XY follicle cells in the ovaries of XO/XY and XO/XY/XYY mosaic mice

XO/XY and XO/XY/XYY mosaic hermaphrodites were generated from crosses involving BALB/cWt males. The distribution of Y-bearing cells in the gonads of these mice was studied by in situ hybridisation using the Y-specific probe pY353B. XY cells were found to contribute to all cell lineages of the ovary including follicle cells. The proportion of XY follicle cells was not significantly different from the XY contribution to other gonadal or non-gonadal cell lineages. However, this proportion was consistently low, all the hermaphrodites having a low XY contribution to the animal as a whole. Because the XO- and Y-bearing cell lineages are developmentally balanced, the XY follicle cells cannot have formed as a result of a 'mismatch' in which the Y-directed testis determination process is pre-empted by an early acting programme of ovarian development. These results are discussed with respect to the hypothesis that Tdy acts in the supporting cell lineage, the lineage from which Sertoli cells and follicle cells are believed to be derived.     

Assays of testis development in the mouse distinguish three classes of domesticus-type Y chromosome

The Y chromosome of Mus musculus poschiavinus interacts with the autosomal recessive gene tda-1b of the C57BL/6J laboratory strain of the house mouse to cause complete or partial sex reversal. Ovaries or ovotestes develop in a substantial proportion of the XY fetuses. Several different Y-specific DNA probes distinguish two major types of Y chromosome in the house mouse and they are represented by M. m. domesticus and M. m. musculus. The poschiavinus Y chromosome appears identical to the domesticus Y. The developmental distribution of the gonad types was examined in the first backcross or N2 generation of fetuses in C57BL/6J with six different domesticus-type Y chromosomes and, as controls, three different musculus-type Y chromosomes. Gonadal hermaphrodites were found with three of the six domesticus-type Y chromosomes. Both overall frequency and phenotypic distribution of types of gonadal hermaphrodites identify three classes of domesticus-type Y chromosome by their differential interaction with the C57BL/6J genetic background.     

Studies on the genetics of tda-1 XY sex reversal in the mouse

When the Y chromosome of at least some populations of the house mouse of Western Europe and the Mediterranean, Mus musculus domesticus, is placed into the C57BL/6J (B6) inbred mouse genome, XY fetuses develop into hermaphrodites or females. It has been hypothesized that the testis-determining gene on the Y chromosome of M. m. domesticus (TdyDOM) interacts improperly with a putative B6/J recessive, testis-determining, autosomal gene (tda-1). The present study extended these earlier findings. The mating of B6 mice possessing the Y chromosome of M. m. domesticus (B6.YDom/Na; N6-N9) to females of the AKR, BALB/c, C3H/An, and C3H/He, but not SJL, strains resulted in aberrant testicular differentiation in day-14/15 F1 fetuses. The aberrant testes were characterized by a delay in testicular differentiation at the cranial and caudal poles of the gonad, i.e., the presence of a thin (or no) tunica albuginea and the presence of disorganized (or no) seminiferous tubules. Crossing B6.YDom male phenotypes with SJL females did not result in aberrant testicular differentiation, suggesting that the SJL strain possesses the dominant testis-determining, autosomal-1 allele, Tda-1. Studies using recombinant DNA probes specific for the murine Y chromosome have suggested that the SJL and AKR strains possess the M. m. domesticus Y chromosome. When Y chromosomes of the SJL and AKR strains were placed on the B6 background, aberrant testicular differentiation similar to tda-1 XY sex reversal occurred in only 1 out of 87 (1%) N4 day-14/15 fetuses possessing YSJL, but in 25 out of 45 (56%) N4 day-14/15 fetuses possessing YAKR.(ABSTRACT TRUNCATED AT 250 WORDS)     

