oocytes (eggs) is usually embryonic form of an animal or the egg.The study deals with their oology - a special section of Zoology.
General
Their size may vary.For example, a mouse egg size about 0.06 millimeters, but the diameter of the embryonic form of the African ostrich can reach 15-18 centimeters.The shape may also be different.But usually the eggs are spherical or oval in shape.Some beings they may be elongated, lengthened, as for example mules fish myxines or insects.Depending on the extent and distribution of nutrients in the egg is determined by the size and other characteristics.Accumulation yolk (of the substance) is carried out or in the form of a solid mass, or in pellet form.Depending on the share of experts on different types of oocytes.The process of fertilization is carried out in the upper portion of the oviduct.In the course of the passage of the oocyte channel is crushed.This process takes place according to the type Banded incomplete.Due to the fact that the start of crushing occurs in the oviduct, delayed in birds egg can remain on one of the steps of crushing (such as a dove) go gastrulation (as a chicken).
Bird egg
females of all species of birds fauna lay oocytes.Different species lay eggs of different shapes.This is due to the place where it will be in masonry.For example, if the slot is arranged in the wells or pits, the eggs will be round.In birds, whose clutch is located on a rocky promontory, the oocytes are elongated.Generally, the larger the bird, the greater the size of the egg.But in this rule there are exceptions.For example, the types of brood, the offspring of which is adapted directly to independent feeding, lay eggs that are larger than (in comparison with the body of females) than those chicks that the light appears helpless.The ratio of the weight to the body weight of the oocyte at the smaller species are often larger than the larger species.It is believed that the greatest egg lays African ostrich.Regarding the body weight of the feathered representative, his oocyte is 1% of body weight.But the weight of a hummingbird eggs is 6% by weight of the birds.
Some structural features of bird eggs
have birds living in mountainous areas, the oocytes are "ribs" like stiffeners.They are necessary to maintain the integrity of eggs, so they are not broken when the birds land in the nest, having a small area.It should Mezhuyev other things, it noted that this edge is able to withstand a pressure of 40 kg / sq.cm, and the side, where it is not - no more than 2 kg / sq.cm. The surface of the egg is rough or smooth, shiny or matte.Color can be quite anything: from pure white to green and dark purple.The surface of the egg is covered with specks of some species, in some cases forming around blunt edge beater.The color will depend on the image and nesting sites.So, many secretly egg-laying birds and domestic birds shell is white.At the same ones who leaves laying on the ground, the color becomes identical environmental conditions: merges with stones or plant cloth that lines the nest.Its color egg gets another female in the birth canal.For example, biliverdin (pigment) in conjunction with zinc gives a blue or green color of the egg surface.Due protoporphyrin turns red or brown, or spots of colors.Next, we consider in more detail the internal structure of bird eggs.
device oocyte
structure of bird eggs corresponds to the destination.It contains everything necessary for the formation and development of the young organism.The embryo in the egg is powered by compounds found in the yolk.This mass is presented in two forms - in white and yellow.They are arranged in concentric layers alternating.The yolk is vitellinovoy membrane.It is surrounded by a protein.In the early stages of the shell egg poultry perform nutritional function.Protein, in addition, protects the new body from contact with the shell.The very content of the oocyte is surrounded by two layers podskorlupovymi: external and internal.Considering the structure of bird eggs, you need to say a few words about the very shell.It consists primarily of calcium carbonate.On the blunt edge of the oocyte after laying formed gradually airbag.
yolk
Considering the structure of bird eggs, the scheme of which is given below, it should be said that deytoplazma (yolk) is an integral component of the internal contents of the oocyte.The yolk mass collected all the necessary materials to ensure food and the normal development of the body.Deytoplazma detected in the egg not only birds and other animals (and humans), and is a collection of records or grains, in some cases, merging into a solid mass.The amount of the yolk, as well as its distribution can be varied.When a small amount of grain deytoplazmy or plates distributed uniformly in the cytoplasm.In this case we speak about "izoletsitalnyh" eggs.With a large number of yolk or components accumulate in the central region of the cytoplasm - or near the core of the vegetative part of the oocyte.In the first case we speak of tsentroletsitalnyh, while the second - telolecithal eggs.In accordance with the volume and the degree of distribution of the yolk weight is set and the type of crushing oocytes.The chemical structure of bird egg provides three types deytoplazmy.Yolk can be carbohydrate, fat or protein.But usually, the majority of individuals yolk components include, besides the above compounds, minerals, pigments, ribonucleic acid, having thus a complicated chemical structure.Thus, for example, ended growth in chicken oocyte yolk neutral fat contained 23% protein - 16%, 1.5% cholesterol, phospholipids - 11%, and 3% mineral compounds.The synthesis and accumulation of yolk component is the participation of different organelles: the mitochondria, endoplasmic reticulum, Golgi complex.The synthesis of the yolk protein component structure in many animals occurs outside the ovary.By pinocytosis protein component penetrates into the developing egg.
Other elements of the structure of the oocyte
All shell prevents spreading, drying and damage to the egg.But they do not provide the necessary moisture to the growing body.Its form extraembryonic organs.In particular, these include water (or amniotic) shell.Due to its limited amniotic cavity, which is filled with fluid, which, in fact, the body develops.Together with the water formed two layers: the vascular and serous (or allantois).In birds and reptiles, this layer is the organ allocation and breathing.From egg to blunt and sharp edges depart chalaza eggs - protein strands twisted tight.They provide a stable position in the nucleus, preventing displacement from the middle position.
Shell
studying the structure of the bird's eggs, should elaborate on the layers surrounding the nucleus.The most solid outer layer is a shell.It is quite thick and acts as a protection against mechanical damage and adverse environmental effects.Under the shell there podskorlupovye shell.On the blunt end they diverge and form an air chamber.It contains oxygen, which is necessary for the respiration of a new organism.
Trophic oocytes
There is a type of eggs that are in the masonry serve as food for the offspring.As a rule, they neoplodotvoreny, and their appearance does not differ from the ordinary.Their females lay some ants and termites uterus until such time as a colony begins to produce enough food.Unfertilized oocytes meat and egg and egg chicken breeds in some cases mistakenly referred to as trophic, because they are used in foods not by birds and humans and sometimes pets.
