Axolotls et cie, reproduction et ponte

REPRODUCTION - PONTE

Nathalie C

Spawning / Breeding

In addition to this, you will need to know more about it.

Axolotls reach reproductive maturity between 8 months and several years, depending on the frequency and quality of food as well as water temperature and general maintenance conditions.
The axolotls are ready around their 18 cm. Females often a month or two after males.

Breeding - Methods

In general the breeding season would be from December to June. Obviously we can raise juveniles all year round but at the start of the season the success will be more important. As the days are shorter and cooler, axolotls will still tend to breed during the winter.
One method would be to induce reproduction by separating male and female for a few weeks and then reintroducing them both into an aquarium 4 degrees cooler, the heat shock would stimulate the male.
This method is to be attempted only in the event of the impossibility of the male to release spermatophores to help the damsel in distress to expel her eggs and thus avoid death by retention of eggs (so if the female is huge and for a while), otherwise no interest in bothering them like this, let nature do it!
Reproduction occurs naturally if your axolotls are kept in good conditions. And that without exhausting your females or males.

In the facts :
The female gets bigger, filling herself with eggs that have not yet been fertilized (sometimes this is not even noticeable, I have the case of a female in which it is never visible, she remains slender all the time).
The male feeling that the eggs of the latter have reached maturity will begin a courtship which you will not necessarily attend because it can take place late at night or early in the morning. He lifts the female, twirls her around it can seem violent even sometimes, but it is not, he thus stimulates the female and also prepares to sow spermatophores (small translucent cones of jelly with a tiny triangle at the tip. white, below in photo).

Once the spermatophores have been deposited everywhere in the aquarium, the female will inseminate herself by taking the white part using her cloaca. She will fertilize her eggs that she can lay between 24 hours and 3 weeks later! And yes the lapse of time is also very random. To do this, it clings to plants and "sows" its eggs there in long strings. ( See video1 ) ( video2 ).

Female, short and more pointed cloaca

Male, long cloaca

Nathalie C

evolution jour apres jour oeufs axolotls

Nathalie C

Eggs from an albino mother = always white

EGG

Cleavage: from egg to embryo

First cleavage shots.
About 1h30 after the penetration of the spermatozoon, the first plane of cleavage resulting from the first mitosis appears. It divides the cell-egg into two first cells of the same size or blastomeres. We speak of total and equal segmentation.
Three quarters of an hour later, the 2 nd cleavage plane appears perpendicular to the first and divides the egg into 4 cells of the same volume.

From stages 2 to 4 cells. In these embryos, the dorsoventral polarization remains clearly visible thanks to the difference in pigmentation. The first cleavage plane passes through the median plane and divides the egg into two identical cells with regard to pigmentation. At the 4-cell stage, the two light-colored dorsal blastomeres can be clearly distinguished, as well as the two darker ventral blastomers.

Morula-Blastula
Subsequently, the cleavage planes follow one another rapidly. The young embryo first becomes a morula by resemblance to a small blackberry (fig. 14).

From stage 8 to 128 cells, the embryo takes the form of a small blackberry. This is the morula stage. The difference in dorsoventral pigmentation is still noticeable.

At the end of the cleavage period, the embryo is a blastula (fig. 15).

Blastula stage seen through the animal pole.

A web gallery brings together the different stages of cleavage of the xenopus egg ( see animation ).

The blastula comprises several thousand cells and is subdivided into three regions with different destinies (fig. 16). These three major regions can be transferred to a meridian histological section (passing through the animal pole-vegetative pole axis):
- the animal skullcap, made up of cells from the region of the animal pole which constitute the ectodermal tissues at the origin of the epidermis and the neuroderm.
- the marginal zone, at the origin of mesodermal tissues such as the skeleton, muscles, kidneys, heart, etc.
The animal cap and the marginal zone are subdivisions of the animal hemisphere.

- The vegetative hemisphere is at the origin of the tissues of the digestive tract and the annexed glands.

Figure 16. Diagram of a xenopus blastula (A) from histological sections made in the animal (B) and vegetative (E) hemispheres. On the details (C and D), the cellular boundaries underlined in red highlight the difference in size between the micromers of the animal pole and the macromers of the vegetative pole. At the level of the animal pole, the embryonic epithelium is tristratified. HA: Animal Hemisphere, HV: Vegetative Hemisphere.

In the center of the animal hemisphere, we notice the segmentation cavity or blastocoele (Fig. 16), which can be highlighted by a dissection of the embryo (Fig. 17).

Figure 17. Blastula opened by the animal hemisphere showing the floor of the blastocoele. To view the dissection, choose the sequence below.
Reduced file size: 328 KB
Full sequence: 3.1 MB

We notice that the cells of the animal polar region are small (micromers) as opposed to the large cells of the vegetative hemisphere (macromers). The reason for this asymmetry is due to the presence of nutrient reserves or yolk, stored in the form of larger grains or platelets at the vegetative pole than at the animal pole.
In Figure 16, the focus is also on the organization of the embryonic epithelium of the animal pole. In xenopus, this is formed by three irregular layers of cells. This detail is important because it is common in anurans unlike urodeles where the ceiling of the blastocele is made up of two layers of cells. These differences are not without consequences on the rest of the development, in particular during the implementation of the cellular movements which will occur at the following stage: gastrulation.