Embryonic development of fish

To get into the embryonic development of fish, we must first know some basic concepts of embryology such as the types of eggs and the phases that make up early embryonic development.

We can find different types of eggs , according to how the yolk is distributed and how much it contains.To begin with, we will call the cell resulting from the union of an egg and a sperm and, vitellum, the set of nutritional elements found in inside the egg and will serve as food for the future embryo.

Types of eggs according to the organization of the vitello inside:

Isolecite eggs : the vitello is uniformly distributed throughout the interior of the egg.Typical of poriferous animals, cnidarians, echinoderms, nemertines and mammals.
Telolecitos eggs : the vitello is displaced towards an area of the egg, being opposite to The place where the embryo will develop.Most animals develop from these types of eggs, for example, mollusks, fish, amphibians, reptiles, birds, etc.
Little center eggs : the vitello is surrounded by cytoplasm and, in turn, envelops the nucleus that will give rise to the embryo.It occurs in arthropods.

Types of eggs according to the amount of vitelo:

Oligolecitos eggs : they are small and have little vitello.
Mesolecyte eggs : medium size with a moderate amount of vitello.
Macrolecitos eggs : they are large eggs with a large amount of vitello.

Typical phases of embryonic development

Segmentation : in this phase a series of cell divisions take place that increase the number of cells needed for the second phase.It ends in a state called blastula.
Gastrulacion : there is a reorganization of the blastula cells giving rise to blastoderms (primitive germ layers) that are ectoderm, endoderm and, in some animals, mesoderm.
Differentiation and organogenesis : the tissues and organs will form from the germ layers, the structure of the new individual being fixed.

The temperature is closely related to the incubation time of eggs in fish and their embryonic development (the same occurs in other animal species).Generally there is an optimal temperature range for incubation, which varies by about 8ÂºC.

Eggs incubated within this range will have a higher probability of developing and hatching.Also, those eggs incubated for long periods of time at extreme temperatures ( out of the last range of the pecie) will have a lower probability of hatching and, if they do, born individuals may suffer serious abnormalities .

Now that you know the basic concepts of Embryology, we will enter the embryonic development of the fish.The fish are telolecitic, that is, they come from telolecyte eggs, those that had the vitellas displaced to an area of the egg.

Zygotic phase

The newly fertilized egg remains in zygote status until the first division, the approximate time at which this split occurs depends on the species and the temperature of the medium.In the zebrafish, Danio rerio (fish most used in research), the first segmentation occurs around 40 minutes after fertilization.Although it seems that there are no changes in this period, In the interior of the egg, decisive processes are taking place for further development.

Phase of s egmentation

The egg enters the segmentation phase when the first division of the zygote occurs.In fish, the segmentation is meroblastic, because the division does not completely pass through the egg since it is prevented from vitelus, but rather It is limited to the area where the embryo is located.The first divisions are vertical and horizontal to the embryo, they are very fast and synchronous.They give rise to a mound of cells seated on the vitellus, constituting the discoid blastula.

Phase of gastrulation

During the gastrulation phase there is a rearrangement of the cells of the discoid blastula by morphogenetic movements, that is, the information contained in the nuclei of the different cells already formed, is transcribed so that forces the cells to obtain a new spatial configuration.In the case of fish, this reorganization is called involvement.Also, this stage is characterized by a decrease in the rate of cell division and little or no cell growth.

During involvement, some cells of the discoblastula or discoid blastula migrate to the vitellum, forming a layer on it.This layer will be the endoderm.The layer of cells that remain on the mound will form the ectoderm.At the end of the process , the gastrula will be defined or, in the case of fish, discogastrula with its two primary germ layers or blastoderms, the ectoderm and the endoderm.

Phase of differentiation and organogenesis

DuringIn the phase of differentiation, in fish, the third embryonic layer appears, located between the endoderm and the ectoderm, called the mesoderm.

The endoderm is invaded forming a cavity called archaenteron.The entrance to this cavity will be called blastoporo and will give rise to the anus of the fish.From this point, the cephalic vesicle (encephalon in formation) can be distinguished and, on both sides, the vesiculasopticas (future eyes).Next the cephalic vesicle will form the neural tube and, on either side, the Somites, structures that will eventually form the bones of the spine and ribs, muscles and other organs.

