Reptiles

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After ovulation occurs, the egg leaves the ovary and enters the oviduct, where fertilization takes place. Along the path of the egg to the oviduct is made the initial phases of gastrulation and segmentation during this process the glands found on the walls secrete albuminous substances that adhere to and form the clear egg or albumin. As the oviduct has a twisted configuration presents inside walls with spiral folds, where the egg turns, the twists and albumin are the germ cell.
During this trip, other layers are formed of organic substances which are called the shell membranes and eventually form the shell or calcareous layer surrounding the egg.
A)
Segmentation
The segmentation of the egg is meroblástica, because the mass of yolk prevents deepening levels of segmentation in the egg, the segmentation begins in the oviduct after fertilization occurs and is confined in the center of a tiny portion that is in the animal pole, called the blastodisc.
Segmentation begins with the formation of a vertical groove in the blastodisc, the second groove, crosses perpendicular to the first, then you have new drills segmentation occurring in the area of the blastodisc, the yolk remains indivisible and when finished segmentation many cells are formed, there begins to form the blastula and blastocoel is formed.
B) The Blastula
During the early stages of cleavage, the blastomeres remain attached giving the egg looks like a blackberry, is the morula stage. But soon, the blastomeres tend to lie around a central cavity or blastocoel, leaving the blastula stage, until now there has been an increase in size, but there is simply more cells are smaller, which does increase in number is genetic material.
PRIMARY-Blastula
Around 32-64 blastomeres stage a new type of division. It is cytoplasmic in deep divisions that determine a lower limit
for certain blastomeres, separated from the yolk through a virtual even split. During subsequent cleavages, the mass of central blastomeres located above the crack grows and células.Divisiones are horizontal layers of separating the upper marginal cells and in cells without boundaries with the underlying yolk Cleft grows and forms the central primary blastocoel. From the moment the segmentation cavity appears, the blastoderm has outwardly two regions: the area pellucida and area opaca. The area pellucida is for the central part of the blastoderm, and the rest on the blastocoel appears lighter.
The opaque area corresponding to the peripheral blastoderm layers, and includes:
* Peripheral blastomeres form the coating zone and whose cells actively divide the yolk, without joining it.
* An area that is united blastomeres without definite limits to the yolk. * An inner zone of transition between the opaque area and the area pellucida
-Blastula SECONDARY:
Blastoderm, at the area pellucida, is transformed into a germ Diploblasty. The superficial cell layer represents the ectófilo, while the deepest layer is called entófilo. The blade could come from entófilo delamination area pellucida.
The blade entófilo primary blastocoel separates into two chambers:
* the Archenteron directly above the yolk (yolk). * The secondary blastocoel between ectófilo and entófilo.
. Blastula AN AVE
B) Gastrulation
This process began in the early hours of incubation, the segmentation by constant divisions that causes the blastoderm consists of several layers of cells, the part that emerges from the yolk has a clear appearance is called the zona pellucida, there is some darker cell layer that is called a gray area.
In the back of the zona pellucida is a thickening that is stretched to the middle of this area. When it lengthens the line starts early process that takes place between 10 and 12 hours.
The blastodisc is stretched and differentiate three layers are: the ectoderm, mesoderm and endoderm, between 18 and 20 hours of incubation of the egg, gastrulation is completed and begins the Neurula, which begins with a thickening the knot in front Hensen, called extension cephalic neural folds are formed, the plate and the neural cord, somites are differentiating and leave the body organs
.-.- BIRTH OF BIRDS
Many birds start to incubate after laying the last egg, others do after laying the first egg, the chicks born on.
In many families, it is only the female that incubates, but rarely this task is shared by both partners. And something very strange is that the task of incubation is assumed by the male. Also, several birds do not incubate their own eggs, either because they have in other nests or because they are buried in hot sand.
At birth, the chicks are very different from species to species. Some have feathers and are able to walk or even swim the fly-talégalos; only need the protection of their parents, who feed them. This applies to the nidífugas, such as ducks, chickens, turkeys, partridges, etc..
The duration of the incubation period varies mainly depending on the size of birds. The chick breaks through egg out through a body called "peak tooth, which protrudes from the upper jaw. He uses it to tear a small corner of the shell. This "tooth" disappears soon after birth





