7. Overview of Embryo Stages
Carnegie System
Primitive Streak to Limb Bud Stages
7 8 9
10 11
8. Overview of Embryo Stages
Carnegie System
Somite/Neurula to Limb Bud Stages
11 12 13 14
15 16 17 18
9. Timing of marmoset embryonic
development
• Early limb bud stage (stage 11) GD 50
– 25 days later than human
• From stage 11 to 23 (completion of
organogenesis)
– 30 days duration for both marmoset and
human
11. Total time required to complete
embryonic development
• Marmoset 80 days
(due to 50 days to limb bud stage)
• Rhesus 47 days
• Baboon 47 days
• Human 58 days
12. Time required for fetal development
(from the end of embryonic development
till birth)
• Marmoset 64 days
• Rhesus 118 days
• Baboon 133 days
• Human 222 days
13. Total pregnancy duration
• Marmoset 144 days
• Rhesus 165 days
• Baboon 180 days
• Human 280 days
14. Age of sexual maturity
• Marmoset 1.5 years
• Rhesus 4.5 years
• Baboon 7-10 years
• Human 14-16 years
18. Fusion of placenta
in marmoset
• Unique feature of Marmoset and Tamarin
placentation is fusion and sharing of fetal
circulation between litter mates
• Fusion of the placenta (chorionic membranes)
starts soon after implantation and is completed
before organogenesis
19. At birth
• Shared placental
circulation results in
hemopoietic and
bone marrow
chimerism
Hearn 1983
20. Consequences of sharing fetal
circulation
• Fusion of placenta results in blood
chimerism and chimerism in other organs.
Are the gametes also chimeric?
22. An additional complication for
chimerism – increase in litter size
This means sharing the cells among 3
or more individuals instead of only 2.
What could be the consequences for
the individual?
24. Can we influence litter size and health
with different captive management?
• High weight animals tend to have larger litters
• Can this be a cause of later health problems?
– partially induced by autoimmune disease due to
mixing of cells from 3 or more individuals.
• Could a change in captive management bring
litter size under control and improve health of
the animals?