Inheritance of T-associated sex reversal in mice

We previously identified a primary sex-determining locus, Tas, on mouse Chr 17 that causes ovarian tissue development in C57BL/6J Thp/+ and TOrl/+ individuals if the AKR/JY chromosome is present. We hypothesized that Tas is located within the region of Chr 17 deleted by Thp and TOrl and that C57BL/6J carries a diagnostic Tas allele, based on the observation that ovarian tissue develops in XY mice when Thp is on a C57BL/6J inbred strain background, whereas normal testicular development occurs when Thp is on a C3H/HeSnJ inbred strain background. To test this hypothesis, we mated (C57BL/6J x C3H/HeSnJ)F1 females to C57BL/6J Thp/+ hermaphrodites. As expected, half of the XY Thp/+ offspring developed ovarian and testicular tissue while half developed exclusively testicular tissue. Unexpectedly, the inheritance of selected Chr 17 molecular loci was independent of gonadal development, as half of the male and hermaphroditic offspring inherited C3H/HeSnJ-derived Chr 17 loci and half inherited C57BL/6J-derived Chr 17 loci. We conclude that for ovarian tissue to develop in an XY Thp/+ or XY TOrl/+ individual (1) Tas must be present in a hemizygous state, which is accomplished by heterozygosity for the Thp or TOrl deletions; (2) the AKR/J-derived Y chromosome must be present; and (3) an additional locus involved in primary sex determination must be present in a homozygous C57BL/6J state. This newly identified gene may be one of the previously defined loci, tda-1 or tda-2.     

Does one gene determine whether a C57BL/6J-Y(POS) mouse will develop as a female or as an hermaphrodite?

Two studies were conducted to further our understanding of the inherited condition in mice known as C57BL/6J-Y(POS) (B6-Y(POS)) sex reversal. One study determined what proportion of B6 XY(POS) mice develop as females or hermaphrodites. We found that 75% develop as females and the remainder develop as hermaphrodites regardless of whether the analysis is conducted at 14.5-16 days of embryonic development (based on gonad phenotype) or at weaning (based on the appearance of external genitalia and presence of mammary-associated yellow pigmented hair). We also found that 75 % of the gonads in B6 XY(POS) mice develop as ovaries and the remainder develop as ovotestes; none develop as a testis. We conclude that if any testicular tissue develops, sufficient testosterone is produced to cause at least some masculinization of the external genitalia. The second study tested the hypothesis that development of testicular tissue in B6 XY(POS) mice is due to the presence of a POS-derived gene, whereas B6 homozygosity of this gene guarantees ovarian development. The results did not support the POS gene theory. Therefore, we conclude it is a matter of chance that 75 % of B6 XY(POS) mice develop as females and 25 % develop as hermaphrodites.     

Müllerian inhibiting substance in sex-reversed dogs

In normal males, Müllerian Inhibiting Substance (MIS), produced by testes during an embryonic critical period, is thought to induce regression of the Müllerian duct system, including the oviducts and uterus. In XX sex-reversed dogs, an apparent contradiction has been reported: The uterus persists in the presence of testes or ovotestes. The objective of this study is to determine whether testes of XX male and ovotestes of true hermaphrodite dogs produce MIS, and to examine the anatomy of Müllerian duct derivatives of affected dogs for evidence of regression. Gonadal samples were tested for MIS activity in a bioassay. The mean MIS activity score of XX males was similar to that of normal XY males and significantly greater than that of normal XX females. The mean MIS activity score of XX true hermaphrodites was intermediate between normal XX females and XY males. Within the true hermaphrodite group, ovotestes in which the proportion of testicular tissue was greater than or equal to 1/2 had higher MIS scores than those in which the proportion of testicular tissue was less than 1/2. XX males had a well-developed epididymis adjacent to each testis, but no oviducts. In true hermaphrodites, the oviduct regressed and an epididymis was present when greater than or equal to 1/2 of the adjacent ovotestis was testicular, and MIS activity in that gonad was high. A few ovotestes with intermediate levels of MIS activity had both an oviduct and an epididymis. Regression of the oviductal portion of the Müllerian duct system was positively correlated to the amount of testicular tissue and the MIS activity of the gonad, as would be predicted by Jost's original hypothesis.(ABSTRACT TRUNCATED AT 250 WORDS)     

