The identification of human H-Y antigen and testicular transformation induced by its interaction with the receptor site of bovine fetal ovarian cells

Uterine tumor resembling ovarian sex cord tumor: report of a case with t(X;6)(p22.3;q23.1) and t(4;18)(q21.1;q21.3)

Uterine tumor resembling ovarian sex cord tumor (UTROSCT) is a rare tumor of reproductive-age and postmenopausal women. We present the first case of UTROSCT with cytogenetic analysis. The tumor occurred in a 34-year-old woman who presented with menorrhagia and a uterine mass. Histologic examination showed tumor with features of sex cord-like epithelium and abundant fibromuscular stroma without an endometrial stromal sarcoma component. The tumor cells expressed cytokeratin, CD99, vimentin, desmin, smooth muscle actin, and estrogen and progesterone receptors. The majority of the cells analyzed by cytogenetic studies showed two balanced chromosomal translocations: t(X;6)(p22.3;q23.1) and t(4;18)(q21.1;q21.3). Several known tumor-related genes (bcl-2, MALT-1, FVT1, SCCA1, SCCA2, and DCC at 18q21; RAP1 at 4q21; and STL at 6q23) and a gonadal-development related gene (H-Y regulator gene at Xp22.3) are located at or near the translocation breakpoints. The tumor cells of sex cord-like elements were strongly and diffusely immunoreactive for bcl-2 antibody. These cytogenetic and immunohistochemical data may suggest potential molecular mechanisms of tumorigenesis of UTROSCT.

Procedures for Sxs antigen detection by antibody-mediated cytotoxicity tests. A comparative analysis

Biological reagents used in the serological detection of Sxs antigen by antibody-mediated cytotoxicity tests were compared in order to optimize the method. Our analyses showed that: (a) red cell-free spleen cells are the best target cells, (b) rabbit serum used as the complement source should be obtained from females, and absorbed with female spleen cells before use, (c) antiserum obtained by immunizing females with repeated injections of syngenic male spleen cells provides the highest anti-Sxs antibody titer, and (d) of the different biological fluids investigated, testis supernatant has highest concentration of Sxs antigen.

The production of anti-H-Y monoclonal antibodies: their potential use in a sex test for bovine embryos

In an attempt to improve the accuracy of sexing bovine embryos, new anti-H-Y monoclonal antibodies were produced and selected, using an extended screening procedure. In addition to the commonly used screening of soluble H-Y antigen sources, such as testis supernatant and Daudi supernatant, the binding specificity to cell surface H-Y antigen was tested also. A radioimmunoassay (RIA) employing male and, as a control, female bovine lymphocytes, and enzyme-linked immunosorbent assays (ELISAs) on solubilized membrane fractions resulted in the selection of a number of clones producing monoclonal antibody (mAb) with male-enhanced binding. Four of the anti-H-Y mAb were assessed for binding to Day 7 or 8 bovine embryos. The accuracy of sexing bovine embryos ranged from 58% to 71%. Two of the four antibodies did not react with presumed soluble H-Y antigen-containing sources in an ELISA. These results raise doubts about the suitability of the presumed soluble H-Y antigen sources, Daudi, TM4 and testis supernatant, to be used in screening tests for anti-H-Y antibodies.

A substance secreted by rat Sertoli cells induces feminization of embryonic chick testes in vitro

Male and female gonads from 7- to 9-day-old chick embryos were cultured for 6 days in Sertoli cell-conditioned medium or in serum-free medium to investigate the possible effect of substances secreted by rat Sertoli cells on chick gonad development. Histological analysis showed that whereas all female gonads proceed through normal ovarian development in both culture media, most of male gonads showed clear feminization only when cultured in Sertoli cell-conditioned medium; male gonads cultured in serum-free medium developed as normal testes. Because the only substance detected in our conditioned medium with the potential to cause these effects was sex-specific antigen (Sxs), our results provide further evidence that Sxs antigen may play a role in sexual differentiation in birds, and probably in mammals.

