Gynandromorphism

GYNANDROMORPHISM (from Greek gyne - woman, aner - man and morphe - form), the combination in an individual of a normally sexually dimorphic species of male and female characteristics, where individual areas bear either purely male or purely female characteristics. In this case, the development of each such area proceeds from the very beginning in the direction of a particular sex, unlike with intersexuality, where development first proceeds in the direction of one sex and then the other, and where organs intermediate in structure are often encountered. With G., there can be a correct division into male and female halves, where the plane of division may pass through the plane of symmetry of the body, resulting in one side being of one sex and the other side of the other, or the anterior part bears characteristics of one sex and the posterior part of the other. A more irregular, mosaic distribution of areas of both sexes is often encountered, where areas of one sex may occupy significantly less space than areas of the other. In bilateral gynandromorphs, one gonad may be male and the other female. Such individuals are also often called hermaphrodites (previously this term included both true hermaphrodites and gynandromorphs and intersexes). G. has most often been observed in animals where the development of sexual characteristics depends exclusively on the chromosomal composition; the most gynandromorphs are known among insects. However, among vertebrates, where sexual characteristics are largely determined by the hormones of the gonads, gynandromorphs also occur. Bilateral gynandromorphs (division along the plane of symmetry) have been described in some birds. There are indications of finding gynandromorphs among mammals and even in humans (questionable cases, possibly intersexes). - The cause of G. is considered to be the early division of the embryo into male and female areas, for bilateral gynandromorphs - already at the stage of formation of the first two blastomeres. This can occur in various ways. In bees, where males develop from unfertilized eggs and females (queens and workers) from fertilized eggs, G. is the result of fertilization of one of the divided blastomeres; everything that develops from the fertilized blastomere will have female characteristics, everything that develops from the unfertilized one will have male characteristics. If gynandromorphs appear in a hybrid of two races, then the male parts should bear the characteristics of the mother (unfertilized part!), and the female parts should bear the characteristics of the hybrid, which was found when examining the coloration of gynandromorphic bees. In cases where sex is determined by the number of X-chromosomes in cells (2 X for one sex and 1 X for the other), several types of G. may occur. The most studied G. is in Drosophila, where it is caused by the loss of one of the X-chromosomes during division, resulting in one of the daughter cells having one X-chromosome and the other having two. If this happens at the first division of the egg, bilateral gynandromorphs are obtained; if at later stages, then mosaic ones. The later the loss occurs, the fewer cells with one X-chromosome there will be, and consequently the smaller the areas of male sex (in Drosophila the male has one X-chromosome). The correctness of this assumption has been proven by experiments crossing different races differing in traits whose genes are localized in the X-chromosome and in autosomes. Thus, the genes for gray coloration (dominant) and yellow (recessive) are localized in the X-chromosome. A gynandromorph (offspring of gray and yellow flies) turned out to be yellow on the male side and gray on the female side. It is clear that the X-chromosome carrying the gray color gene was lost. Other characteristics of the male part were typical of the hybrid, i.e., obviously it had autosomes from both father and mother.-Finally, a third type of gynandromorph formation is possible: the egg has two nuclei (due to the fusion of two eggs), and each of these nuclei is fertilized by a special sperm. In this case, if the male is heterozygous (i.e., has sperm of two types: with an X-chromosome and without it), fertilization of such an egg by two different types of sperm can occur, as a result of which one nucleus will be female and the other male. If the female is heterozygous, it may happen that one nucleus will extrude the X-chromosome into the polar body, while in the other nucleus it will remain. Two types of nuclei will be obtained: with an X-chromosome and without it. After fertilization, the first will be male, the second female. The two-nucleated condition of the egg can also result from the fusion of two polar bodies and the formation of a second nucleus from them. The latter phenomenon has been studied in butterflies (silkworm); it turned out that in them there is a tendency toward G., which is inherited by offspring according to Mendelian rules (see Mendelism) - the ability to form two-nucleated eggs (a recessive trait). Cases of G. in birds are explained by the fact that some cells become insensitive to one of the gonadal hormones. In females, both male and female hormones can develop, but male development is suppressed by the female hormone. If some cells are insensitive to the female hormone, they can give rise to male organs, p. kosshshkpj. Gynandria (see also the article Androgyny), a term proposed by Krafft-Ebing for the presence in women of male secondary sexual characteristics. Gynandrias are women who differ in coarse bone structure, with a male torso and pelvis, flat mammary glands, a low, rough voice and a tendency to grow facial hair. Male traits - aggressiveness, dominance, decisiveness, a desire for activities requiring physical strength - are usually noted in their character as well. Sexual desire is often perverted in the sense of homosexual inclinations, but can be completely normal (however, gynandrias choose male partners who are predominantly weaker and milder than themselves themselves). Apparently, the basis of the phenomenon described is insufficient sexual differentiation (intersexuality, see). It hardly has anything in common with true gynandromorphism.