XX sex reversal in the American cocker spaniel dog: phenotypic expression and inheritance

Summary This study was conducted to define the range of phenotypic expression and mode of inheritance of XX sex reversal in the cocker spaniel dog. Breeding experiments produced F1, F1BC, and F2 generations in which 29 XX true hermaphrodites and 3 XX males were defined by chromosome constitution, serial histologic sections of the gonads, and examination of the internal and external genitalia. In XX true hermaphrodites, the most common combination of gonads was bilateral ovotestes, followed by ovotestis and ovary, then ovotestis and testis. The amount of testicular tissue in the two gonads was closely correlated within each true hermaphrodite. The distribution of testicular tissue within ovotestes of true hermaphrodites was consistent with the hypothesis that testicular differentiation is initiated in the center of the gonad and spreads outward. XX males had bilateral aspermatogenic testes and the internal ducts and external genitalia were more masculinized than in true hermaphrodites. Results of breeding experiments are consistent with autosomal recessive inheritance, the affected phenotype being expressed only in dogs with an XX chromosome constitution. The phenotypic expression and mode of inheritance of this disorder is compared to XX sex reversal in humans and other animals.     

Inherited XX sex reversal in the cocker spaniel dog

Summary Nine XX true hermaphrodites and two XX males were discovered in a family of American cocker spaniels. The true hermaphrodites were partially-masculinized females with ovotestes; the XX males had malformed male external genitalia and cryptorchid aspermatogenic testes. Wolffian and Mullerian duct derivatives were present in both true hermaphrodites and XX males. All four sires of sex-reversed dogs were normal XY males; five of the dams were anatomically normal females and one was an XX true hermaphrodite. A second true hermaphrodite reproduced as a female, producing anatomically normal offspring.All matings that produced sex-reversed offspring were consanguineous. Matings of the parents of sex-reversed cocker spaniels to normal beagles with no family history of intersexuality produced only normal offspring. Examination of G-banded karyotypes of the affected animals, their parents, and siblings, revealed no structural anomalies of the chromosomes that were consistently associated with sex-reversal.In assays for serologically-detectable H-Y antigen, the group of XX true hermaphrodites and the group of XX males had mean levels of the antigen not significantly different from that in normal male controls. Female parents of sex-reversed dogs and some of their female siblings were typed H-Y antigen positive, but the mean level of the antigen in this group was less than that of normal male controls.It is proposed that XX sex reversal in cocker spaniels is due to a mutant gene which when homozygous in females, results in a level of H-Y antigen similar to that found in normal males and the gonads develop as ovotestes or testes. When the gene is heterozygous in females, the level of serologically-detectable H-Y antigen is lowr than that found in normal males and the gonads develop as normal ovaries. The persistence of Mullerian structures in the presence of testicular tissue suggests that Mullerian inhibiting substance is deficient or ineffective in its action in this condition.Supported by NIH Postdoctoral Fellowship IF32 HL05515, University of Pennsylvania Genetics Center Grant, No. GM 20138, and NIH grants AI-19456, HD 17049, and HD 14357; and a grant from the Mrs. Cheever Porter Foundation.     