Daudi supernatant, unlike other H-Y antigen sources, exerts a sex-reversing effect on embryonic chick gonad differentiation

In vitro cultures of intact chick gonads (organ cultures) and reaggregation cultures of dispersed gonad cells (roller cultures) were made. Gonads or gonad cells from 7-day-old chick embryos, at the stage when sex-specific differentiation begins, were cultured in the presence of presumed H-Y antigen-containing supernatants, or co-cultured in the presence of H-Y antigen-producing cell lines. The H-Y antigen-producing cells tested were of human, mouse, bovine and chicken origin. During organ culture, addition of supernatant of the human lymphoma cell line Daudi, or co-culture with Daudi cells, stimulated a clear proliferation of the germinal epithelium in male gonads, indicating feminization. A similar effect was obtained by treatment with estradiol. In reaggregation culture, the increase in nuclear size of germ cells was chosen as a parameter for feminization. A significant increase of germ cell nuclear size was observed in gonads cultured in the presence of Daudi supernatant. In both organ cultures and reaggregation cultures, other tested H-Y antigen sources and semi-purified H-Y antigen fractions did not exert significant effects on differentiation of the gonads or on the average area of the germ cell nuclei. These findings suggest that it is not H-Y antigen, but another protein produced by Daudi cells, that might be responsible for the sex-reversing effects.

Evaluation of a solid-phase cellular enzyme immunoassay for detection of the serologically defined male antigen

An indirect cellular enzyme immunoassay for the detection of the serologically defined male-specific antigen, SDMA, was developed using mouse spermatozoa as the target. Serum from B6 female mice injected with male spleen cells was used as the source of SDMA-specific antibody. Our results indicate that the assay is highly reliable (96% accurate) with an intra- and interassay coefficient of variation less than 12%. Since this assay is non-subjective and simple to perform it provides a useful alternative to the complement-dependent cytotoxicity assay for detection of SDMA.

Gonadal differentiation: a review of the physiological process and influencing factors based on recent experimental evidence

The sexual differentiation of a gonad is determined in normal embryology by the presence or absence of the TDF gene, a short segment of DNA localized near the tip of the short arm of the Y chromosome. Under the stimulus of this gene, the somatic cells of the genital ridge differentiate into Sertoli cells and secrete anti-müllerian hormone. This hormone inhibits the germ cells from entering meiosis and may well also trigger the formation of the primary sex cords. Once the Sertoli cells are formed, further differentiation of the gonad is independent of the TDF presence, although this gene may further contribute to the normal functioning of the male gonad. In true hermaphroditism the normal regulation of the gonadal differentiation is missing. Gonadal differentiation may revert to a more primitive evolutionary level at which the rate of growth of the gonad determines its sexual direction. When this exceeds a certain threshold a testis may develop despite the absence of the TDF gene.

Production and characterization of monoclonal antibodies against the H-Y antigen

Monoclonal antibodies against the H-Y antigen were produced using spleen cells from female C57BL/6 mice hyperimmunized with cells from syngeneic males. Anti-H-Y positive clones were detected by enzyme immunoassays. Supernatant fluids from Daudi cell cultures and testicular cell preparations taken from mice, rabbits or calves served as presumptive sources of H-Y antigen. In addition, testis supernatant from genetically sterile mice was used. Male specificity was ascertained by the fact that the antibodies could be absorbed with spleen cells from male but not from female mice. Binding of the antibodies to H-Y antigen on the surface of male and female cells, obtained from a number of tissues and species, was confirmed by an indirect immunofluorescence assay. Several monoclonal antibodies appeared to be positive in all assays tested, suggesting that the molecule conferring the H-Y antigenicity lacks species-specificity and appears to be identical for soluble and membrane-bound H-Y antigen.