Throughout this phase, each germ layer will eventually produce several organs or tissues, so that:

Ectoderm :

Epidermis and nervous system
Beginning and end of the digestive tract

Mesoderm :

Dermis
Musculature, excretory and reproductive organs
Celoma, peritoneum and circulatory system

Endoderm :

Organs involved in digestion: internal epithelium of the digestive tract and attached glands.
Organs responsible for gas exchange.

Comments

Angora rabbit care

If you are thinking of adopting an Angora rabbit , in This article from Animals and Pets Online we will explain the basic care of these cute bunnies. The Angora rabbit is a variety of the domestic rabbit, so its care is very similar.It is believed that its origins are in Turkey, where they were exploited for their fur. The fur differentiates them and that's why their care is very important.If you don't have time to brush and take care of your Angora rabbit we recommend Be responsible and consider it before taking it home. Basic care of Angora rabbit There are four varieties of Angora rabbit: English Angora rabbit French Angora rabbit Angora rabbit giant Angora saten rabbit Between the different varieties there are differences in size and color of the fur, but in terms of care they do not vary in excess. Everyone needs good food, regular exercise and good care of the fur .With these spots covered our little rabbit will grow strong and healthy. They are...

AIR ANIMALS - Examples and characteristics

Flying is one of the ways animals have to move , but not everyone can do it.To fly it is necessary to have physical characteristics that allow the flight.The human being, through the observation of aerial animals, has taken centuries to create a machine that flies, for example, as a bird. Only a few groups of animals have the real ability to fly, although if we see it from the perspective of the species, most of the animal species that exist on the planet fly, insects.In this article of Animal Expert we will know which are the aerial animals , their characteristics and some examples. What are air animals? Air animals are those that use flight as a mechanism of locomotion.For some animals this is their only way of moving but many others use it as an escape route in the presence of a predator. Certain animals spend the majority of their lives flying, performing all their vital functions in the air: eating, interacting with their environment and living or reproducing.For them, f...

Types of monkeys and their names

Monkeys are primates classified according to scientific jargon in the Platirrinos or monkeys of the new world and the Cercopitecoideos or monkeys of the old world.The hominoids, which would be primates that have no tail, where man enters. Animals such as orangutan, chimpance, gorilla or gibbons also do not enter the scientific classification of monkeys, since the latter, in addition to having a tail, have a more primitive skeleton and are small animals. Then you can see the scientific classification of monkeys in more detail, where you can distinguish two different parvordenes and a total of six families of monkeys, all this in this article of Animals and Pets Online.The different types of monkeys and their names you can see them below: Classification of the Simiiform infraorder To correctly understand everything about the types of monkeys we must detail that there are a total of 6 families of monkeys grouped in 2 different parvordenes. Parvorden Platyrrhini: This in...

Animals with exoskeleton - Names and examples

The body of the largest vertebrate animals is not a mystery to most of people: it is known that it has a skeleton, internal vital organs (heart, brain, etc.), a dermis of variable and organ characteristics through which the five senses are manifested, among other characteristics. However, have you wondered what the invertebrate morphology is like? Then you need to know all about the animals with exoskeleton, names and examples. Don't miss this Animals and Pets Online article! What is the exoskeleton? The exoskeleton is an external structure that covers the body of various animals, including arthropods.It is characterized by being resistant but flexible .This structure It consists of different substances depending on the subfile to which the animal belongs: chitin for insects and fungi, calcium in mollusks and corals or silica in diatoms among other components. In turn, the exoskeleton is formed by three structures : Cuticle : non-cellular layer secreted by the hyp...

Company Animal Names

Names for male and female doberman dogs The Doberman Pinscher is a dog of large size, stylized, elegant, muscular and proportionate.It stands out for its peaceful and friendly character, despite what many people may think due to the unfair fame that this canine breed has acquired throughout Unfortunately, many are the... Names for male white dogs and females Have you ever thought about adopting a white dog? Surely it is! However, you should keep in mind that owning one of these dogs requires a lot of attention to keep the fur clean, although we must say that it will be worth it when you admire the elegant white mantle. If you're thinking... Names for cats in English and their meaning-Males and females Searching for names for cats is a very fun experience and that generates great expectations among all the members of the family unit.If you are also at this time, you are likely to look for names for cats in English and their meaning, a language every time more globalized In this...

