When two cages merge together to give rise to a new life, there is a conception. At the person, as well as at all mammals, one of two these cages occurs from adult man's, and another - from the adult female individual. A man's cage n azyvaetsja spermatozoidom, female - jajtsekletkoj or jajtsom.
The New life arises at the moment of conception, i.e. When spermatozoid and jajtsekletka merge in a single whole. Their merge occurs in an organism of the woman owing to sexual intercourse between the future parents. After conception the fruit continues to develop in a body of mother while to it does not come it is time to be born.
Spermatozoidy are formed of sexual cages, or spermatogony which as all other cages of an organism, have 23 steams of chromosomes and are capable to grow and share. Ripening and ready to fertilisation spermatozoidy are stored in man's gonadah (reproductive bodies) - two jaichkah, hidden in order to avoid an overheat in a special external sack, or moshonku. The matter is that for development spermatozoidov lower temperature, than for all other functions of an organism is required.
Female jajtsekletki are formed from oogony, also by allocated 23 steams of chromosomes, but ripen in an organism in two tanks named jaichnikami.
Before there will be a meeting spermatozoida and jajtsekletki, pair chromosomes should be divided on unary to merge with 23 unary chromosomes of other cage and to form 23 new steams. Thanks to this division the germ inherits half of characteristics of the father and half - mothers. Process of division of pair chromosomes is called mejozom.
Ripened and ready to division process spermatogonija is called spermatotsitom I order. At this stage there is a division of pair chromosomes at which in each of two new cages there is a half of each pair. Now new cages (spermatotsity II order) contain 23 unary chromosomes.
The Same division of pair chromosomes occurs and in developing jajtsekletke. Ripened oogonija it will be transformed in surrounded with a follicle ootsit I order, and in process mejoza its pair chromosomes too are divided into the unary.
From this point on cell fission occurs under other scenario. At the second stage mejoza together with everyone spermatotsitom II order share in two and unary chromosomes. Their halves get into again formed cages and as a result two mutually combined cages are formed, each of which is supplied by a totality from 23 halves of unary chromosomes.
These new cages are called sperm tidami. The roundish form they on remember spermatotsity I and II order, but should pass still a number of transformations to become high-grade spermatozoidami with an oval little body, zhgutikom and a set from 23 unary chromosomes. All these changes occur in cages of Sertoli, or sustenotsitah, and their end result becomes extended at length spermatozoid with a head filled with a genetic material from 23 unary chromosomes and apikalnym by a little body, or akrosomoj.
Progress spermatozoida is provided with palpation zhgutika, with standing of cylindrical fibres.
In a head contain enzimy (sperm tidnyj mitohondry), capable to split nutrients and to supply with energy mature spermatozoidy.
Ready to fertilisation spermatozoidy separate from sustenotsitov and arrive in a long twisting tube - an appendage jaichka, located in its back part where they definitively ripen and become covered by a cellular cover. There they wait three-four weeks the hour together with millions others spermatozoidov, and in a case not needs are soaked up back in an organism. All development spermatozoida from origin to destruction lasts about two months.
Female gonady, or jaichniki in which maturing jajtsekletki begins, are located in the field of a small basin and are connected to a uterus in pair fallopievyh pipes.
Jajtsekletka ready to transformation from ootsita of I order in ootsit of II order, still is in a follicle jaichnika. On dobno spermatotsitu I order, it too passes the next stage mejoza with that only a difference that two mutually combined cages as a result are not formed.
As a result of division ootsita I order two unary chromosomes, however one of two new cages are formed of each pair of chromosomes (ootsitov II order) another turns out more. It also develops in mature jajtsekletku. The smaller cage (or a polar little body with the same set of 23 unary chromosomes) moves to a transparent zone round initial ootsita I order and there perishes. Remained ootsit II order with its transparent zone it is similar the form on spermatidu though and is much larger than last. After day-two it on fallopievoj to a pipe falls from jaichnika to a uterus cavity where undergoes secondary division. JAjtsekletka cannot move independently, and on fallopievoj to a pipe it is pushed tiny, similar on resnichki vyrosty, and also by reductions of the pipe. This process named ovuljatsiej, monthly occurs at all women of genital age.
Now ripened jajtsekletka it is ready to conception of a new life which will occur at a meeting with spermatozoidom. This meeting also is called as fertilisation. Only after that jajtsekletka undergoes one more change.
Mature jajtsekletka waits fertilisations in a uterus cavity about one day and if it does not occur, perishes. Spermatozoidy can wait the hour about one month, but after sperm emission too live not longer one day. The appendage jaichka in which are stored mature spermatozoidy, is connected with semjavynosjashchim a channel, and through it - to an urethra, or mochevyvodjashchim the channel, in a sexual member of the man. JAjtsekletka all time is in a uterus cavity.
Spermatozoidy get to a vagina with emission of a seed liquid. At one portion of a liquid can be present about 250 million spermatozoidov which immediately start to move to a uterus though not all reach the purpose. If at the moment of sexual intercourse is available ready to fertilisation jajtsekletka, the probability of conception is high enough.
Before there will be a fertilisation, spermatozoidy should spend some time in an organism of the woman. For this period (at the person approximately 7 hours) occur preparatory changes. Containing in a head spermatozoida enzim will neutralise the acid environment round a transparent zone, opening a way to jajtsekletke. For destruction of this external barrier are required enzimy sets spermatozoidov, but in jajtsekletku one of them gets only.
Hardly one spermatozoidu will manage to get in jajtsekletku, it immediately becomes impenetrable for the others. External covers spermatozoida and jajtsekletki are dissolved, and two cages merge in one, giving rise to the second stage mejoza. Threads of 23 chromosomes, waiting the pair in jajtsekletke, incorporate to unary chromosomes spermatozoida. At this stage man's and female chromosomes have received the name man's and female pronukleusa. They increase in time to a measure and approach to meet in the center jajtsekletki. Their covers merge, and two groups of chromosomes incorporate in pairs. The high-grade uniform cage is as a result formed. This cage is called as a zygote and represents the beginning of a new life. It contains the genetic information necessary for the further development of the human being. After fertilisation the follicle in which has developed jajtsekletka, continues to grow, turning to gland named a yellow body. Its problem - to carry out transformations to the transparent zone, not supposing penetrations in jajtsekletku others spermatozoidov, and to provide normal growth and development impregnated jajtsekletki.
Each individual receives exactly half of chromosomes from mother, and other half - from the father. In each chromosome numerous genes contain; each gene supervises inheritance of one or several signs. In each pair homologous (similar, in pairs incorporating at mejoze) chromosomes genes are located in an identical order. As chromosomes disperse in mejoze and perekombinirujutsja at fertilisation, the same occurs and to genes. Depending on character of interaction of genes the descendant can resemble one parent more than on another, but both parents bring the identical contribution to its heredity.