Immunoprecipitation of a male-specific polypeptide after in vitro translation of testicular poly(A)+ RNA

Poly(A)+ RNAs from male and female gonads of 20-day-old rats were translated in vitro using rabbit reticulocyte lysates. The resulting polypeptides were incubated with specific anti-male (anti-H-Y) antisera raised in female rats by intrasplenic immunization with syngeneic male skin. Using a second antibody, a male-specific polypeptide of molecular weight approximately 18,000 was immunoprecipitated. This male-specific polypeptide was not cotranslationally modified in vitro and appeared to be identical to serological H-Y antigen.

Reaction of monoclonal H-Y antibody in the ELISA

Monoclonal H-Y antibody of demonstrated specificity was reacted with soluble H-Y antigen in a newly-developed enzyme-linked immunosorbent assay (ELISA). Typing of cell lines was accomplished by qualitative and quantitative absorption. In one case, the antibody was subdivided into equal portions, each of which was absorbed with 1, 3, 6 or 12 X 10(6) cells from male or female; after absorption, the cells were discarded and the antibody was titrated for residual activity in the ELISA. With increasing cell numbers, optical density scores for male-absorbed antibody approached baseline levels. Although male-female differences were pronounced and highly significant, there was also a fall in reactivity after absorption with female cells.

46,XY gonadal dysgenesis: is oncogenesis related to H-Y phenotype or breast development?

Among women with 46,XY gonadal dysgenesis, there is a high incidence of gonadal tumors. Because of evidence of a connection between occurrence of those tumors, H-Y phenotype, and breast development, we surveyed 55 cases of 46,XY gonadal dysgenesis and 12 related cases involving chromosomal and/or skeletal abnormalities. Our survey, including three new cases presented here, indicates that H-Y phenotype but not breast development may be related to the development of the gonadoblastoma-dysgerminoma. Thus among women with 46,XY gonadal dysgenesis, there are H-Y- and H-Y+ classes, but gonadal tumors are found almost exclusively in the H-Y+ class. Yet one of our patients may represent an exception to the association of H-Y+ phenotype and gonadal tumors in this syndrome.

Detection of H-Y in the enzyme-linked immunosorbent assay

We have developed a new enzyme-linked immunosorbent assay for determination of H-Y phenotype in the human. This assay, which measures the inhibition of the reaction of a monoclonal anti-H-Y antibody and a mouse testis extract as a source of H-Y antigen, was applied to the supernatant of lymphocytes from ten normal male and ten normal female subjects. Introduction of supernatant from male cells gave readings of 69%-78% of those obtained with testis supernatant alone; female-cell supernatant did not inhibit the reaction (89%-102%).

Free H-Y antigen induces in vitro testicular differentiation of human XX embryonic indifferent gonads

In accordance with the anchorage site hypothesis, Daudi beta 2-microglobulin (-) HLA (-) human male Burkitt lymphoma cells are incapable of stably maintaining H-Y antigen on their plasma membrane; instead, they excrete it into the culture medium. The proposed testis-organizing function of Daudi H-Y antigen in solution, previously demonstrated in bovine ovarian embryonic cells, has been tested for the first time in human undifferentiated gonads. Cultured in the presence of Daudi excreted H-Y antigen, gonads obtained from early human embryos of 46, XX chromosomal constitution underwent precocious and complete testicular differentiation.

Fetal H-Y typing using human amniotic fluid

The H-Y (male) antigen is phylogenetically conserved among vertebrate species, including the species man. Previous studies have indicated the presence of a "soluble" H-Y antigen in male serum and culture fluids of male cells. We examined over 50 samples of amniotic fluid from male and female fetuses to determine if H-Y typing could be correlated with the sex of the fetus. Samples of amniotic fluid were tested to inhibit the reactivity of monoclonal antibodies in a standard H-Y assay with protein A sheep red blood cells. We found that amniotic fluids from male fetuses inhibited 40% of the reactivity and that amniotic fluids from female fetuses inhibited 0.5% of reactivity. We could also correctly identify the sex of 90% of male fetuses and 100% of female fetuses. We have not yet identified the exact nature of the inhibiting antigen(s) in the amniotic fluids, but our results clearly indicate the feasibility of fetal H-Y typing.