Native animals of Chile - Discover the 10 most representative!

Chile is a country of America of the South with varied ecosystems: the Pacific Ocean coast, the rugged and snow-capped mountain range of the Andes, the Atacama desert, the ice of the Antarctic region are some of them.With such different geographical accidents, it is not uncommon for the fauna and flora are also diverse. If you are interested in knowing which species are hidden in these lands, then you cannot miss this article of Animals and Pets Online on native animals of Chile .Keep reading! Animals of the southern zone of Chile: monkey The Dromiciops gliroides , also called mountain monkey or colocolo is a marsupial that inhabits the coastal areas of the Maule region, has a brown coat Of course, bulging eyes and long ears and teeth.It feeds mainly on fruits, seeds and insects.It is a very clever animal with its legs , which allows it to obtain food in an easier way and tree climbing to escape predators.The mountain monkey lives alone, meets in flocks of a maximum of th...

Differences between donkey and donkey

Taxonomy or classification of animals can, in many cases, give rise to numerous doubts, since sometimes we are not able to identify if two different nomenclatures refer to the same animal or if instead it is a species and subspecies, for example. Some Animals are known by similar names but are part of different species, others can instead be called by several clearly different names and still be the same species, therefore, there are multiple cases that can confuse us and need to be clarified./p> Surely on some occasion you have wondered what are the differences between donkey and donkey , and in this article of Animals and Pets Online we answer your questions. What differentiates an ass from a donkey? When we talk about donkeys we can all evoke the image of an animal with characteristic long ears and tail endowed with great fur, which has traditionally been expanded as a pack animal.Well, when we talk about donkeys, although we may not know this fact, we are talking about...

Pneumonia in dogs - Contagion, care and treatment

Surely you've ever heard of pneumonia, a disease that our dogs may also suffer.In this article of Animals and Pets Online we will review their symptomatology so that you can recognize it and thus transfer your dog to the veterinarian, who, as always, will be responsible for confirming the diagnosis and establishing guidelines for proper care and treatment . Keep reading this article from Animals and Pets Online to learn more about pneumonia in dogs, infection, symptoms and treatment You can't miss it! What is pneumonia? Basically, pneumonia is a inflammation of the lungs , caused by a variety of causes ranging from infectious agents, such as bacteria, to parasites, foreign bodies or allergens.classified according to the area of the lung that affect, according to the predominant cell class, the cause and the type of reaction they cause in the lung.It is the veterinarian in charge of refining the diagnosis to be able to apply the most appropriate treatment. The ...

Diclofenac for dogs - Dosage and uses

The diclofenac sodium is the active substance of a a well-known drug and used under the trade name of Voltaren or Voltadol.It is a product that is used to fight pain .Has your veterinarian prescribed it for your dog? Do you have questions about its uses or doses? In this article of Animals and Pets Online we will talk about diclofenac for dogs , how this drug is used in veterinary medicine and what aspects are important to consider for its use As we always insist, this and any other medication can only be administered to a dog by veterinary prescription . Is diclofenac bad for dogs? Diclofenac is an active substance included in the group of non-steroidal anti-inflammatories , that is, those commonly known as NSAIDs.They are products that are prescribed for pain relief, especially related to bone joint problems .Diclofenac can be used for dogs as long as it is prescribed by the veterinarian. Veterinary use of diclofenac Diclofenac for pain in dogs is used in veterinary me...

Dog breeds not recognized by the FCI

The FCI is the worldwide canine organization that approves pedigree dogs.There are several dog breeds not recognized by the FCI , even if they meet all the requirements to be considered "pure" breeds from the phylogenetic point of view. In this Animals and Pets Onlinet article We explain to you what these breeds are and why they are not recognized by the Federation Cynologique Internationale . Do not forget that the breed of the dog is not important unless you want to participate in morphology competitions canine.Read more: In many cases, breeds are not recognized by the FCI because they do not have a detailed written standard .In other cases because they do not meet the requirements established by the FCI.And in other cases, simply because no canine person or organization has bothered Evade the procedure so that these races are recognized by the FCI. It is also possible that political aspects outside the canine organizations have prevented the international diffu...

Animals and Pets Online

Search This Blog