ABSTRACT
In 1975, Hendrickx and Sawyer 14 published an atlas of rhesus monkey embryos arranged in Carnegie stages 1 to 23. The material illustrated was taken from Heuser and Streeter 15 and the California Primate Research Center. Gribnau and Geijsberts 16 described stages 13 to 23 in considerably greater detail. Comparison of stages 1 to 8 human and rhesus monkey embryos is rendered difficult because of their different mode of implantation and placentation, so these early stages will be merely listed ( Table 5). Carnegie Stages 1 To 8 of Rhesus Monkey Embryos
Carnegie stage
Age (days)
Features
1
1
Fertilization
2
2—4
From 2 to 16 cells
3
5—8
Free blastocyst
4
8—10
Attaching blastocyst
5
10—11
Previllous stage
6
12—15
Primitive villi, early primitive streak
7
16—18
Notochordal process
8
19—20
Primitive pit and neurenteric canal
Based on Hendrickx, A. G. and Sawyer, R. H., Embryology of the rhesus monkey, in The Rhesus Monkey, Bourne, G. H., Ed., Academic Press, New York, 1975, 141.