H-Y antigen in the chicken

To determine whether asymmetrical development of the chicken ovary could be related to differential expression or function of H-Y antigen, the putative ZW ovary inducer, we compared the ability of cells from the left and right gonad to absorb H-Y antibodies in 17-day chick embryos and in one-day-old hatchlings. In addition, we studied uptake of soluble H-Y antigen by gonadal cells in 17-day embryos, one-day-old hatchlings, and young adults. Indications are that H-Y is present in the left gonad of the female, and to a lesser extent in the right, and not in the testes of the male. Our preliminary results indicate moreover that the right ZW gonad may lack receptor sites for soluble H-Y at around the time of hatching. It may be inferred that expression of H-Y antigen is a prerequisite of ovarian development in birds, although it remains to be determined unambiguously whether H-Y is the primary inducer of the ZW gonad or an accessory molecule involved in some intermediate aspect of gonadal development.

The absence of specific interactions of Sertoli-cell-secreted proteins with antibodies directed against H-Y antigen

Radiolabeled proteins secreted into the medium by rat Sertoli cells in primary culture have been examined for specific interactions with polyclonal and monoclonal antibodies directed against serologically detectable H-Y antigen(s). None of the proteins secreted by Sertoli cells reacted specifically with H-Y antibodies, as determined with immunoprecipitation procedures and immunoabsorbent affinity chromatography, followed by SDS gel electrophoresis. Radioactivity profiles of proteins obtained after reaction with H-Y antibodies were similar to those observed after treatment with nonimmune sera or with irrelevant antibodies. We obtained comparable findings with proteins secreted by the mouse cell line TM4, which is of presumptive Sertoli cell origin, and with proteins present in ram rete testis fluid. These and other findings presented do not support the contention that Sertoli cells secrete a protein having the properties of serologically detectable H-Y antigen as previously described.

H-Y antigen expression in patients with X-autosomal translocations and gonadal dysgenesis

Cells from three patients with early gonadal failure and a balanced reciprocal translocation involving the long arm of the X chromosome and an autosome were studied. Fibroblasts from a patient with a similar balanced reciprocal translocation but normal reproductive capabilities were also studied. Two of the four patients were found to have serologically detectable H-Y antigen on their cells. Since H-Y antigen has been found on the cells of other patients with X chromosome abnormalities but without a Y chromosome, it is thought that the X chromosome plays a role in the regulation of H-Y antigen expression. This study suggests that the long arm of the X chromosome may be involved but the location of a regulatory gene cannot be identified in these studies. These cases do not permit us to implicate H-Y antigen as a cause of gonadal dysgenesis and early gonadal failure in females who have structurally abnormal X chromosomes.

Effects of H--Y antigen on morphologic and endocrine differentiation of gonads in mammals

The effects of H--Y antigen, released in a soluble state by male human Burkitt lymphomas and mouse teratomas, were studied in the fetal gonads from 13 to 21-day-old rats and 98-day-old calves, using histologic techniques, radioimmunoassays for testosterone, and bioassays for Müllerian-inhibiting substance (MIS). Whereas no effect was detected in the younger gonads, some structural changes were observed in bovine and 21-day-old rat ovaries when cultured for 5 days with Daudi and male teratoma supernatants, but there was no synthesis of testosterone or MIS. These observations raise questions concerning the critical period of sensitivity to H--Y antigen of female gonads, and the dissociation between morphologic and biochemical events.

