<body>
<h2 align="center">Zebrafish Developmental
Staging Series</h2>
<p>Embryonic stages are modified from <a
href="stages.html">Kimmel et al., 1995.
Developmental
Dynamics 203:253-310</a>. Copyright ©1995 Wiley-Liss, Inc.
Reprinted only
by permission of Wiley-Liss, a subsidiary of John Wiley & Sons,
Inc.</p>
<p>Select a stage name below to get a detailed
description and images. You can
also browse the
zebrafish <a href="/action/ontology/search">Anatomical
Ontology</a> (AO) to show anatomical terms that are present at
that stage.</p>
<p>(h = hours of development at
28.5°C)</p>
<table width="100%" border="0"
cellspacing="0" cellpadding="5">
<tr>
<td
bgcolor="#cccccc"><strong>Period</strong></td>
<td bgcolor="#cccccc"><strong>Stage</strong></td>
<td nowrap bgcolor="#cccccc"
style="padding-right:15px"><strong>Begins</strong></td>
<td bgcolor="#cccccc"><strong>Developmental
Landmarks</strong></td>
<td
bgcolor="#cccccc"><strong>Anatomy</strong></td>
</tr>
<tr>
<td nowrap class="separator"><strong><a
name="Zygote"
href="zygote.html">Zygote</a></strong>
(0 - 0.75
h)</td>
<td class="separator"><a
href="zygote.html">1-cell</a></td>
<td class="separator">0.00 h</td>
<td class="separator">Cytoplasm streams toward animal
pole to form blastodisc</td>
<td class="separator"><a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-4">Browse
AO</a></td>
</tr>
<tr>
<td rowspan="6" valign="top" class="separator"><strong><a
name="Cleavage"
href="cleave.html">Cleavage</a></strong><br>
(0.75 - 2.25
h)</td>
<td class="stripe"><a
href="cleave_stgs.html#2-cell">2-cell </a></td>
<td class="stripe">0.75 h</td>
<td class="stripe">Partial cleavage</td>
<td class="stripe"> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-15">Browse
AO</a></td>
</tr>
<tr>
<td><a
href="cleave_stgs.html#4-cell">4-cell</a></td>
<td>1.00 h</td>
<td>2 X 2 array of blastomeres</td>
<td><a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-11">Browse
AO</a></td>
</tr>
<tr>
<td class="stripe"><a
href="cleave_stgs.html#8-cell">8-cell</a></td>
<td class="stripe">1.25 h</td>
<td class="stripe">2 X 4 array of blastomeres</td>
<td class="stripe"> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-33">Browse
AO</a></td>
</tr>
<tr>
<td><a href="cleave_stgs.html#16-cell">16-cell</a></td>
<td>1.50 h</td>
<td>4 X 4 array of blastomeres</td>
<td><a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-20">Browse
AO</a></td>
</tr>
<tr>
<td class="stripe"><a
href="cleave_stgs.html#32-cell">32-cell</a></td>
<td class="stripe">1.75 h</td>
<td class="stripe">4 X 8 array of blastomeres</td>
<td class="stripe"> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-25">Browse
AO</a></td>
</tr>
<tr>
<td class="separator"><a
href="cleave_stgs.html#64-cell">64-cell</a></td>
<td class="separator">2.00 h</td>
<td class="separator">3 regular tiers of
blastomeres</td>
<td class="separator"><a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-28">Browse
AO</a></td>
</tr>
<tr>
<td rowspan="9" valign="top"
class="separator"><strong><a name="Blastula"
href="blast.html">Blastula</a></strong><br>
(2.25 - 5.25
h)</td>
<td class="stripe"><a
href="blast_stgs.html#128-cell">128-cell</a></td>
<td class="stripe">2.25 h</td>
<td class="stripe">5 blastomere tiers; cleavage planes
irregular</td>
<td class="stripe"> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-7">Browse
AO</a></td>
</tr>
<tr>
<td><a
href="blast_stgs.html#256-cell">256-cell</a></td>