Loss of Fgfr2 leads to partial XY sex reversal

In mammals, sex is determined in the bipotential embryonic gonad by a balanced network of gene actions which when altered causes disorders of sexual development (DSD, formerly known as intersex). In the XY gonad, presumptive Sertoli cells begin to differentiate when SRY up-regulates SOX9, which in turn activates FGF9 and PGDS to maintain its own expression. This study identifies a new and essential component of FGF signaling in sex determination. Fgfr2 mutant XY mice on a mixed 129/C57BL6 genetic background had either normal testes, or developed ovotestes, with predominantly testicular tissue. However, backcrossing to C57BL6 mice resulted in a wide range of gonadal phenotypes, from hypoplastic testes to ovotestes with predominantly ovarian tissue, similar to Fgf9 knockout mice. Since typical male-specific FGF9-binding to the coelomic epithelium was abolished in Fgfr2 mutant XY gonads, these results suggest that FGFR2 acts as the receptor for FGF9. Pgds and SOX9 remained expressed within the testicular portions of Fgfr2 mutant ovotestes, suggesting that the Prostaglandin pathway acts independently of FGFR2 to maintain SOX9 expression. We could further demonstrate that double-heterozygous Fgfr2/Sox9 knockout mice developed ovotestes, demonstrating that both Fgfr2 and Sox9 can act as modifier intersex genes in the heterozygous state. In summary, we provide evidence that FGFR2 is important for male sex determination in mice, thereby rendering human FGFR2 a candidate gene for unsolved DSD cases such as 10q26 deletions.     

The reproductive performance of XX/XY male chimeric mice

The reproductive performance of male aggregation chimeric mice was examined. C57BL/6 in equilibrium BALB/c male chimeras and control animals, C57BL/6, BALB/c, and their reciprocal F1 crosses, were mated with ICR females. Of 45 overt chimeras, 13 produced mixed-genotype progenies and were revealed to be XY/XY chimeras. By karyotype analysis 16 of 32 single-genotype progeny chimeras were determined to be XX/XY chimeras, but the remaining single-genotype progeny chimeras showed only XY metaphase plates, so that their chromosomal sex could not be determined. The mean litter size of C57BL/6 was significantly higher than that of BALB/c. In contrast, the birth rate of C57BL/6 was lower than that of BALB/c. XY/XY chimeras showed almost the same performance as C57BL/6 for litter size and as BALB/c for birth rate. There were no significant differences for both traits between the reciprocal F1 crosses and XY/XY chimeras. The mean litter size of XX/XY chimeras was lower than that of XY/XY chimeras and the differences was statistically significant. Some XX/XY chimeras had very small testes, while XY/XY chimeras had normal testes. Such results indicate that the reproductive performance of XX/XY male chimeras is inferior to that of XY/XY males.     

Testes of XX ↔ XY chimeric mice develop from fetal ovotestes

The majority of XX ? XY chimeric mice develop into fertile males. The sexual differentiation of the gonads in these animals has been examined on days 12–14 postcoitum to determine if their development parallels that of normal testes. It was found that 50% of chimeric fetuses, the proportion predicted to be XX ? XY, had neither normal testes nor ovaries. Instead, ovotestes were present, with varying proportions of presumptive ovarian and testicular tissue. On day 12 the ovotestes were organized with testicular tissue in the central region and ovarian tissue at the craniad and/or caudad poles. In the more advanced fetuses there was evidence of regression of the ovarian portion, which would account for the testes found in adults. These results are discussed in light of current theories of sex determination and differentiation and what was previously known about gonads of sex mosaics.     

Experimentally induced true hermaphroditism in genetically female fowl

Summary Two types of hermaphroditism were experimentally induced in genetically female fowls by grafting of embryonic testes in embryos. Of the 27 hermaphrodites observed during the 8 months after hatching, 20 possessed a right testis and a left ovary and 7 a right testis and a left ovotestis. The testes and ovotestes contained seminiferous tubules with a more or less developed germ cell complement, attaining in many cases the early spermatid stage. The interstitial tissue was poorly functional, as shown by the absence of male secondary sex characters. The ovary or ovarian part of the ovotestes possessed numerous small ovarian follicles. The female arrangement of the plumage and the absence of spurs demonstrated the secretion of oestrogens. A mechanism is proposed for explaining this partial masculinization of genetically female gonads, a phenomenon which occurs during the period of embryonic sex differentiation, and is responsible for this experimental true hermaphroditism.     