X-linked genes of the H-Y antigen system in the wood lemming (Myopus schisticolor)

H-Y antigen was investigated in 18 specimens representing six different sex chromosome constitutions of the wood lemming (Myopus schisticolor). The control range of H-Y antigen was defined by the sex difference between normal XX females (H-Y negative per definitionem) and normal XY males (H-Y positive, full titer). H-Y antigen titers of the X*Y and X*0 females were in the male control range, while in the X*X and X0 females the titers were intermediary. Data were obtained with two different H-Y antigen assays: the Raji cell cytotoxicity test and the peroxidase-antiperoxidase (PAP) method. Fibroblasts, gonadal cells, and spleen cells were checked. Presence of full titers of H-Y antigen in the absence of testis differentiation is readily explained by the assumption of a deficiency of the gonad-specific receptor of H-Y antigen. Since sex reversal is inherited as an X-linked trait, genes for this receptor are most likely X-linked. The implications of our findings are discussed in connection with earlier findings concerning H-Y antigen in XY gonadal dysgenesis in man and the X0 situation in man and mouse.

An oocyte-specific antigen and its possible role in the organization of the ovarian follicle of the rat

An oocyte-specific antigen was detected by an antiserum produced in isogenic Lewis rats. The antigen was sensitive to trypsin treatment. Dissociation-reorganization experiments in vitro, using ovarian cells demonstrated that the antigen is required for the interaction of germ cells and somatic cells. A physiologic role is suggested for this differentiation antigen in follicular morphogenesis and ovarian function.

Effects of maternal anti H-Y antibodies on fetal gonadal development

C57BL/6 inbred female mice preimmunized by serial injections of isogeneic male spleen cells were mated and the effects of the circulating anti H-Y antibodies on the fetal gonads and on their fertility were studied. Female mice receiving injections of saline formed one control group and those given female spleen cells a second control group. The experiment was carried out three times and since observations were similar and reproducible the data of all three sets were pooled. There was no significant change in the birth weights of newborns, total number of conceptions or sex ratio in the study group compared to either of the controls. There was no difference in the mean live birth rate between the study group and both the controls. Although the incidence of stillbirths in the study group was higher than that in both controls the difference was not statistically significant. In the study group there were no histopathological changes in the gonads from female pups compared to ovaries from the controls. In contrast, the gonads of male pups showed mild to severe structural disorganization in the study group, but not in the female spleen cell injected group. In spite of the morphological changes in the testes, the newborn male pups had a normal anogenital distance and testicular descent suggesting that Leydig cell function was normal.

H-Y and antigens of the major histocompatibility complex. H-Y and H-2D antigens are associated on unfixed lymphocytes and thymocytes but not on testicular cells

The results of an antibody blocking technique indicate that H-Y and H-2D antigens are close to one another on the surfaces of unfixed thymocytes and lymphocytes, but distant on testicular cells. The findings are the same using cells from mice of several inbred strains (C57BL/10, BALB/c, b6.H-2k). The data indicate moreover that H-2K antigens and H-Y are distant on all cell types tested. The gonad specific H-Y receptor-presumed necessary for H-Y directed testicular differentiation is associated with neither H-2D nor H-2K antigens.

Cell reorganization in vitro of heterosexual gonadal cocultures

Male and female gonadal cells of newborn rats were cocultured in varying proportions. As low a proportion as 20% of male cells essentially yielded tubular structures. At lower quotas of testicular cells, however, only follicular structures occurred. Mixed structures were not observed except one experiment (20% male cells). When ovarian cells were cocultivated with male nongonadal cells, no conversion occurred. It is assumed that H-Y antigen secreted by male gonadal cells is bound by the ovarian receptor sites and induces conversion into tubular structures. H-Y antigen integrated into the cell membrane of nongonadal male cells does not seem to be able to exert this morphogenetic effect.