After ovulation occurs, the egg leaves the ovary and enters the oviduct, where fertilization takes place. Along the path of the egg to the oviduct is made the initial phases of gastrulation and segmentation during this process the glands found on the walls secrete albuminous substances that adhere to and form the clear egg or albumin. As the oviduct has a twisted configuration presents inside walls with spiral folds, where the egg turns, the twists and albumin are the germ cell.
During this trip, other layers are formed of organic substances which are called the shell membranes and eventually form the shell or calcareous layer surrounding the egg.
After the egg ends up touring the oviduct falls in the gutter, only to be expelled outside. The time it takes the egg to form from the time of ovulation until the end of the oviduct is about 16 to 20 hours.
A) Segmentation
The segmentation of the egg is meroblástica, because the mass of yolk prevents deepening levels of segmentation in the egg, the segmentation begins in the oviduct after fertilization occurs and is confined in the center of a tiny portion that is in the animal pole, called the blastodisc.
Segmentation begins with the formation of a vertical groove in the blastodisc, the second groove, crosses perpendicular to the first, then new rows appear segmentation occurring in the area of the blastodisc, the yolk remains indivisible and when finished segmentation many cells are formed, there begins to form the blastula and blastocoel is formed.
B) The Blastula
During the early stages of cleavage, the blastomeres remain attached giving the egg looks like a blackberry, is the morula stage. But soon, the blastomeres tend to lie around a central cavity or blastocoel, leaving the blastula stage, until now there has been an increase in size, but there is simply more cells are smaller, which does increase in number is genetic material.
PRIMARY-Blastula
Around 32-64 blastomeres stage a new type of division. It is cytoplasmic in deep divisions that determine a lower limit
for certain blastomeres, separated from the yolk through a virtual even split. During subsequent cleavages, the mass of central blastomeres located above the crack grows and células.Divisiones are horizontal layers of separating the upper marginal cells and in cells without boundaries with the underlying yolk Cleft grows and forms the central primary blastocoel. From the moment the segmentation cavity appears, the blastoderm has outwardly two regions: the area pellucida and area opaca. The area pellucida is for the central part of the blastoderm, and the rest on the blastocoel appears lighter.
The opaque area corresponding to the peripheral blastoderm layers, and includes:
* Peripheral blastomeres form the coating zone and whose cells actively divide the yolk, without joining it.
* An area that is united blastomeres without definite limits to the yolk. * An inner zone of transition between the opaque area and the area pellucida
-Blastula SECONDARY:
Blastoderm, at the area pellucida, is transformed into a germ Diploblasty. The superficial cell layer represents the ectófilo, while the deepest layer is called entófilo. The blade could come from entófilo delamination area pellucida.
The blade entófilo primary blastocoel separates into two chambers:
* the Archenteron directly above the yolk (yolk). * The secondary blastocoel between ectófilo and entófilo.
. Blastula AN AVE
B) Gastrulation
This process began in the early hours of incubation, the segmentation by constant divisions that causes the blastoderm consists of several layers of cells, the part that emerges from the yolk has a clear appearance is called the zona pellucida, there is some darker cell layer that is called a gray area.
In the back of the zona pellucida is a thickening that is stretched to the middle of this area. When it lengthens the line starts early process that takes place between 10 and 12 hours.
The blastodisc is stretched and differentiate three layers are: the ectoderm, mesoderm and endoderm, between 18 and 20 hours of incubation of the egg, gastrulation is completed and begins the Neurula, which begins with a thickening the knot in front Hensen, called extension cephalic neural folds are formed, the plate and the neural cord, somites are differentiating and leave the body organs .-.- BIRTH OF BIRDS
Many birds start to incubate after laying the last egg, others do after laying the first egg, the chicks born on.
In many families, it is only the female that incubates, but rarely this task is shared by both partners. And something very strange is that the task of incubation is assumed by the male. Also, several birds do not incubate their own eggs, either because they have in other nests or because they are buried in hot sand.
At birth, the chicks are very different from species to species. Some have feathers and are able to walk or even swim the fly-talégalos; only need the protection of their parents, who feed them. This applies to the nidífugas, such as ducks, chickens, turkeys, partridges, etc..
The duration of the incubation period varies mainly depending on the size of birds. The chick breaks through egg out through a body called "peak tooth, which protrudes from the upper jaw. He uses it to tear a small corner of the shell. This "tooth" disappears soon after birth

1 - Preparation for Birth: The prelude to the birth, they are invisible. The chick inside the shell turns up positioned so that its beak points to the rounded side of the egg and then a sharp header, drill the air bag.
2 - Rupture of the shell: The birth begins when the chick gets, after several attempts to break the shell. They help of two basic elements: "the tooth of the peak, a small organ that protrudes from the upper jaw and falling soon after birth, and a powerful muscle located behind the head, which reinforces the thrust of the tooth
3 - The crack takes shape: After breaking the shell by a point, the chick begins to extend the crack. After each peck, stops and turns slowly pushing with their feet to enlarge the crack. This process of turning and biting produces a crack around the base of the egg.
4 - The fissure becomes cracking around the egg
5 - The position ensures chick: The chick finger grabs the shell rim, and as has secured its position, pushing with the legs and shoulders.
6 - The birth itself: The chick pushes once more with the feet and the rounded side is left on his head, like a Shade
7 - Life in the outside world.

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