Heterogamy is a type of sexual process in which cells differ from each other in form and structure
According to the Great Encyclopaedic Dictionary, heterogamy is a sexual process in which the female and male gametes that merge in the process of fertilization are different in size and shape.
The main types of sexual process
Isogamy, heterogamy, oogamy are all processessexual fusion of cells. Isogamy is the most primitive form of the sexual process, in which male and female cells have the same dimensions and are morphologically identical. Such a fusion is inherent in the simplest fungi and the equally-green algae.
Heterogamy is a sexual process, in which absolutely different in size and morphological structure merge sexual cells (gametes).
Oogamy - this is an order of magnitude different process of sexualthe fusion of cells, in which the sex cells are very different from each other. This type of sexual process is inherent in humans, as well as in some mammals. This type of fertilization occurs between a large female sex cell and a small male compared to it. Most often, the female cage is immobile, while the male is actively moving. This process can occur both within the female body and outside it.
The sex of organisms
It is generally accepted that there are two sexes: male and female. It should be noted, as we already know, that in nature there are three types of sexual reproduction: isogamy, heterogamy, oogamy. In all cases, complementary sex cells are formed, but only with oogamy an egg and a sperm are formed.
Types of sex determination
There are several types of sex determinationfuture offspring. The most commonly used three main methods: software, syllabic, metamogram. The most accurate of these is the software definition of the sex of the future offspring. These studies should be carried out until the very process of fertilization (ontogeny). So, for example, if we take a study of the sexual process of rotifers, then they have the ability to produce eggs of different sizes. Scientists have established that from eggs of large sizes, female individuals develop, and of small ones, only males.
Determination of sex directly duringthe sexual process of fertilization is syngamous. The analysis is carried out on the basis of the allocation of sex chromosomes. This type is the most common. Heterogamy is the main sexual process for the syngamous type of determining the future offspring.
Metamagic or epigamous type of sex determinationdoes not depend on the shape of the sex cells, nor on their size, nor even on the number of chromosomes. Determinative for this type of study are environmental factors, as well as the intensity of their impact. This type of definition of gender can be considered as modification variability.
Examples of the influence of external factors
The simplest and most common waymanagement of the sex of the future offspring can be considered on the example of crocodile eggs. Both in natural conditions and in the creation of artificial temperature conditions, at a certain temperature, either females or only males are born. It depends on the temperature.
There are also cases when on the floor of the futureoffspring are affected by the conditions in which they develop. Bonellia viridis is a species of annelid marine worm that has very specific abilities to change sex depending on the habitat.
The varying degree of influence of certain factors
The sex of the future organism is almost equaldegree affects both the genotype and a number of external factors. However, in different organisms the degree of influence on the gender of external factors and genotype is different. Determining the future sex of offspring in humans and most mammals is the genotype. To this kind of sexual process, like heterogamy, examples of which have been described previously, are primarily people. External factors do not influence this process in any way. While the same Bonellia viridis (a type of annelidant marine worm), described earlier, or the fish, are completely dependent on changes in the external environment.
The female of these worms greatly exceeds inthe size of his male, which has microscopic dimensions. He lives directly in the genital tract of the female. The larvae are bisexual, that is, they show signs of both sexes. That is why the sex of the future offspring is more influenced by environmental factors. So, the larva freely inhabiting the water column becomes a full-fledged female of large size. However, if she meets a female that is free from the male, she can fix herself on it and eventually become a male.
It happens that on the floor of the offspring of somemammals are influenced by external factors. In cattle, identical twins appear as a result of heterogamy. Even in the case when the cow develops at the same time heterozyte twins, the goby will be normally developed at the same time, and the male and female sex signs may appear in the female body. This feature is due to the fact that male sex hormones are released before the female and therefore can affect the sex of their twin. This example clearly shows the influence of external factors on the future sex of the offspring.
From the above, it follows that the base andthe biological basis of any change, including gender, is the original bisexuality of the body's genetic code. It is this feature that proves the fact that sex can change already as a result of the development of the body. And heterogamy is one of the main confirmations of this statement.