H-Y antigen negative germ cells in gonadal sex organization in vitro: a morphological study

Dissociation-reorganization experiments were done with gonadal cells of newborn rats. Rotation cultures consisted of mixtures of somatic and germ cells of opposite sex. Somatic cells, ovarian or testicular, determined a female or male type respectively, of gonadal histomorphic organization. Germ cells did not affect the type of organization of somatic cells. Accordingly, suspensions containing somatic cells of one sex together with germ cells of both sexes, reorganized in rotation culture, into either a) follicles containing XX or XY germ cells, or b) tubules containing XX or XY or both types of germ cells. These results give morphological evidence for heterosexual germ-somatic cells interactions. Based on morphological and H-Y antigen studies, failure of germ cells to bind and express H-Y antigen is considered as a possible factor for this failure of germ cells to affect gonadal sex.

Mechanisms of gonadal differentiation

Sex differentiation is the result of the translation of genetic sex into gonadal sex. Without recognizable masculinizing signals the embryonic gonad will undergo ovarian differentiation. The main determinant of gonadal differentiation appears to be the presence or absence of a cell surface antigen, called H-Y antigen. The regulation of H-Y antigen expression is complex and involves the interaction between regulatory sites on the Y chromosome, the X chromosome, and possibly the autosomes.

Mammalian cross-reactive H-Y antigen induces sex reversal in vitro in the avian testis

Testes of either newborn rats or newly hatched chickens, dissociated into single cell suspensions, reorganize in vitro into their histotypic structures. In birds, the heterogametic female sex is H-Y antigen positive, and not the male as in mammals. Cocultivation of rat and chicken testicular cells results in the reorganization of an ovotestis. A similar result is obtained after cultivation of chicken testicular cells in the supernatant medium of cultured human male Burkitt lymphoma Daudi cells. Rat testicular Sertoli cells as well as Daudi cells are a source of H-Y antigen. The simultaneous application of H-Y antigen and anti-H-Y antiserum prevents ovotestis formation. It is concluded that H-Y antigen which is known to be testis-organizing in mammals, is the ovary-organizing factor in birds.

Differential expression of minor histocompatibiility antigens on the surface of the mouse oocyte and preimplantation developmental stages

The expression of specific minor histocompatibility antigens on oocytes and preimplantation developmental stages in the mouse has been examined using immunofluorescence. Multi-specific alloantisera in conjunction with serological adsorption and target cells of the appropriate genotype have been used to how that there is differential expression of minor histocompatibility antigens during early development. Detailed analysis showed that antigen expression can be detected on oocytes and zygotes, but not on two-cell stages. From the eight-cell stage to the blastocyst, reactivity with antibody directed against a single specificity could be detected.

Phenotypic conversion of human erythrocytes by H-Y antigen

Human male erythrocytes absorb H-Y antiserum while those of human females do not. Studies on the mode of attachment of H-Y antigen to the erythrocyte membrane reveal: (1) After several washes H-Y antigen can only be removed from male erythrocytes and not from other male cells such as granulocytes. (2) Female erythrocytes absorb exogenous H-Y antigen and thus become H-Y positive. (3) Complement mediated lysis of erythrocytes by H-Y antiserum is not sex specific but is dependent on the ABO blood group type of the red blood cells. It is concluded that H-Y antigen is unspecifically attached to red blood cells and is therefore not an integral part of the erythrocyte membrane.

H-Y antigen in X,i(Xq) gonadal dysgenesis: evidence of X-linked genes in testicular differentiation

Three years ago, we detected H-Y antigen in the white blood cells of a phenotypic female with several of the stigmata of Turner's syndrome, and the mosaic karyotype: 45,X/46,X,i(Xq). We surmised at the time that the isochromosome, i(Xq), may have contained occult Y-Chromosome-derived material. We have now confirmed the presence of H-Y in this patient and we have obtained evidence for the presence of H-Y in four of five other similar patients, all of whom are notable for carrying at least a single cell line with the karyotype 46,Xi(Xq). Although we cannot categorically exclude the presence of Y-chromosomal genes in the cells of these patients, there is no cytogenetic evidence of structural rearrangement involving the Y in any of the cases. Expression of H-Y structural genes are X-situated, or alternatively that they are autosomal and X-regulated. It would follow that the H-Y+ cellular phenotype per se is not a valid marker for the Y-chromosome, and that H-Y genes that have been mapped to the pericentric region of the Y may be regulatory.

