16 



EDWARD MCCRADY, JR. 



pr., pronucleus 



p.r., posterior ridge 



p.s., peri-intimal space 



p.t., pronephric tubule 



K., Eathke 's pouch 



r., rectum 



r.b., residual body 



s., somite 



sac., sacculus 



s.c., seam of closure 



s.ch., serous chorion 



s.e., endolymphatic sac 



s.f., spiral filament 



s.g., stratum granulosum 



s.m., shell membrane 



sp., spinal cord 



S.p., Seesel 's pouch 



s.r., sinus rhomboidalis 



st., stomach 



s.t., sinus terminalis 



s.v., sinus venosus 



t., tingierbare Korner 



th., thymus 



thy., thyroid 



u., uterus 



u.o., urogenital orifice 



ur., ureter 



U.S., urinogenital sinus 



u.s.g., utriculosaccular groove 



utric., utriculus 



u.v., umbilical vein 



v., ventricle 



v.a., ventral aorta 



v.c.f., vestibulocochlear fossa 



v.ch., vascular chorion 



v.c., ventral concavity 



v.p., ventral pouch 



W.d., wolfiian duct 



x., X-chromosome 



y., Y-chromosome 



y.b., yolk balls 



y.g., yolk granules 



y.s., yolk sac 



z., zona pellucida 



.-J-.. r ";. '-'/.' ?-?i ' ' .V- -'*-' Tfilt X^ * 



&/K^%- 



^fl <&*.: ^ ^S.^nPS 



Fig. 1 Ovarian ova. A, specimen 16270 2 showing first maturation division. 

 B, specimen 16274 showing first polar body and the sub-peripheral distribution 

 of yolk granules. 



2 This is the catalogue number of this specimen in The Wistar Institute embryo- 

 logical collection. Throughout this book such numbers are recorded for the con- 

 venience of any investigators who may wish to examine the original material. 



