Talk:Paper - Early Stages of Human Development

Fig.1. Photomicrograph of a living humanovum,surroundedbythecoronaradiata, recoveredfromtheuterinetube. X.C.

Fig. 2. A section of the ovum shown in Fig. 1. It shows the second maturation divisionX.C.

Fig. 5. Photomicrograph of a living human ovum showing one blastomere and a numberofsmallcels. X.C.

Fig. 6. A section through the middle of the Hertig-Rock embryo (No. Mu 8020) estimatedtobe71daysold. Thetrophoblastconsistsofathickproliferatingdisc growingintotheendometrialstromaandathinmesothelial-likelayer. Theinnercell mass is represented by an oval mass of cels. X.C. (Reproduced by courtesy of Drs. Hertig and Rock.)

Fig.7. A sectionthroughthemiddleoftheHertig-Rockembryo(No.Wi8004)esti- matedtobe91-daysold. Lacunxhavedevelopedinthetrophoblast. (Reproduced by courtesy of Drs. Hertig and Rock.)

Fig. 8. A photogramograph of an 11l-dayhuman embryo embedded in the endo- metrium. Theinnercelmasshasdifferentiatedintotheembryonicectodermand endoderm. Heuser'smembraneandtheembryonicendodermenclosetheprimary yolksac. X.C. (ReproducedbycourtesyofDrs.HertigandRock.)

Fig. 9. A photomicrograph of a 12-day human embryo embedded in the endo- metrium. (ReproducedbycourtesyofDrs.HertigandRock.)

Fig.10. A generallow-powerviewoftheBarnesembryoestimatedtobeabout 104-daysold. Theextentofthesyncytio-andcytotrophoblastinthedifferentparts ofthevesicleisshown. Theembryonicrudimenthasdifferentiatedintocolumnar ectoderm and embryonic endoderm, the latter is continuous with Heuser's membrane. The extra-embryonicmesoblasthasbeen artificialyseparatedfrom thecytotrophoblast. X.C.

Fig. 11. Diagram to show the development of the amniotic cavity and primary yolksac.

Fig.12. Diagramtoshowthedevelopmentofthesecondaryyolksac,extra-embryonic c(elom and remnant of the primary yolk sac.

Fig.13. Asectionedschematicdimensionalreconstructionofanembryoatthetime of the appearance of the primitive streak.