460 



MOUSE EMBRYO 



THE MOUSE EMBRYO: 6.5 TO 18.5 DAYS POST-CONCEPTION 



Fig. 47 - Paired uteri of mouse at 6. 5 days showing 11 im- 

 plantation sites. Note ovaries at upper end. and 

 coiled oviducts. 



Fig. 4S - Genital system of pregnont mouse at 7. 5 days 

 with 11 implantations. 



Fig. 49 - Same at 8. 5 days. Note enlarging embryonic 

 masses. 



Fig. 50 - Same at 9. 5 days. Note only two implantations 

 on left. 



Fig. 51 - Same at 10. 5 days with embryos on left exposed; 

 14 implantations. 



Fig. 52 - Enlarged view of embryos in situ at 10. 5 days. 

 Note very vascular amnion covering lowermost 

 embryo. 



Fig. 53 - Exposed mouse embryos at 11.5 days. Note 

 appendage development. 



Fig. 54 - Implantation sites of left uterus at 12. 5 days. 

 Right side not shown. 



Fig. 55 - Uteri at 13. 5 days with four embryos partially 

 exposed. Next to lowest implantation on right 

 is probably a resorption site. 



Fig. 56 - Entire litter of six (only) at 16. 5 days liberated 

 from their uterine sites but still attached by 

 umbilical cords to placentae. Development such 

 that they should be regarded as fetuses. 



Fig. 57 - Sagittal section or mouse fetus at 15. 5 days gesto- 

 tation. Note particularly the hepatic vein to the 

 sinus venosus; the vertebrae; and the development 

 of the cerebral vesicles. 



Fig. 58 - Sagittal section of entire fetus at 16. 5 days gesta- 

 tion, showing brain and cord; aortic arch from 

 ventricle; and prominent tongue muscles. 



Fig. 59 - Sagittal section of mouse fetus at 17.5 days. 



Note well differentiation of the brain and spinal 

 cord; heart; and viscera. 



Fig. 60- Sagittal section of mouse embryo at 18. 5 days. 



Fig. 61 - Same as Fig. 60 but at different level. 



MOUSE EMBRYOS: 1 1. 5 to 17.5 DAYS GESTATION 



Prawings by R. van Dyke, from Rugh's "Embryology", 

 Harcourt, Brace G Co., 1963) 



