Mullerian inhibiting substance in human testes after birth

Müllerian inhibiting substance/anti-Müllerian hormone: A novel treatment for gynecologic tumors

Müllerian inhibiting substance (MIS), also called anti-Müllerian hormone (AMH), is a member of the transforming growth factor-β super-family of growth and differentiation response modifiers. It is produced in immature Sertoli cells in male embryos and binds to MIS/AMH receptors in primordial Müllerian ducts to cause regression of female reproductive structures that are the precursors to the fallopian tubes, the surface epithelium of the ovaries, the uterus, the cervix, and the upper third of the vagina. Because most gynecologic tumors originate from Müllerian duct-derived tissues, and since MIS/AMH causes regression of the Müllerian duct in male embryos, it is expected to inhibit the growth of gynecologic tumors. Purified recombinant human MIS/AMH causes growth inhibition of epithelial ovarian cancer cells and cell lines in vitro and in vitro via MIS receptor-mediated mechanism. Furthermore, several lines of evidence suggest that MIS/AMH inhibits proliferation in tissues and cell lines of other MIS/AMH receptor-expressing gynecologic tumors such as cervical, endometrial, breast, and in endometriosis as well. These findings indicate that bioactive MIS/AMH recombinant protein should be tested in patients against tumors expressing the MIS/AMH receptor complex, perhaps beginning with ovarian cancer because it has the worst prognosis. The molecular tools to identify MIS/AMH receptor expressing ovarian and other cancers are in place, thus, it is possible to select patients for treatment. An MIS/AMH ELISA exists to follow administered doses of MIS/AMH, as well. Clinical trials await the production of sufficient supplies of qualified recombinant human MIS/AMH for this purpose.

Müllerian inhibiting substance/anti-Müllerian hormone: a potential therapeutic agent for human ovarian and other cancers

According to the 2008 American Cancer Society statistics, cancer remains the second leading cause of death in American today. Early detection, innovative surgery, new drugs and increased public education regarding avoidable risk factors, such as smoking, have had significant impact on the incidence and survival rates of many cancers, while overall death rates from all cancers have declined a modest 5% over the past 50 years. Ovarian cancer statistics, however, have not been as encouraging. Despite recent advances in the management of this disease, 5-year survival has not improved, and the search continues for rationally designed new treatments. Müllerian Inhibiting Substance is a strong candidate because it addresses many of the deficiencies of existing treatments. Namely, Müllerian Inhibiting Substance has little demonstrated toxicity, it complements the activity of known anticancer drugs, it is highly specific against cancers expressing its receptor and it inhibits the proliferation of drug-resistant tumors.

Molecular mechanisms underlying the activation of mammalian primordial follicles

In humans and other mammalian species, the pool of resting primordial follicles serves as the source of developing follicles and fertilizable ova for the entire length of female reproductive life. One question that has intrigued biologists is: what are the mechanisms controlling the activation of dormant primordial follicles. Studies from previous decades have laid a solid, but yet incomplete, foundation. In recent years, molecular mechanisms underlying follicular activation have become more evident, mainly through the use of genetically modified mouse models. As hypothesized in the 1990s, the pool of primordial follicles is now known to be maintained in a dormant state by various forms of inhibitory machinery, which are provided by several inhibitory signals and molecules. Several recently reported mutant mouse models have shown that a synergistic and coordinated suppression of follicular activation provided by multiple inhibitory molecules is necessary to preserve the dormant follicular pool. Loss of function of any of the inhibitory molecules for follicular activation, including PTEN (phosphatase and tensin homolog deleted on chromosome 10), Foxo3a, p27, and Foxl2, leads to premature and irreversible activation of the primordial follicle pool. Such global activation of the primordial follicle pool leads to the exhaustion of the resting follicle reserve, resulting in premature ovarian failure in mice. In this review, we summarize both historical and recent results on mammalian primordial follicular activation and focus on the up-to-date knowledge of molecular networks controlling this important physiological event. We believe that information obtained from mutant mouse models may also reflect the molecular machinery responsible for follicular activation in humans. These advances may provide a better understanding of human ovarian physiology and pathophysiology for future clinical applications.

A single base pair mutation encoding a premature stop codon in the MIS type II receptor is responsible for canine persistent Müllerian duct syndrome

Müllerian inhibiting substance (MIS), a secreted glycoprotein in the transforming growth factor-beta family of growth factors, mediates regression of the Müllerian ducts during embryonic sex differentiation in males. In persistent Müllerian duct syndrome (PMDS), rather than undergoing involution, the Müllerian ducts persist in males, giving rise to the uterus, fallopian tubes, and upper vagina. Genetic defects in MIS or its receptor (MISRII) have been identified in patients with PMDS. The phenotype in the canine model of PMDS derived from the miniature schnauzer breed is strikingly similar to that of human patients. In this model, PMDS is inherited as a sex-limited autosomal recessive trait. Previous studies indicated that a defect in the MIS receptor or its downstream signaling pathway was likely to be causative of the canine syndrome. In this study, the canine PMDS phenotype and clinical sequelae are described in detail. Affected and unaffected members of this pedigree are genotyped, identifying a single base pair substitution in MISRII that introduces a stop codon in exon 3. The homozygous mutation terminates translation at 80 amino acids, eliminating much of the extracellular domain and the entire transmembrane and intracellular signaling domains. Findings in this model could enable insights to be garnered from correlation of detailed clinical descriptions with molecular defects, which are not otherwise possible in the human syndrome.

