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

Types of hummingbirds - Complete guide with pictures

The hummingbirds or hummingbirds are exotic birds of Small size, especially popular for its many characteristics and its beautiful shape.Although they stand out for having an extremely elongated peak, by which they extract the nectar from the flowers, they also captivate by their way of flying, which suspends them in the air while they emit a characteristic buzzing. Would you like to know what types of hummingbirds exist? What are they called or some of their particularities? In this article of ExpertAnimal we will show you a complete guide of types of hummingbirds with photographs , you can not miss it! Do not forget to leave us a comment explaining which is your favorite or share some curiosities! How many species of hummingbirds are there? The hummingbirds are very small birds that belong to the Trochilidae Family , whose members exceed 330 species that inhabit Alaska to Tierra del Fuego.However, of the more than 330 species of the Family Trochilidae only 4 are scienti...

10 reasons to walk your dog

The dog is an animal that needs to walk 2 to 3 times a day, But do you know why that is so? In this article of Animals and Pets Online we will explain why it is so important to walk with your dog, why the garden does not replace the walk and many other things that, perhaps you do not know. Do not forget This is a very important habit that you must carry out on a daily basis.Not doing so can be very harmful for your pet, do not forget it.Keep reading and discover 10 reasons to walk with your dog . 1.They must make their needs The first reason, and the most important , to take a dog for a walk, is to allow him to do his needs until he is satisfied. Apart from puppies that are not yet able to go outside or who are learning to urinate, it is very negative to allow our dog to urinate and defecate at home.In addition to causing a bad smell, we will be creating an unhealthy environment important that can lead to serious health problems in dogs and humans. 2.It allows them to ...

Why does my dog have 5 fingers on the hind legs?

Have you ever noticed how many fingers Do you have a dog in the front and back legs? You may have never noticed exactly, but dogs have 5 fingers on the front legs and 4 on the hind legs. However, sometimes we can see dogs that have 5 fingers on the hind legs , some even 6 and are called "ram".Do not be alarmed if this is your case, we will share with you all the necessary information so that you know why this characteristic is due and that you should (or don't). Keep reading this Animals and Pets Online article and discover why my dog has 5 fingers on the hind legs . Why do some dogs have spurs? The spur or "toe" on the hind legs of dogs is mainly due to genetics of a series of breeds concrete , although it can manifest itself in practically any dog.This characteristic does not represent any health problem and is not a disorder or malformation. It is believed that this claw that we can observe in the paws Rear could serve to give more support...

Types of wasps

The wasps are insects belonging to the family Vespidae and belonging to one of the largest orders of insects, where there are also ants, bumblebees and bees, among others.They are eusocial animals, although there are also some species that prefer solitude. One of the most distinctive characteristics of the wasps is the "waist", the area that divides the thorax of the abdomen.They can also be distinguished by having a stinger which they can use several times and not only once as in the case of bees. The wasps make their nest of mud or vegetable fibers; same that are in the ground, in trees, as well as in ceilings and walls of human rooms; All this depending on the type of wasp we are talking about.In this article of Animals and Pets Online you will know the different types of wasps , we invite you to continue reading. Subfamilies of Vespidos To better understand everything related to the types of wasps, we must detail that there are a total of 6 subfamilies of vespi...

Shih tzu hair care

The shih tzu bathroom Shih tzu hair care has a lot to do with the bathroom, which not only keeps the mantle clean but also free of knots.The frequency of the bath will depend on the type of Shih tzu activity, that is, if you leave home or not, if you play in the yard or in the park, among others.Before banning it, it is best to brush your hair to detect and undo possible knots . In general, it is best to bathe it once or twice a month , using warm water and a special shampoo and conditioner for dogs , never use products for humans in the dog's fur.While the dog is still a puppy, it uses hypoallergenic or tear-free products. The first bath of the shih tzu puppy Ideally, use it to the bathroom from an early age, in its socialization stage, and always using positive reinforcement, that is, try to associate this experience ns in a positive way .We can use toys, kind words, games in the water or infinite caresses. Just remember that you should not bathe a puppy 10 days b...

