Table of Stages

 

Stages in Amphibian Development
Stage Description

Rana sylvaticus
in hours at
18°C

 Rana pipiens
in hours at
18°C

Ambystoma
punctatum
18°C
1 Unfertilized 0 0 0
2 Gray crescent 1 1
3 2-Cell 2.5 3.5 15.5 hrs
4 4-Cell 3+ 4.5 21 hrs
5 8-Cell 4.5 5.7 25 hrs
6 16-Cell 5+ 6.5 27 hrs
7 32-Cell 6 7.5 31 hrs
8 Mid-cleavage 12 16 2 days
9 Late cleavage 16 21
10 Early gastrula, dorsal lip forming 19 26 4 days
11 Mid-gastrula 24 34 4.5 days
12 Late gastrula 28 42 5 days
13 Neural plate 36 50 6 days
14 Neural folds 40 62 7 days
15 Rotation 45 67
16 Neural tube 50 72
17 Tailbud 58 84
18 Muscular response 65 96
19 Heartbeat 75 118
20 Gill circulation, hatching 90 140
Sources: After Rugh, 1948. Experimental Embryology: A Manual of Techniques and Procedures. Burgess Publishing, Minneapolis, MN.