The effects of orchiopexy on serum anti-Müllerian hormone levels in unilateral cryptorchid infants

BACKGROUND/PURPOSE

In males, serum anti-Müllerian hormone (AMH) reflects Sertoli cell function and provides an estimate of seminiferous tubular integrity. It has been suggested that comparison of AMH levels before and after surgery could be useful to determine effectiveness of the treatment. In this study, we determined the serum AMH levels in infants with unilateral cryptorchidism before and after orchiopexy procedure and compared these data with the AMH values in age-matched controls.

METHODS

The study population was 20 cryptorchid children with unilateral palpable testes who underwent orchiopexy as a cryptorchid group, and 20 healthy children who underwent circumcision as a control group. All children are 12 months of age. Serum AMH levels were measured at just before surgery (at 12 month old) and 6 months after surgery (at 18 month old).

RESULTS AND CONCLUSIONS

All undescended testes were found to be normal in size and in the superficial inguinal pouch or subcutaneous region of the groin at surgery. With regard to the preoperative serum AMH levels, there was a significant difference between the cryptorchid and the control groups (40.04 +/- 4.97 ng/ml versus 53.46 +/- 7.51 ng/ml) (P < 0.05). Similarly, the postoperative serum AMH levels were lower in cryptorchid children than in controls (39.27 +/- 4.58 ng/ml versus 52.79 +/- 6.27 ng/ml) (P < 0.05). In cryptorchid children, serum AMH levels measured at 6 months after orchiopexy were similar with preoperative basal levels (40.04 +/- 4.97 ng/ml versus 39.27 +/- 4.58 ng/ml) (P > 0.05). AMH levels in children with unilateral palpable undescended testes remain unchanged 6 months after orchiopexy performed at 1 year of age. This is the first report in literature regarding the effect of orchiopexy on the serum AMH levels.

AMH/MIS: what we know already about the gene, the protein and its regulation

(AMH/MIS) was first suggested by Jost, more than Four decades before this gonadal glycoprotein was purified and its gene and promoter sequenced. In mammals, AMH expression is triggered by SOX9 in Sertoli cells at the onset of testicular differentiation, and regulated by SF1, GATA factors, WT1, DAX1 and FSH. Ovarian granulosa cells also secrete AMH from late foetal life. In males, AMH is secreted into the bloodstream at high levels until puberty when it is down-regulated by androgens and meiotic germ cells and its directional secretion switches from the basal compartment to the seminiferous tubule lumen. In birds and reptiles, AMH expression shows particular features. Serum AMH determination is useful to study testicular function in boys and in patients with gonadal tumours. AMH levels in seminal and follicular fluid may also be of clinical use.

A case of transverse testicular ectopia with müllerian duct remnant

Transverse testicular ectopia (TTE) associated with persistent müllerian duct (PMD) is a rare genitourinary anomaly. The authors report a case with a review of the literature and stress the importance of careful physical examination and ultrasonography in making a correct preoperative diagnosis of TTE. One should be careful not to miss the tiny PMD structure at the operation. Transseptal orchidopexy is the surgical treatment of choice.

Aetiology of intersexuality in female (XX) pigs, with novel molecular interpretations

This review considers the problem of ovotestis formation in animals of 38,XX chromosome complement. After a clinical description, attention focuses on the condition of the gonads and genital tract. A complete spectrum of gonadal types has been found, ranging from a single ovotestis almost invariably on the right-hand side to both gonads appearing as testicular-like structures, sometimes with a distinct tunica albuginea. The ovotestis or testis-like structure may have descended to an inguinal or scrotal location. Although interstitial cells of Leydig and seminiferous tubules were always abundant in testicular tissue, germ cells were never present. The lumen of the seminiferous tubules was packed with pale-staining, Sertoli-like cells. A bicornuate uterus was characteristic but suppression of the proximal portion of the Müllerian duct always adjoined an ovotestis; a corresponding development of the Wolffian duct featured as a convoluted epididymis. Inhibition of the Fallopian tube was attributed to a local influence of AMH from the Sertoli cells, as was the failure of small Graafian follicles within an ovotestis to respond to injected gonadotrophins. As to the aetiology of an ovotestis, defective colonisation of the genital ridges by primordial germ cells is considered, as is evidence for incorporation of adrenal cells into the embryonic gonad. Molecular probing has failed to reveal the classical sex-determining gene, Sry, and other Y-related DNA sequences such as Zfy and DYZI in almost all the intersex animals examined. Currently favoured as an explanation for ovotestis formation is a mutation in the inhibin gene within granulosa cells of Graafian follicles. Such a mutation would prompt secretion of the closely comparable glycoprotein molecule AMH in these genetic females, with a resultant progressive virilisation of gonadal tissue. The proposed mutation may be carried as an autosomal recessive gene by certain boars. Varying amounts of AMH secretion or differing timescales for the transition from inhibin to AMH could in part explain differing degrees of ovotestis formation. Despite this proposition, interactions between genes that prescribe functional testicular tissue, enhanced rates of gonadal development, and left-right asymmetries between the paired gonads now require systematic study.

