, in the wall of a large sinus-like capillary. The endothelium is still ijartly preserved, and covers the upper portion of decidua. The vessel opens by a wide gap into the implantation cavity, and the opening is partially occupied by a large mass of irregular vacuolated plasmodium. This is continuous with the necrotic zone of the decidua, from which it is distinguislied by a difference in colour. The plasmodium is not continuous with the other poition of decidua ; between them there is a narrow space containing a few leucocytes. Under the endothelium there are several large apparently degenemt^d decidual cells. The guiding line to the endothelium touches one of these cells.


Fig. 6. Si-x^tion of a Portion of the Nkcrotic Zone of the Decidua, and of the Layer of Large Oeli-s on its Inner Aspect. x 500 d. n.z,, necrotic decidua ; w.c, large, prolwibly maternal, cells in various stages of degeneration, some lying free in the implantation cavity, othera embedded in the necix)tic tissue ; cav,, blood-filled implantation cavity.


Fig. 7. Tangential Section through the Blastocyst Wall, showing cyto-trophoblast and plaHniodi-trophoblast. x 320 D. pl.^ plasinodium ; nuc.^, cell with large single nucleus ; nucr^ cell with two nuclei.

The cellular layer shows great irregularity in the size of the nuclei ; many cells show two, othei's three, some multiple nuclei.

Fig. 8. Section of the Amnio-Embryonic Vesicle, x 320 d.

The drawing repi-esents the walls of the vesicle restoi-ed by the superposition of three successive sections. The mesoblast is slightly indicated, and the vesicle is seen to be attached more closely and firmly at one point.

Fig. 9. Section of the Entodermic Vesicle, x 320 d.

Some of the surrounding mesoblast cells and threads are represented.


Fio. 10. Section showing a Mass of Vacdolated Plasmodium Invading the Decidua. Photograph. X 350 D. pL, Plasmodium; dec., decidua; n.^., necrotic zone of decidua.

The mass of plasmodium shows a number of small vacuoles. It lies in a l)ay of the necrotic zone, and between the two are several large free, probably maternal, cells. the decidua is crowded with leucocytes. The decidual cells adjoining the necrotic zone show the early stages of degeneration ; further out they are more normal.

Fig. 11. Tangential Section of the Opposite Pole of the Cvto-trophoblastic Sphere from that figuied in Fig. 7, Plate VII. Photograph. x 350 d.

The nuclei are very irregular. The well-defined central cells belong to the innermost layer of the cyto-trophoblast.

Plate IX


Plate IX

Fig. 12. Section of a Portion of the ovarian stroma and villi of the chorion. X D.

r, villus ; 7r.j of lijinglians' layer cells ; />/., ])lasm(Kliuiu ; hf.r., lilood clot ; /i</., luieiiionliage ; sfr., stioiiia of ovary; W./;., hlood-vessel in stroma.

A portion of the stroma lias been selected in which runs a large vessel ; this, wlien traced thniugh the sections, was found to o|)en out into the gest«ition sjic The stroma adjoining the wivity is necrotic. Masses of pliusmodium are .seen attached to it, ImiIIi on the right ahove the haemorrhage, and to the left alK)ve the blood- vessel.

Plate X

Fig. 13. Section of the Villi and Edge of the Chorion. Photograph. x 140.

The section demonstrates that the villi are covered by a double- layered epithelium (cellular layer and plasiuodial layer).

Fig. 14. Section of a Single Villus and Mass of Langhans' Layer Cells, more highly magnified than in the last figure. Photogmph. x 240 d.

The two-layered epithelium covering the mesoblastic core of the villus is well seen. The mass of Langhans' layer cells is covered by a very distinct plasmodial layer (syncytium of autliors).

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