Our Japanese Medaka Egg!!! Baby Puddles Yoko--*


Term Dictionary!!!

Day One


The little circles in the yolk are oil droplets.

We predict that our egg, Puddles, is in stage 17, which is 23 hours old. This stage is called the Eary Neurula because the central nervous system appears as a delicate streak of cells that are in the middle of the shield. Also, 4/5 of its yolk is covered by the extraembryonic empithelia. We predict that it will hatch on the 13th day.

Day Two

The little hair-like structures branching off the Vitelline Membrane are the Vitelline Veins.
All of the structures appear very similar compared to the stage before (stage 17).

We believe the stage of our fish is in stage 19, 29 hours; this stage is the "Blastopore" Closed and Optic Vesicle. During this stage, the blastopore closes and the tail begins to terminate. Also, the rudimentary optic vesicle is formed and mesoderm has located itself in the future anterior somites (divisions). We believe it will hatch on the 13th day.

Day Three

We believe the stage of our fish is in stage 23, 46 hours, because it is the Heartbeat stage.
Every 60 seconds its heart beat 37 times.
During this stage, there is no circulation yet there is blood coming together on the yolk. Also, the head and tail have begun to lift off the yolk sac and otocysts without otoliths are defined. Lastly, around 15 somites are formed and a somite is a division in an animal's body. We believe it will hatch on the 12th day because of the newly identified structures.

P.S.- Puddles grew about 32 microns since day one (in two days).

Day Four

We believe that our fish is in stage 28 or 74 hours and his heart beats 79 times per minute. The cardinal vein begins to change in this stage because it becomes a wide, flat arc near the yolk's center and there are about 30 somites (refer to term dictionary at bottom). We still belive it will hatch on the 12th day.

Day Eight (counting weekend)

We believe our egg is now in stage 29 which is 89 hours. In this stage, the cardinal and vitelline veins take branching paths. Also, the retina can be seen through and the tail may be able to move the whole animal. Puddle's heart beats 110 times a minute. We belive it will hatch on the 12th day.

Day Nine


We believe our egg in stage 28 which means it is about 74 hours old. In this stage, the cardinal vein flows in a wide and flat arc near the center of the yolk sphere. Also, there is no current branching, but the tail has lengthened the embryon to around 1.7mm (30 somites). Puddles heartbeat was 122 beats a minute. We belive it will hatch on the 12th day.

Day Ten

We believe that our egg is in stage 29 which means that it is about 84 hour old. In this stage, the cardinal vein and the vitelline vein flow in a curvy path rather and branch off rather than flow right through the middle of the yolk. Also the retina becomes more visible, and a set of pectoral fins began to appear. When we were viewing the egg through the moticam, we noticed the tail every once in a while moving the egg slightly which is something that happens in this stage. Puddles heartbeat was 131 beats a minute today. We belive our egg will still hatch on the 12th day.

Day Eleven

Our egg is in stage 36 which is 264 hours and HATCHING WOOOO!!! Because our egg hatched on the 11th day, it had a larger yolk mass than others which is about 4-4.5 mm long. By this point, there are about 30 somites, the head extends, and the mouth opens. They are even coordinated with swimming and breathing movements and the bladder is about the size of the oil globule. We were one day off on guessing which day puddles was supposed to hatch.

Term Dictionary!!!

Somite- A division in an animal's body

Embryonic Shield/Disk- A platelike mass of cells in the blatocyst from which certain embryos develop

Otocysts- a fluid containing organ inside of invertabrates

Otoliths- a sensory organ that is for balance and hearing in fish

Vitelline Membrane- the outer surface of the plasma membrane of an ovum

Vitelline Veins- two extensions of the early embryo heart that spread in between the mesoderm and endoderm

Yolk- the first site of blood formation and food source

Extraembryonic Epithelia- a structure that gradually begins to cover the yolk inside of the young embryo

Cardinal Vein- any of the four veins running aside the vertabral column

Vertabral column- the backbone or spine

Retina- This is the inner part of the eyeball.

We will add more as we find more words to define! : )