Egg cell

Eggs (eggs and eggs) is a female creature germ cell . Animal and plant seeds can produce eggs.
Egg cell

Egg cell The egg.

 The egg cell structure The egg cell structure
stay Higher organisms On the egg cell is made ovary The. All Mammals At the time of birth, have immature egg cells in the ovaries, and increase the number of eggs not after birth. The egg and sperm Combined fertilization will form a fertilized egg, which is the beginning of a new life. Some animal (such as birds) is In vivo fertilization The other animal (such as most of the fish) was carried out in vitro fertilization. In human reproduction, essential to the number of eggs. Egg Is the largest cell in the human body, but also the unique female cells, is the creation of new life mother cells .

Egg cell Structural components

The egg cell is spherical, with a nucleus, by Vitelline membrane Surrounded by a .
 Vitelline membrane Vitelline membrane
The egg outside with outside (coat), the main component is glycoprotein That is an egg cell or other cells. In mammals this was called Transparent tape (Zonapellucida), its role is to protect the eggs, prevent heterologous sperm into the. With many eggs (transparent below the cortex, cortex) and a layer of secretory Vesicle Called. cortex The particles (corticalgranules), can cause changes in the structure of the zona pellucida fertilization except when the row release mode of cortical granule formation. Fertilization membrane Stop, other sperm Get into。 The egg cell has more cytoplasm than sperm

Egg cell Production process

The egg cell is by what we say normally -- female gonad ovary produces, a diameter of about 0.1mm. In addition to the main function of ovarian secretion of female sex hormone is required, produce eggs. The girl in the The embryonic period The prototype is about 3 ~ 6 weeks has already formed the ovary. Before birth, the ovary has millions of Oocyte After the formation of childhood, Puberty Also, to adult only more than 100 thousand oocytes. Oocytes wrapped in Primordial follicles In the influence of sex hormones, only one month of primordial follicles mature, mature eggs from the ovary is discharged into the abdominal cavity. Generally speaking, the eggs mature female life is about 300 ~ 400, the rest of the oocyte will emerge of itself and perish of itself.
In general, each menstrual cycle only one oocyte maturation. In so doing, the woman from the beginning of menarche, menopause around the age of 45 to date, there are more than and 500 of the oogonia to mature. In the process of follicular growth, their volume will slowly become larger, bubble liquid will gradually increase, and will gradually shift from the ovary to the ovarian surface, finally protruding from the ovarian capsule. After the egg cell fully developed in sex hormones and enzymes in the body under the action of will make the dissolution and rupture of theca and fibrothecomas, follicular fluid discharge, the release of the oocyte, which is ovulation. Women of childbearing age, every month in a row of eggs.
 Produce egg cells Produce egg cells
An egg cell after discharge can survive for 48 hours, during the 48 hours waiting for the meeting, combined with the sperm. If the egg and sperm can not meet due to various reasons the formation of fertilized eggs, in 48 ~ 72 hours after natural death. Lose the chance of fertilization, we will have to wait for another 1 months after the mature eggs and is expelled, repeat the same process. About two of the ovarian ovulation is usually in a few cases, can also emit two or more than two eggs. If were combined with sperm, appeared dizygotic twins and multiple egg twins.
In cause Female infertility The reason, ovarian factors causing infertility infertility accounted for 15% ~ 25%, ovarian anovulation is one of the important reasons.

Egg cell The migration process

The main part of the egg is running Fallopian tube The role of umbrella end. According to the direct observation of some animal, the egg in the abdominal cavity after ovulation does not walk a long distance. The contraction of muscles, fallopian tube and ovary mesangial ligaments with each other, the fallopian tube and ovary were very close to. In humans, the operation is often seen around the fallopian tube to uterus The rear estimate may be similar features with the mammalian eggs they capture fallopian tube.
The egg into the fallopian tube is mainly due to the effect of picking up fallopian tube. In 2013, people observed under direct vision and found the ovulatory follicle rupture is not violence to put the egg into the abdominal cavity, but with follicular fluid Cumulus Cell The secondary oocyte After ovulation points flowing slowly. After ovulation due Progesterone The role of fallopian tube is widely dispersed, hyperemia, oviduct contraction strength increases, and the umbrella side away from the close and umbrella end point ovulation number cilia The swing, a few minutes of eggs was quickly sent to the ampulla. Oviductal fluid in the fallopian tube narrow part flow faster, while in the ampulla of flow rate is very slow, so the egg in the ampulla and stay here fertilization. The egg is released from the ovary after 15 to 18 hours, the best fertilization effect, if not fertilized within 24 hours of starting degeneration.

Egg cell Different classification

Egg cell Human eggs

Male and female since adolescence, sexual organs, testis or ovary There were mature sperm or Egg Discharge. The women's normal ovarian monthly discharge a most mature eggs, sperm about 3 days can be a number of mature, every time can have millions of sperm output. Period of ovulation In the next 14 days before menstruation, when an egg from the ovary after discharge, fallopian tube pick up eggs, with cilia function, only a few minutes into the distal and central 1/3 tubal junction (i.e. Fallopian tube Pot belly), and stay in the 2~3 days waiting for fertilization. So during the period of sexual life, sperm into the Vagina After 2~3 hours by vaginal transcervical uterine tube, quickly walks into the fallopian tube and the egg. A large number of competing sperm into the egg, but as long as there is a broken egg sperm first peripheral tissues, into the egg, the other sperm would not be in the same egg. The cell membrane rupture into the sperm and egg cells after contact with the head, the periphery of the nuclear fusion. Transparent tape Then harden, sperm and oocytes of prokaryotic fusion became pregnant eggs, at each into 23 Chromosome fusion As of 23. The egg cell can affect children born.

Egg cell Egg plant

 The female egg electron microscope The female egg electron microscope
The formation process of egg cells of higher plants occurred in the ovary. ovule In. The ovule inside a megaspore mother cell, megaspore mother cell meiosis, into four cells, one of the larger cell development Embryo sac cells Three, the small cells did not develop future disintegration. The embryo sac cell nuclei after three times continuous mitosis, the formation of the "seven eight cell nuclear" embryo sac This, eight nuclei. Chromosome With the same number of embryo sac cells is The embryo sac mother cell Half. and germ cell Is directly related to an egg cell located near the micropyle and embryo sac, located at the center of the two Polar nuclei . Fertilized zygote formation, two polar nuclei formed after fertilization Polar nucleus fertilization This is called, fertilization Double fertilization That is only found in angiosperms. Sperm come from? In the anther in stamen Pollen mother cell That number, each must go through meiosis to produce four pollen cells, referred to as pollen, their chromosomes only half of the original. When the pollen germination on the stigma, they also make a nuclear Mitosis The formation of a. Generative nucleus A Vegetative nucleus Again, the generative nucleus mitosis to form two sperm.