Intersexuality

INTERSEXUALITY (from Latin inter- between and sexus-sex), a term introduced by Goldschmidt for the presence in the same individual of characteristics transitional in structure between male and female, or some characteristics male and others female. I., according to Goldschmidt, appears as a result of the organism's development first in the direction of one sex, then another, in contrast to gynandromorphism, in which the direction of development of certain body parts is predetermined from the very beginning and in the same individual certain parts are either purely male or purely female and may be located even on the same organ. I. occurs in both animals with non-centralized sex determination and with centralized sex determination, depending on hormones associated with the sex gland. Goldschmidt calls the first cases zygotic intersexuality, independent of certain irregularities in the sex cells from which intersexes develop, and the second cases hormonal intersexuality. There are two types of zygotic intersexuality. 1. The cause of intersexuality is the improper distribution of chromosomes; this includes so-called triploid intersexes. 2. I. depends on the combination of genes that determine development in the direction of a known sex, with a normal chromosomal apparatus - intersexes as a result of crossing different races. In triploid intersexes, instead of the usual diploid nucleus containing a pair of chromosomes of each type, a triploid nucleus is observed - with 3 chromosomes of each type, with only two X-chromosomes present. This phenomenon has been particularly thoroughly studied in the fruit fly (Drosophila) by Bridges. Bridges believes that the direction of development toward one sex or the other is determined by the ratio of the number of X-chromosomes to the number of sets of other chromosomes; in males there is 1 X-chromosome and 2 sets of autosomes, the ratio (sex index) = 1/2; in females - 2 X-chromosomes and 2 sets of autosomes, sex index = 1. Intersexes appear when the sex index is intermediate between male and female: 2 X-chromosomes and 3 sets of autosomes, sex index = 2/3. Thus, X-chromosomes mainly influence development in the female direction, while autosomes influence development in the male direction. Another case of zygotic I. was studied by Goldschmidt in crosses of different races of the gypsy moth (Lymantria dispar L.). If females of European races are crossed with males of Japanese races, various degrees (depending on which European and Japanese races are used for crossing) of transformation of females into males (female intersexes) are obtained. If a Japanese female is crossed with a European male and the females obtained in the offspring are again crossed with European males, various degrees of transformation of males into females - male intersexes - are obtained. Goldschmidt believes that the genes determining development in the male direction (M), in the gypsy moth in contrast to Drosophila, are localized in the X-chromosomes; the genes determining development in the female direction - in the X-chromosome, and in different races the 'strength' of action of these genes is different. Japanese races are strong, European races are weak, and among both European and Japanese races there are races of different strength. Within one race the action of F is stronger than the action of one M, but is suppressed by the action of 2M. In female butterflies there is one X-chromosome and one Y-chromosome (therefore M and F); in males there are 2 X-chromosomes (2M), there is no Y-chromosome, but according to Goldschmidt it influences further development before being separated into the directive body; thus in males there should also be one F. When a European female is crossed with a Japanese male, a combination of weak F from the mother and strong M from the father is obtained; the normal ratio is disrupted, and if M is sufficiently strong and F is weak, complete transformation of females into males can occur, in other cases various degrees of female I. appear depending on how weak F is and how strong M is. In the combination needed to obtain male intersexes, there is a strong F and 2 weak M's. If F is sufficiently strong and M is very weak, only females are obtained, in other combinations different degrees of male intersexuality are obtained. According to Goldschmidt, the more pronounced the I., the earlier the turn in development toward the other sex occurs. All organs whose direction of development was determined before this turning point develop in the direction of the original sex; those organs whose direction of development is determined after the turning point develop in the direction of the other sex; finally, those organs in which both moments coincide have an intermediate character. In some cases (wings in male intersexes) a mosaic alternation of male and female areas is observed. This mosaicism, according to Goldschmidt, is due to the fact that certain areas of the wing are somewhat delayed in the moment of determining the direction of development, therefore this moment for them falls after the turning point, and they become female, while in all other areas of the wing the direction of development was determined before the turning point, and they remain male. Zygotic I. of this type is sometimes also observed within one race in case of mutational change of F or M. Hormonal intersexuality arises because one hormone begins to act instead of another or the action of sex hormones ceases altogether. Goldschmidt considers it possible to assume that some cases of abnormal sex development in humans also belong to zygotic I. 'Undoubtedly, a whole series of abnormal sex conditions in humans can be associated with I. (retention of testis, hypospadias, underdevelopment of penis and testes, splitting of the scrotum, incomplete regression of ducts and uterus in males, and as the highest manifestation of intersexuality, pronounced hermaphroditism) assuming the same interpretation.'