eG 
oie) 
ees 
7 le; 
owe 
= 
@ge 
‘I 
ig 
ee 
c ee 
2 
=e 
is 
ey : 
pr.emb.ect.-~ \ 
\ 
4 ~~ pr.emb.ent-~— 
33! 
Fig. 27 Longitudinal sections of egg-cylinders of the albino rat showing 
fusion of the antimesometrial and the mesometrial portions of the proamniotic 
cavities. > 200. A, rat No. 81, 7 days, 22 hours; B, rat No. 96, 8 days; C, rat 
No. 94, 8 days, after insemination; ect.pl., ectoplacental cone or Triger; p.ect., 
parietal or transitory ectoderm; ez.ect., extraembryonic ectoderm; ect.ves., ecto- 
dermal vesicle, with wall composed of primary embryonic ectoderm, at + junc- 
tion with the extraembryonic ectoderm; a.met.pr., antimesometrial portion of 
proamniotic cavity; met.pr., mesometrial portion of proamniotic cavity; pr.c., 
proamniotic cavity; v.ent., visceral entoderm; pr.emb.ent., primary embryonic 
entoderm. 
325 