Fast and easy detection of mouse sex chimeras using electrophoretic polymorphism of phosphoglycerate kinase-1, an X chromosome-linked enzyme

About half of the chimeras produced by aggregation of two mouse embryos are sex chimeras composed of both XX and XY cells. We developed a fast and easy method to identify sex chimeras by using electrophoretic bimorphism of an X-linked enzyme, phosphoglycerate kinase-1 (PGK-1), as a marker. When embryos resulting from the crossing of a Pgk-1b/Pgk-1b female and a Pgk-1a/Y male are aggregated, the genotype of sex chimeras is Pgk-1b/Pgk-1a----Pgk-1b/Y. Most of these were identifiable from the PGK-1 electrophoretic pattern of blood cells (i.e., AB type) and the appearance of genitalia (male type or apparently abnormal). Genotypes of functional sperm in the testes of the male-type sex chimeras were also identifiable from the PGK-1 electrophoretic pattern of progenies. Examination of gonads of the sex chimeras revealed that a considerable proportion was hermaphorditic. With this method, reasonable numbers of male-type sex chimeras and hermaphrodites may be selected and used as material for investigating sexual differentiation.     

SRY protein is expressed in ovotestis and streak gonads from human sex-reversal

In mammals, a master gene located on the Y chromosome, the testis-determining gene SRY, controls sex determination. SRY protein is expressed in the genital ridge before testis determination, and in the testis it is expressed in Sertoli and germ cells. Completely sex-reversed patients are classified as either 46,XX males or 46,XY females. SRY mutations have been described in only 15% of patients with 46,XY complete or partial gonadal dysgenesis. However, although incomplete or partial sex-reversal affects 46,XX true hermaphrodites, 46,XY gonadal dysgenesis, and 46,XX/46,XY mosaicism, only 15% of the 46,XX true hermaphrodites analyzed have the SRY gene. Here, we demonstrate that the SRY protein is expressed in the tubules of streak gonads and rete testis, indicating that the SRY protein is normally expressed early during testis determination. Based on these results, we propose that some factors downstream from SRY may be mutated in these 46,XY sex-reversal patients. We have also analyzed SRY protein expression in the ovotestis from 46,XX true hermaphrodites and 46,XX/46,XY mosaicism, demonstrating SRY protein expression in both testicular and ovarian portions in these patients. This suggests that the SRY protein does not inhibit ovary development. These results confirm that other factors are needed for complete testis development, in particular, those downstream of the SRY protein.     

Accidental X-Y recombination and the aetiology of XX males and true hermaphrodites

Accidental recombination between the differential segments of the X and Y chromosomes in man occasionally allows transfer of Y-linked sequences to the X chromosome leading to testis differentiation in so-called XX males. Loss of the same sequences by X-Y interchange allows female differentiation in a small proportion of individuals with XY gonadal dysgenesis. A candidate gene responsible for primary sex determination has recently been cloned from within this part of the Y chromosome by Page and his colleagues. The observation that a homologue of this gene is present on the short arm of the X chromosome and is subject to X-inactivation, raises the intriguing possibility that sex determination in man is a quantitative trait. Males have two active doses of the gonad determining gene, and females have one dose. This hypothesis has been tested in a series of XX males, XY females and XX true hermaphrodites by using a genomic probe, CMPXY1, obtained by probing a Y-specific DNA library with synthetic oligonucleotides based on the predicted amino-acid sequence of the sex-determining protein. The findings in most cases are consistent with the hypothesis of homologous gonad-determining genes, GDX and GDY, carried by the X and Y chromosomes respectively. It is postulated that in sporadic or familial XX true hermaphrodites one of the GDX loci escapes X-inactivation because of mutation or chromosomal rearrangement, resulting in mosaicism for testis and ovary-determining cell lines in somatic cells. Y-negative XX males belong to the same clinical spectrum as XX true hermaphrodites, and gonadal dysgenesis in some XY females may be due to sporadic or familial mutations of GDX.     

