This material is from the 4th edition of The Zebrafish Book. The 5th edition is available in print and within the ZFIN Protocol Wiki. |
Period | Stage | Begins | Developmental Landmarks | Anatomy |
Zygote (0 - 0.75 h) | 1-cell | 0.00 h | Cytoplasm streams toward animal pole to form blastodisc | Browse AO |
Cleavage (0.75 - 2.25 h) |
2-cell | 0.75 h | Partial cleavage | Browse AO |
4-cell | 1.00 h | 2 X 2 array of blastomeres | Browse AO | |
8-cell | 1.25 h | 2 X 4 array of blastomeres | Browse AO | |
16-cell | 1.50 h | 4 X 4 array of blastomeres | Browse AO | |
32-cell | 1.75 h | 4 X 8 array of blastomeres | Browse AO | |
64-cell | 2.00 h | 3 regular tiers of blastomeres | Browse AO | |
Blastula (2.25 - 5.25 h) |
128-cell | 2.25 h | 5 blastomere tiers; cleavage planes irregular | Browse AO |
256-cell | 2.50 h | 7 blastomere tiers | Browse AO | |
512-cell | 2.75 h | 9 blastomere tiers; YSL forms | Browse AO | |
1k-cell | 3.00 h | 11 blastomere tiers; single row of YSL nuclei; asynchronous cell cycle | Browse AO | |
High | 3.33 h | > 11 blastomere tiers; blastodisc flattening begins; YSL nuclei in two rows | Browse AO | |
Oblong | 3.66 h | Blastodisc flattening; multiple rows of YSL nuclei | Browse AO | |
Sphere | 4.00 h | Spherical shape; flat border between blastodisc and yolk | Browse AO | |
Dome | 4.33 h | Yolk cell bulging toward animal pole as epiboly begins | Browse AO | |
30%-epiboly | 4.66 h | Blastoderm an inverted cup of uniform thickness | Browse AO | |
Gastrula (5.25 - 10.33 h) |
50%-epiboly | 5.25 h | Blastoderm remains of uniform thickness | Browse AO |
Germ-ring | 5.66 h | Germ ring visible from animal pole; 50%-epiboly | Browse AO | |
Shield | 6.00 h | Embryonic shield visible from animal pole; 50%-epiboly | Browse AO | |
75%-epiboly | 8.00 h | Dorsal side distinctly thicker; epiblast, hypoblast, evacuation zone visible | Browse AO | |
90%-epiboly | 9.00 h | Axis and neural plate; brain and notochord rudiments | Browse AO | |
Bud | 10.00 h | Tail bud prominent; early polster; 100%-epiboly | Browse AO | |
Segmentation (10.33 - 24 h) |
1-4 somites | 10.33 h | First somite furrow | Browse AO |
5-9 somites | 11.66 h | Polster prominent; optic vesicle, Kupffer's vesicle, neural keel | Browse AO | |
10-13 somites | 14 h | Pronephros forms | Browse AO | |
14-19 somites | 16 h | EL (embryo length) = 0.9 mm; otic placode, brain neuromeres | Browse AO | |
20-25 somites | 19 h | EL = 1.4 mm; lens, otic vesicle, hindbrain neuromeres | Browse AO | |
26+ somites | 22 h | EL = 1.6 mm; blood islands, otoliths, midbrain-hindbrain boundary | Browse AO | |
Pharyngula (24 - 48 h) |
Prim-5 | 24 h | EL = 1.9 mm; early pigmentation, heartbeat | Browse AO |
Prim-15 | 30 h | EL = 2.5 mm; early touch reflex, retina pigmented | Browse AO | |
Prim-25 | 36 h | EL = 2.7 mm; early motility, tail pigmentation | Browse AO | |
High-pec | 42 h | EL = 2.9 mm; rudiments of pectoral fins | Browse AO | |
Hatching (48 - 72 h) |
Long-pec | 48 h | EL = 3.1 mm; elongated pectoral fin buds | Browse AO |
Pec-fin | 60 h | EL = 3.3 mm; pectoral fin blades | Browse AO | |
Larval | Protruding-mouth | 72 h | 3.5 mm total body length | Browse AO |
Day 4 | 96 h | 3.7 mm total body length | Browse AO | |
Day 5 | 120 h | 3.9 mm total body length; 6 teeth | Browse AO | |
Day 6 | 144 h | 4.2 mm total body length | Browse AO | |
Days 7-13 | 168 h | 4.5 mm total body length; 8 teeth | Browse AO | |
Days 14-20 | 14 d | 6.2 mm total body length; 10 teeth | Browse AO | |
Days 21-29 | 21 d | 7.8 mm total body length | Browse AO | |
Juvenile | Days 30-44 | 30 d | 10 mm total body length; adult fins/pigment | Browse AO |
Days 45-89 | 45 d | 14 mm total body length; 12 teeth | Browse AO | |
Adult (90 d - 2 y) | 90 d | Breeding adult | Browse AO | |
Unknown | Stage yet to be determined. |