Table 1 Embryonic development stages of Inimicus japonicus at 21°C
Main stages | Substages | Time (h:min) | Description | Figure |
|---|---|---|---|---|
Zygote | 2-cell stage | 0:23 | First cleavage, blastodisc divided via meridional cleavage to form two equal cells | 1a |
4-cell stage | 0:32 | Second cleavage, dividing the blastodisc into 4 blastomeres | 1b | |
8-cell stage | 0:40 | Third cleavage, 2 x 4 array of blastomeres | 1c | |
16-cell stage | 1:02 | Fourth cleavage, 16 blastomeres can be seen | 1d | |
32-cell stage | 1:35 | Fifth cleavage, 2 regular tiers (horizontal rows) of blastomeres, sometimes in 4 x 8 array | 1e | |
64-cell stage | 2:05 | Sixth cleavage, 64 blastomeres were ranked irregularly | 1f | |
Morula stage | 4:05 | The blastomeres were still distinct but the number of blastomeres can not be counted | 1g | |
Blastula | Early blastula stage | 6:30 | The blastomeres were no longer distinguishable, the blastocoel began to form, and endoderm germ layer appeared | 1h |
Late blastula stage | 9:40 | Epibolic cells increased, the archenteron can be seen, endoderm germ layer invaginated and the ectoderm layer formed | 1i | |
Gastrula | Early gastrula stage | 11:36 | Blastoderm cells begin to spread over the yolk, and blastoderm remains uniform in thickness | 1j |
Mid gastrula stage | 13:45 | Germ ring epiboled 1/2 of yolk sac, embryonic shield visible from animal pole | 1k | |
Late gastrula stage | 15:00 | 75% coverage of the yolk cell by the blastoderm, dorsal side distinctly thicker; epiblast, hypoblast, evacuation zone visible | 1l | |
Neurula | embryoid body formation | 19:47 | The prototype of the neural plate appeared, head part uplifted, yolk plug exposed, pigments on the embryonic shield and yolk sac can be seen | 1m |
Pharyngula | Formation of optic vesicle | 22:23 | On both sides of the head, a pair of kidney-shaped protrusions can be seen | 1n |
Appearance of myomere | 25:46 | Embryoid surrounded the yolk sac, in the center of the embryoid, 8–11 myomeres can be seen. | 1o | |
Muscular effect | 38:35 | Embryo begins to spin frequently, heart beat 70-75/min | 1p | |
Pre-hatching stage | 42:45 | The embryo shows conspicuous muscular contractions | 1q | |
Hatching | newly hatched larva | 44:05 | General transparent, floating on the water surface | 1r |