P d R T H E N O G E N I ( ' CLElAVAGE I N THE HUAIAN OVARY ONE FIGURE Pathologists and gynecologists have long been interested in parthenogenesis as supplying a possible mecliaiiism f o r tlie explanation of the occui~enceof teratoma in the ovary and testis (Waldcyer, 1 8 i 2 ) . The following evidciice of parthenogenesis in man is presented althougli it is iiot the author's concept of the etiology of teratoma (Kraflia, '38). 111 many forms of life, it is of course well 1mow.n that an egg may undergo development witliout the stimulus of the sperm. 111 otlier forms wherc fei*tilizatioii is tlic normal course of events, the egg may be stimulated to initiate development by the simple cxpedieiit of sliaking, piictui*iiig o r changing the driisitv o r temperature of the sui*i.omicliiig medium. I J mammals, ~ matui~itioiiof the ovum proceeds while the egg is still within thc mil-upturctll follicle. 111 tlic event that ovulation docs not occwr, tlic ovum may contiiiue to develop through the e a ~ l ycleavage stages. This pliciiomeiioii is so common among such mammals as the rat, mouse and guinea pig that at present we use sections of ovary f o r study of ~iiatui*ationin oui. course in embq-ology. Polar bodies and reduction spindles a r e easily found. 111 many of tlicse slides atrctic follicles a r e present which s l i o ~defiiiit ~ e cleavage stages including the two cell stage, four cell, eight cell aiid some few more advanced stagcs. That tlicse are cleavage stagcs rather than the fusion of two 01' more e g g s in polyovular follicles ( a n intcrprrtation made by 19 T H E ANATOMICAL RECORD, VOT.. 75, NO. 1 20 JOSEPH K I ~ A F K A ,JE. Kampmeier, '29) i s clear since an occasioiial cleavage spiiidle is seen. We have liomever iiever seen a stage advanced as far as a n embryonic vesicle such as described by Loeb and made the factual background of liis teratoma theory (Loeb, '12). Tlie purpose of tliis papcr is to put on record obsci*vatioiis hearing 011 the process of pai*tlieiiogeiiesis in man. To our Fig. 1 Untouclird pliotoiuicloArapli of a n ~ r u i i i undergoing cleavage in an atrctic foilicle i n tltc ovary of a 7 )enf-old child. t h e largc discreet 1)l:istoitiere is set off' sh:irply from n sccond h r g e cell and two sni:iller cells. These f o u r cells all lie nitliiii a discwet sliglitly thickened iiiciiihr:iiie, the miia pellueida. KO inmsire g1:inulosa cells m e seen. Note tlie disruptioii of the stratum grnnulosum niid the corona radinta. hlagnificntioii x 100. linowledge this plieiiomeiioii lias been recorded only once, iiaiiielp by Hiiggstriim ( '22). Our sectioiib izrc from the ova1.y of a 7-year-old child. The tissue shows typical ovarian structu1.e iiicludiiig many follicles undergoing ntresia in stages vaiyiiig from graiinlosa disintegration to ndraiiccd corpora dbicantes spuriae. One follicle coiitaiiis ail egg that is clcfiiiite1;v made LIP of four blastomercs. These lie within a definite thickened membrane, PABTHEKOGRNIC CLEAVAGE I S T H E H U M A K OVARY 21 the zoria pellucida, liciice they carinot possibly be interpreted as fusion products of a polyovular follicle (fig. 1). No invasire granulosa cells are within the membrane, as f i*cquently occurs in some ova hence this point of common confusion is not involved. The only additional concept that might he advanced is that of fi.agiiicntation of a degenerating egg since the nnclei are iiot conspicuous. This point is admittccl :zud it might leave the questioii of parthenogenesis ill the higher mammals open, were it iiot for the heautiful illusti*atioii of a similar cleavage stage in mi atretic follicle prcisent,ed by photomicrograph by Saglili (’38) f o r the gibbon. From the foi*cgoingfindings we pi-edict that a careful routine examiiiation by pathologists of all eggs in atretic follicles will uncover abundant material supporting the viewpoint of pai*tlienogeniccleavage in man. LITERBTTJRE CITE]) Il;imxr~iinr, 1’. 1922 Uher degrncratioii ‘ ~artliciiog.enetisclic ’ ‘reiluiigeii V o i l Eizelleii i n normal Ovarieii drs RIeiisclien. A c t a Gync,col. Scaiidiiinv., vol. 1, pp. 137-14.7. K a n r r h i E : ~ ~0. ~ , F. 1929 011 the prohlem of ‘Partheiiogenesis’ in the iii:uiim a l i m ovary. h i . J . h a t . , vol. 43, pp. 45-76. KRAFI~A, Jos., JR. 1936 Teratonin-an eqjlniintioii of its cause hascd on the organizer t.lieory of cnibryology. Arch. T’ath., 1-01.21, pp. 756-764. I>oE,R,L. 1918 ITber rhorionepithelioiiiartige Gebilde iiii Ovariuiii des Meersclii~einchensund iiher ilirc warsclicinlielie Eiitsteliuiig aus parthenogeiietisli sicli ent~vickelndcnEirrii. Zeitscl~r.f . Krebsforscli., uol. ll., pp. 259-282. SAGLTK, S. 1938 Ov-aries of gorilla, rltinipai~zee,orang-utan and gibbon. Contr. t o Embrg-. No. 165, Carnegie Inst. of Wash., vol. 27, pp. 179-190. WALDRYER, W. 1873 Uber melirfaclic i n d i i ~ k t eKernteilung. Areli. f. I’nth. Anat., vol. 5.7, pp. 132-148.