<td>2.50 h</td>
<td>7 blastomere tiers</td>
<td><a href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-1">Browse
AO</a></td>
</tr>
<tr>
<td class="stripe"><a
href="blast_stgs.html#512-cell">512-cell</a></td>
<td class="stripe">2.75 h</td>
<td class="stripe">9 blastomere tiers; YSL
forms</td>
<td class="stripe"> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-14">Browse
AO</a></td>
</tr>
<tr>
<td><a
href="blast_stgs.html#1k-cell">1k-cell</a></td>
<td>3.00 h</td>
<td>11 blastomere tiers; single row of YSL nuclei; asynchronous
cell cycle
</td>
<td><a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-22">Browse
AO</a></td>
</tr>
<tr>
<td class="stripe"><a
href="blast_stgs.html#High">High</a></td>
<td class="stripe">3.33 h</td>
<td class="stripe">> 11 blastomere tiers;
blastodisc flattening begins;
YSL nuclei in
two rows</td>
<td class="stripe"> <a href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-27">Browse
AO</a></td>
</tr>
<tr>
<td><a
href="blast_stgs.html#Oblong">Oblong</a></td>
<td>3.66 h</td>
<td>Blastodisc flattening; multiple rows of YSL nuclei</td>
<td><a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-24">Browse
AO</a></td>
</tr>
<tr>
<td class="stripe"><a
href="blast_stgs.html#Sphere">Sphere</a></td>
<td class="stripe">4.00 h</td>
<td class="stripe">Spherical shape; flat border between
blastodisc and yolk</td>
<td class="stripe"> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-21">Browse
AO</a></td>
</tr>
<tr>
<td><a href="blast_stgs.html#Dome">Dome</a></td>
<td>4.33 h</td>
<td>Yolk cell bulging toward animal pole as epiboly
begins</td>
<td><a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-19">Browse
AO</a></td>
</tr>
<tr>
<td bgcolor="#eeeeee" class="separator"><a
href="blast_stgs.html#30%-epiboly">30%-epiboly</a></td>
<td bgcolor="#eeeeee" class="separator">4.66
h</td>
<td bgcolor="#eeeeee"
class="separator">Blastoderm an inverted cup of uniform
thickness</td>
<td bgcolor="#eeeeee" class="separator"> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-17">Browse
AO</a></td>
</tr>
<tr>
<td rowspan="6" valign="top"
class="separator"><strong><a name="Gastrula"
href="gast.html">Gastrula</a></strong><br>
(5.25 - 10.33
h)</td>
<td><a
href="gast_stgs.html#50%-epiboly">50%-epiboly</a></td>
<td>5.25 h</td>
<td>Blastoderm remains of uniform thickness</td>
<td><a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-6">Browse
AO</a></td>
</tr>
<tr>
<td class="stripe"><a
href="gast_stgs.html#Germ-ring">Germ-ring</a></td>
<td class="stripe">5.66 h</td>
<td class="stripe">Germ ring visible from animal pole;
50%-epiboly</td>
<td class="stripe"> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-3">Browse
AO</a></td>
</tr>
<tr>
<td><a href="gast_stgs.html#Shield">Shield</a></td>
<td>6.00 h</td>
<td>Embryonic shield visible from animal pole;
50%-epiboly</td>
<td><a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-2">Browse
AO</a></td>
</tr>
<tr>
<td class="stripe"><a
href="gast_stgs.html#75%-epiboly">75%-epiboly</a></td>
<td class="stripe">8.00 h</td>
<td class="stripe">Dorsal side distinctly thicker;
epiblast, hypoblast, evacuation
zone
visible</td>
<td class="stripe"> <a href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-18">Browse
AO</a></td>
</tr>
<tr>
<td><a
href="gast_stgs.html#90%-epiboly">90%-epiboly</a></td>
<td>9.00 h</td>
<td>Axis and neural plate; brain and notochord
rudiments</td>