Tips to tame an arisco cat

Do you have an arisco cat and you don't know what to do? In this article of Animals and Pets Online we will show you what would be the necessary advice to tame and tame an arisco cat. Cats are generally very independent and solitary pets, although there is great individual variability.They also have a reputation."unfair", being considered as having unexpected reactions or directly as treacherous. Unfortunately, these reactions are common in cats, but more than being unexpected, most of the time they are misunderstood or even not understood, and can be provoked by the owners themselves.Discover some tips to tame an arisco cat and start enjoying feline life: What is a cat's behavior like? A cat is a lonely and territorial predator .Its territory is the house or place where it lives and shares it with some animal and some human (not all, so some human member can be considered as "non grato.") Tolerates relatively well the presence of other cats, alt...

Bach flowers for cats

In the last few years we hear frequent talk of Bach flowers, also applied to our Companion animals.There are more and more numerous cases treated with this therapy, as well as veterinary professionals who are trained in this discipline.In this article of Animals and Pets Online we will focus on cats to discover what Bach flowers are, which These are the benefits and uses they can have for our cats.If you've ever heard of these Bach flowers for cats , you're interested in reading! What are Bach flowers? The 38 extracts of flowers and plants discovered by the English doctor Edward Bach in the early twentieth century are called.This doctor chose plants that acted on different conditions that could experience the human beings, such as fear, sadness, anger or hyperactivity.Prepared these plants in the form of dilutions that conserved with alcohol in a dropper to facilitate their use.Various drops were administered directly several times a day or put in the water or even in t...

Andalusian Bodeguero dog or Andalusian mousetrap: features and photos

The Andalusian bulldog , originating from the province of Cadiz, formerly it was seen in the winery, hence its name, because it kept them free of rodent pests.Precisely for this same reason we know this dog breed as "Andalusian winemaker", "Andalusian mousetrapper" or "buzzard Andalusian winemaker ".Currently, he is a habitual companion of families, especially indicated for those with children, since he is very playful and sociable.If you want to know more about this wonderful and cheerful race, this article of Animals and Pets Online is made for you because you We explain everything about the Andalusian winemaker . Origin of the Andalusian winemaker dog Andalusian winemakers have strong roots throughout the southern part of the peninsula, but especially in the area of Jerez and the entire province of Cadiz in general.They used to work in the wineries., since they are expert rodent hunters , so they kept them free of these small animals that cou...

How do rabbits reproduce?

In this article of Animals and Pets Online we will talk about how they reproduce rabbits .We will see why they are popularly considered a very prolific species, although both freedom and captivity are many difficulties to overcome when it comes to getting and keeping their offspring.On the other hand, it is advised the sterilization of rabbits in captivity, whether male or female, to avoid health, behavior and overpopulation problems. Read on and discover all the curiosities about the reproduction of rabbits , how often they reproduce, such as mating and much more. The reproduction of rabbits The expression "reproduce like rabbits" is popularly used in reference to having a large number of children.This myth tells us about one of the curiosities of rabbits: their reproductive capacity.And it is that both males as the females begin their sexual maturity early, being able to copulate for days every few minutes.The rabbits have induced ovulation , that is, triggered by...

Differences between a Persian cat and an angora

Although both breeds are known and popular, for some lovers of cats the differences between a Persian cat and an angora are not entirely clear, perhaps because they both have a spectacular long coat, but the differences between both races are remarkable and, if we want to adopt any of these cats, it is important that we have them in order for our new cat to adapt as well as possible to our home. This is why in this article of Animals and Pets Online we will expose the differences between a Persian cat and an angora .If you intend to adopt any of these cats, this article of Persian cat vs Angora is essential! Physical differences between Persian and Angora cats We begin this review of the differences between a Persian cat and an angora for the most obvious, that is, those that refer to physical aspects.These are going to be the following: The nose: it is, perhaps, the most important and significant, in addition, at first glance it will allow us to differentiate a Persian cat a...

Animals and Pets Online

Search This Blog