Linkage to CFA29 detected in a genome-wide linkage screen of a canine pedigree segregating Sry-negative XX sex reversal

Canine Sry-negative XX sex reversal is a disorder of gonadal development wherein individuals having a female karyotype develop testes or ovotestes. In this study, linkage mapping was undertaken in a pedigree derived from one proven carrier American cocker spaniel founder male and beagle females. All affected dogs in the analysis were XX true hermaphrodites and confirmed to be Sry negative by polymerase chain reaction. A genome-wide linkage screen conducted using 245 microsatellite markers revealed highest LOD score of 3.4 (marker CPH9) on CFA29. Fine mapping with additional microsatellites in the region containing CPH9 localized the Sry-negative XX sex reversal locus to a 5.4-Mb candidate region between markers CPH9 and FH3003 (LOD score 3.15). Insignificant LOD scores were found at genome-wide screen or fine mapping markers that were within 10 Mb of 45 potential candidate genes reported to have a role in mammalian sex determination or differentiation. Together, these results suggest that a novel locus on CFA29 may be responsible for sex reversal in this pedigree.     

Androdioecy and hermaphroditism in five species of clam shrimps (Crustacea: Branchiopoda: Spinicaudata) from India and Thailand

Crustaceans in the order Spinicaudata display a broad range of reproductive strategies, ranging from pure hermaphroditism to pure dioecy (separate males and females), and intermediate combinations. One particularly interesting genus of these “clam shrimps” is Eulimnadia. Based on offspring sex ratios, it has been suggested that all members of the genus are androdioecious: populations consist of mixtures of males and hermaphrodites. However, only two of the ~40 species in this genus have been examined histologically to confirm the presence of ovotestes in the purported hermaphrodites of this group. Here, we report both sex ratio and histological evidence showing that populations of five additional Eulimnadia species from India and Thailand are indeed mixes of males and hermaphrodites (four species) or hermaphrodite only (one species). Sex ratios of adults and offspring from isolated hermaphrodites are in accordance with those previously reported for 15 Eulimnadia species, and histological assays of four of the five species show the presence of both testicular and ovarian tissue in these hermaphrodites. As has been previously reported, the testicular tissue in members of these Eulimnadia spp. is located in a small section at the distal end of the gonad. In addition, the sperm produced in these hermaphrodites forms distinct plaques of compacted chromatin. Overall, these data are consistent with a single origin of hermaphroditism in Eulimnadia, and support the notion that all members of the genus are either androdioecious or all‐hermaphroditic.     

Testes of XX in equilibrium with XY chimeric mice develop from fetal ovotestes

The majority of XX in equilibrium with XY chimeric mice develop into fertile males. The sexual differentiation of the gonads in these animals has been examined on days 12-14 postocoitum to determine if their development parallels that of normal testes. It was found that 50% of chimeric fetuses, the proportion predicted to be XX in equilibrium with XY, had neither normal testes nor ovaries. Instead, ovotestes were present, with varying proportions of presumptive ovarian and testicular tissue. On day 12 the ovotestes were organized with testicular tissue in the central region and ovarian tissue at the craniad and/or caudad poles. In the more advanced fetuses there was evidence of regression of the ovarian portion, which would account for the testes found in adults. These results are discussed in light of current theories of sex determination and differentiation and what was previously known about gonads of sex mosaics.     

Three cases of sex chromosome mosaicism with a nonfluorescent Y

Summary Clinical and cytogenetic findings in three patients mosaic for sex chromosomes (45,X0/46,XY; 45,X0/46,XY/46,XYq-, and 45,X0/46,XY/46,XYY), each with a nonfluorescent Y, are presented. Hypotheses for the origin and effect of these chromosome constitutions are discussed.