<td><a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-29">Browse
AO</a></td>
</tr>
<tr>
<td bgcolor="#eeeeee" class="separator"><a
href="gast_stgs.html#Bud">Bud</a></td>
<td bgcolor="#eeeeee" class="separator">10.00
h</td>
<td bgcolor="#eeeeee" class="separator">Tail
bud prominent; early polster;
100%-epiboly</td>
<td bgcolor="#eeeeee" class="separator"> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-12">Browse
AO</a></td>
</tr>
<tr>
<td rowspan="6" valign="top"
class="separator"><strong><a
name="Segmentation"
href="seg.html">Segmentation</a></strong><br>
(10.33 - 24
h)</td>
<td><a href="seg_stgs.html#1-somite">1-4
somites</a></td>
<td>10.33 h</td>
<td>First somite furrow</td>
<td><a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-23">Browse
AO</a></td>
</tr>
<tr>
<td class="stripe"><a
href="seg_stgs.html#5-somite">5-9 somites</a></td>
<td class="stripe">11.66 h</td>
<td class="stripe">Polster prominent; optic vesicle,
Kupffer's vesicle, neural
keel</td>
<td class="stripe"> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-5">Browse
AO</a></td>
</tr>
<tr>
<td><a href="seg_stgs.html#10-somite">10-13
somites</a></td>
<td>14 h</td>
<td>Pronephros forms</td>
<td><a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-020626-1">Browse
AO</a></td>
</tr>
<tr>
<td class="stripe"><a
href="seg_stgs.html#14-somite">14-19 somites</a></td>
<td class="stripe">16 h</td>
<td class="stripe">EL (embryo length) = 0.9 mm; otic
placode, brain neuromeres</td>
<td class="stripe"> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-30">Browse
AO</a></td>
</tr>
<tr>
<td><a href="seg_stgs.html#20-somite">20-25
somites</a></td>
<td>19 h</td>
<td>EL = 1.4 mm; lens, otic vesicle, hindbrain
neuromeres</td>
<td><a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-16">Browse
AO</a></td>
</tr>
<tr>
<td bgcolor="#eeeeee" class="separator"><a
href="seg_stgs.html#26-somite">26+
somites</a></td>
<td bgcolor="#eeeeee" class="separator">22
h</td>
<td bgcolor="#eeeeee" class="separator">EL =
1.6 mm; blood islands, otoliths,
midbrain-hindbrain boundary</td>
<td bgcolor="#eeeeee" class="separator"> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-34">Browse
AO</a></td>
</tr>
<tr>
<td rowspan="4" valign="top" class="separator"><strong><a
name="Pharyngula"
href="phar.html">Pharyngula</a></strong><br>
(24 - 48
h)</td>
<td><a
href="phar_stgs.html#Prim-5">Prim-5</a></td>
<td>24 h</td>
<td>EL = 1.9 mm; early pigmentation, heartbeat</td>
<td><a href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-10">Browse
AO</a></td>
</tr>
<tr>
<td class="stripe"><a
href="phar_stgs.html#Prim-15">Prim-15</a></td>
<td class="stripe">30 h</td>
<td class="stripe">EL = 2.5 mm; early touch reflex,
retina pigmented</td>
<td class="stripe"> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-32">Browse
AO</a></td>
</tr>
<tr>
<td><a
href="phar_stgs.html#Prim-25">Prim-25</a></td>
<td>36 h</td>
<td>EL = 2.7 mm; early motility, tail pigmentation</td>
<td><a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-13">Browse
AO</a></td>
</tr>
<tr>
<td bgcolor="#eeeeee" class="separator"><a
href="phar_stgs.html#High-pec">High-pec</a></td>
<td bgcolor="#eeeeee" class="separator">42
h</td>
<td bgcolor="#eeeeee" class="separator">EL =
2.9 mm; rudiments of pectoral
fins</td>
<td bgcolor="#eeeeee" class="separator"> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-31">Browse
AO</a></td>
</tr>
<tr>