H-Y antigen in transsexuality, and how to explain testis differentiation in H-Y antigen-negative males and ovary differentiation in H-Y antigen-positive females

H-Y antigen was determined in eight transsexual patients. Two of the four male-to-female transsexual patients typed as H-Y antigen-negative, while the other two typed as expected from their phenotypic and gonadal sex, namely H-Y antigen-positive. Of the four female-to-male transsexual patients, three typed as H-Y antigen-positive and one was H-Y antigen-negative, as expected. The presence of normal testes in H-Y antigen-negative males is assumed to result from a mutation of nucleotide sequences of the H-Y structural gene for antigenic determinants. Thus, an H-Y is produced with normal receptor-binding activity which can sustain the testis determination of the bipotent gonadal anlage. In the case of H-Y antigen-positive females with normal ovaries a deletion of the autosomally located H-Y structural gene is assumed. This deletion should affect sequences for repressor-binding (as was suggested for H-Y antigen-positive XX-males) and for receptor-binding activity of the H-Y antigen molecule. The resulting H-Y antigen is unable to bind to the gonadal receptor of the bipotent gonadal anlage. Thus an ovary is determined. The relevance of H-Y antigen for the aetiology of transsexualism is discussed.

Female phenotype and multiple abnormalities in sibs with a Y chromosome and partial X chromosome duplication: H--Y antigen and Xg blood group findings

A mentally retarded female child with multiple congenital abnormalities had an abnormal X chromosome and a Y chromosome; the karyotype was interpreted as 46,dup(X)(p21 leads to pter)Y. Prenatal chromosome studies in a later pregnancy indicated the same chromosomal abnormality in the fetus. The fetus and proband had normal female genitalia and ovarian tissue. H--Y antigen was virtually absent in both sibs, a finding consistent with the view that testis-determining genes of the Y chromosome may be suppressed by regulatory elements of the X. The abnormal X chromosome was present in the mother, the maternal grandmother, and a female sib: all were phenotypically normal and showed the karyotype 46,Xdup(X)(p21 leads to pter) with non-random inactivation of the abnormal X. Anomalous segregation of the Xga allele suggests that the Xg locus was involved in the inactivation process or that crossing-over at meiosis occurred.

H-Y antigen in 46,XY gonadal dysgenesis

Presence of H-Y antigen has been correlated with testicular differentiation, and absence of H-Y with failure of testicular differentiation, in a variety of mammalian species. To determine more precisely the relationship between expression of H-Y antigen and development of the testis, we studied the cells of phenotypic females with the 46,XY male karyotype. Blood leukocytes were typed H-Y+ in five XY females with gonadal dysgenesis, although in other studies blood leukocytes from XY females with gonadal dysgenesis were typed H-Y-. Thus mere presence of H-Y antigen is not sufficient to guarantee normal differentiation of the testis. In the present paper we review evidence for an additional factor in gonadal organogenesis, the H-Y antigen receptor. We infer that testicular development requires engagement of H-Y and its receptor. It follows that XY gonadal dysgenesis is the consequence of functional absence of the H-Y testis inducer as in the following conditions: failure of synthesis of H-Y or failure of specific binding of H-Y.

Expression of H-Y antigen in the guppy (Lebistes reticulatus)

Expression of a mammalian cross-reactive H-Y antigen on the surface of cells derived from the male guppy ((Lebistes reticulatus) is demonstrated. This finding further establishes the evolutionary conservation of H-Y antigen among lower vertebrates and provides a basis for speculation on the possible evolutionary association between H-Y antigen and sex determination.