Implantation, placentation and post-implantation embryonic

development

Timing of implantation

• Marmoset 11-12 days• Rhesus 6-7 days• Human 6-7 days• Mouse 6 days

Marmoset implantation

• Implantation day—11-12 post- ovulation

Marmoset twin early implantation site

From Moore et al. 1985

A

B

Stages of placentation

Patterns of twinning

MarmosetMarmoset

7 8 9

10 11

Primitive Streak to Limb Bud Stages

Overview of Embryo StagesCarnegie System

Overview of Embryo StagesCarnegie System

11 12 13 14

Somite/Neurula to Limb Bud Stages

15 16 17 18

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

Time course for embryonic development

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

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

Total pregnancy duration

• Marmoset 144 days • Rhesus 165 days• Baboon 180 days• Human 280 days

Age of sexual maturity

• Marmoset 1.5 years • Rhesus 4.5 years• Baboon 7-10 years• Human 14-16 years

Critical embryonic development stages: formation of the blood system

13

Formation and migration of the primordial germ cells

Stage 14Stage 11

Development of the gonads

13

16

Fusion of placentain marmoset

• Unique feature of Marmoset and Tamarinplacentation 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

• Shared placental circulation results in hemopoietic and bone marrow chimerism

Hearn 1983

At birth

Consequences of sharing fetal circulation

• Fusion of placenta results in blood chimerism and chimerism in other organs.

Are the gametes also chimeric?

Germ line chimerism

This means sharing the cells among 3 or more individuals instead of only 2.

What could be the consequences for the individual?

An additional complication for chimerism – increase in litter size

Possible reason for increased litter size

DPZ CENP Brazil

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?