pr.emb. ect,— 
; \ae 
Pr. em». ent. —Qe 
Fig. 10 Two egg cylinders of the albino rat found within the same decidual 
crypt, with in part common ectoplacental cone. X 150. Rat No. 87, 9 days 
after the beginning of insemination. ect.pl., ectoplacental cone or Triiger; 
p.ect., parietal or transitory ectoderm; v.ent., visceral entoderm; ex.ect., extra- 
embryonic ectoderm; pr.c.; proamniotic cavity; pr.emb.ect., primary embryonic 
ectoderm; pr.emb.ent., primary embryonic entoderm; mes., mesoderm. 
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