<td rowspan="2" valign="top"
class="separator"><strong><a name="Hatching"
href="hatch.html">Hatching</a></strong><br>
(48 - 72
h)</td>
<td><a
href="hatch_stgs.html#Long-pec">Long-pec</a></td>
<td>48 h</td>
<td>EL = 3.1 mm; elongated pectoral fin buds</td>
<td><a href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-9">Browse
AO</a></td>
</tr>
<tr>
<td bgcolor="#eeeeee" class="separator"><a
href="hatch_stgs.html#Pec-fin">Pec-fin</a></td>
<td bgcolor="#eeeeee" class="separator">60
h</td>
<td bgcolor="#eeeeee" class="separator">EL =
3.3 mm; pectoral fin blades</td>
<td bgcolor="#eeeeee" class="separator"> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-26">Browse
AO</a></td>
</tr>
<tr>
<td rowspan="7" valign="top"
class="separator"><strong><a name="Larval"
href="larv_stgs.html">Larval</a></strong></td>
<td nowrap><a
href="larv_stgs.html">Protruding-mouth</a></td>
<td>72 h</td>
<td>3.5 mm total body length</td>
<td> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-8">Browse
AO</a></td>
</tr>
<tr>
<td class="stripe">Day 4</td>
<td class="stripe">96 h</td>
<td class="stripe">3.7 mm total body length</td>
<td class="stripe"> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-35">Browse
AO</a></td>
</tr>
<tr>
<td>Day 5</td>
<td>120 h</td>
<td>3.9 mm total body length; 6 teeth</td>
<td> <a href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-36">Browse
AO</a></td>
</tr>
<tr>
<td class="stripe">Day 6</td>
<td class="stripe">144 h</td>
<td class="stripe">4.2 mm total body length</td>
<td class="stripe"> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-37">Browse
AO</a></td>
</tr>
<tr>
<td>Days 7-13</td>
<td>168 h</td>
<td>4.5 mm total body length; 8 teeth</td>
<td> <a href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-47">Browse
AO</a></td>
</tr>
<tr>
<td class="stripe">Days 14-20</td>
<td class="stripe">14 d</td>
<td class="stripe">6.2 mm total body length; 10
teeth</td>
<td class="stripe"> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-48">Browse
AO</a></td>
</tr>
<tr>
<td class="separator">Days 21-29</td>
<td class="separator">21 d</td>
<td class="separator">7.8 mm total body
length</td>
<td class="separator"> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-49">Browse
AO</a></td>
</tr>
<tr>
<td rowspan="2" valign="top" class="separator"><strong><a
name="Juvenile">Juvenile</a></strong></td>
<td class="stripe">Days 30-44</td>
<td class="stripe">30 d</td>
<td class="stripe">10 mm total body length; adult
fins/pigment</td>
<td class="stripe"> <a href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-51">Browse
AO</a></td>
</tr>
<tr>
<td class="separator">Days 45-89</td>
<td class="separator">45 d</td>
<td class="separator">14 mm total body length; 12
teeth</td>
<td class="separator"> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-52">Browse
AO</a></td>
</tr>
<tr>
<td nowrap class="separator"><strong><a
name="Adult">Adult</a></strong> (90
d - 2
y)</td>
<td bgcolor="#eeeeee"
class="separator"> </td>
<td bgcolor="#eeeeee" class="separator">90
d</td>
<td bgcolor="#eeeeee"
class="separator">Breeding adult</td>
<td bgcolor="#eeeeee" class="separator"> <a
href="/action/ontology/show-anatomy-terms-by-stage?stage.zdbID=ZDB-STAGE-010723-39">Browse
AO</a></td>
</tr>
<tr>
<td class="separator"><strong><a
name="Unknown">Unknown</a></strong></td>
<td colspan="4" class="separator">Stage yet to
be determined.</td>
</tr>
</table>
</body>