Cynops cyanurus Embryonic Development

A photo series by Ferenc Bády

In 2013 I decided to document the embryonic development of this species in as much detail as I can. I wanted to take photos at least once a day until the larva started eating. On the morning of April 6 I collected some freshly laid eggs from the tank where one of the females was housed temporarily. The egg shown on the first photo seemed infertile, so I chose another one. The rest of the images show the same individual. It was stored in a separate dish, and I changed the water about twice a week. For taking photos I placed it into a black film box cap. On the day 18, due to a little disturbance while setting it up for taking the photo, the weakened egg shell was torn and the larva hatched. After this it was put in a transparent plastic box for each photograph.

Cynops cyanurus embryo Day 1, shortly after laying.
Cynops cyanurus embryo A few hours later, after the first cell division. The embryo consists of two cells.
Cynops cyanurus embryo In the evening. The third cell division has just started along the horizontal plain.
Cynops cyanurus embryo Two hours later the embryo has reached the morula stage.
Cynops cyanurus embryo Day 2, in the morning. Early blastula stage.
Cynops cyanurus embryo Day 2, in the evening. A more advanced blastula.
Cynops cyanurus embryo Day 3, in the morning (dorsolateral view). The mass of small, quickly-dividing, yolk-free cells in the animal pole started to expand over the larger, yolk-rich cells of the vegetal pole (margin shown by arrows). The layer created by the former cells will form the ectoderm and mesoderm, while the latter ones will create the endoderm.
Cynops cyanurus embryo Day 3, in the evening (ventral view). The above mentioned process in a more advanced stage.
Cynops cyanurus embryo Day 4, in the morning (ventral view). Gastrulation is in process: ectodermal cells are migrating into the blastocoel through the blastopore (arrow) to create the mesoderm.
Cynops cyanurus embryo Day 4, in the afternoon. The neural plate appears and starts to separate from the ectoderm (anterior end is upper left).
Cynops cyanurus embryo Day 4, in the evening. Neural plate is folding into a tube.
Cynops cyanurus embryo Day 5, in the morning. The anterior end of the neural tube is transforming into the brain, and the head is starting to develop (on the left).
Cynops cyanurus embryo Day 6, in the morning. Primordium of the inner ear (arrow) and tail bud are visible.
Cynops cyanurus embryo Day 7, in the morning. Body is becoming elongated, and the tail bud is longer too.
Cynops cyanurus embryo Day 8, in the morning. The first pigment cells and gill buds appear.
Cynops cyanurus embryo Day 9, in the evening. Tail fin appears. All of the subsequent photos were taken in the evening.
Cynops cyanurus embryo Day 10. Fins are higher, tail is longer.
Cynops cyanurus embryo Day 11.
Cynops cyanurus embryo Day 12.
Cynops cyanurus embryo Day 13.
Cynops cyanurus embryo Day 14.
Cynops cyanurus embryo Day 15. Eye and balancer are visible.
Cynops cyanurus embryo Day 16.
Cynops cyanurus embryo Day 17.
Cynops cyanurus embryo Day 18. Larva hatched.
Cynops cyanurus embryo Day 19. Developing forelimb is visible (arrow).
Cynops cyanurus embryo Day 20.
Cynops cyanurus embryo Day 21.
Cynops cyanurus embryo Day 22. Hind limb buds are visible (arrow).
Cynops cyanurus embryo Day 23. Most of the yolk has absorbed, and the next day the larva started eating.

 

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