Human chorionic gonadotropin (hCG) fails to stimulate gonocyte differentiation in newborn mouse testes in organ culture

The primitive germ cells within the postnatal testis differentiate through several steps to form primary spermatocytes, which are required for postpubertal spermatogenesis. It is postulated that this germ cell development is controlled by the hypothalamic-pituitary-gonadal axis. To study the effect of human chorionic gonadotropin (hCG) on postnatal testicular germ cell differentiation, especially on gonocytes, newborn mouse testes (n = 75) were cultured for 7 days in vitro. The synthetic serum-free medium contained either hCG or exogenous human recombinant müllerian inhibiting substance (MIS) plus transferrin, insulin and retinoic acid (TIRA). Fetal calf serum 10% (FCS) was used for control medium. Thirty-eight newborn mouse testes were cultured with hCG (0.1 to 2.0 IU/ml). The percentages of differentiated type-A spermatogonia were not significantly increased compared with synthetic medium alone (NS, p > 0.05), but were only 5 to 7% (p < 0.001) of that of serum-containing medium. By contrast, normal transformation from gonocytes to type-A spermatogonia occurred in newborn mouse testes (n = 10) cultured with serum-free medium containing exogenous MIS. The percentage of differentiated type-A spermatogonia was approximately 77% (NS, p > 0.05) of those seen in serum-containing medium. These findings demonstrate that the transformation of gonocytes to type-A spermatogonia is regulated by MIS, rather than hCG. As early germ cell transformation is deficient in boys with cryptorchidism, the role of hCG in the treatment of infertility associated with undescended testes should be reevaluated.

Müllerian-inhibiting substance function during mammalian sexual development

To investigate the role of Müllerian-inhibiting substance (MIS) in mammalian sexual development, we generated MIS-deficient mice. Although MIS-deficient males had testes that were fully descended and produced functional sperm, they also developed female reproductive organs, which interfered with sperm transfer into females, rendering most of these males infertile. Their testes had Leydig cell hyperplasia and, in one instance, neoplasia. The actions of the two primary hormones of male sexual differentiation were genetically eliminated using the testicular feminization (Tfm) mutation in combination with the MIS mutant allele. XY Tfm/MIS double mutants developed as females, with a uterus, coiled oviducts, and no male reproductive organs except undescended dysfunctional testes. These results suggest that eliminating the presumptive female reproductive tract in male fetuses facilitates fertility and that in testes MIS is a negative regulator of Leydig cell proliferation. Eliminating the presumptive male reproductive tract is necessary for proper oviductal morphogenesis during female mouse development.

Germ cell development in neonatal mouse testes in vitro requires müllerian inhibiting substance

To study the effect of müllerian inhibiting substance on testicular germ cell development, especially on gonocytes, whole testes (156) from newborn mice were cultured for 1 to 7 days in vitro. The synthetic medium contained either 10% fetal calf serum, which itself contains endogenous müllerian inhibiting substance, or transferrin, insulin and retinoic acid. Human recombinant müllerian inhibiting substance, rabbit antiserum against müllerian inhibiting substance and/or normal rabbit serum was added to some cultures. The cultured testes were fixed in Stieve's fixative and stained with hematoxylin and eosin, and the numbers and types of germ cells per tubule were counted under a light microscope. Preliminary studies showed that germ cell development in newborn mouse testes was similar in vitro to that observed in vivo, except for delay in vitro. Normal germ cell maturation from gonocytes to primary spermatocytes occurred in testes cultured with 10% fetal calf serum only (i), 10% fetal calf serum plus müllerian inhibiting substance plus anti-müllerian inhibiting substance antibody (ii), 10% fetal calf serum plus normal rabbit serum (iii) and transferrin, insulin and retinoic acid plus müllerian inhibiting substance (iv). Maturation from gonocytes to A-type spermatogonia was arrested in testes cultured with 10% fetal calf serum plus anti-müllerian inhibiting substance antibody (p < 0.01), transferrin, insulin and retinoic acid alone (p < 0.001) and transferrin, insulin and retinoic acid plus müllerian inhibiting substance plus anti-müllerian inhibiting substance antibody (p < 0.001). The results are consistent with the hypothesis that müllerian inhibiting substance may be involved in postnatal gonocyte development and suggest that it may be useful to treat infertility associated with undescended testes.

Müllerian inhibiting substance: new perspectives and future directions

MIS, as a differentiate and antiproliferative agent, is precisely regulated, for example, at the transcriptional level by such transacting factors as SRY, and posttranslationally by testosterone. Processing of MIS most likely requires an as yet unknown in vivo protease which probably serves to control cleavage of MIS and hence its activation at specific sites wherein a localized program of cell death is initiated via a receptor mediated event. Progress has been made in understanding the molecular domains of MIS; current efforts are focused on characterizing the wild type MIS receptor as well as cloning and expressing the MIS receptor. We need now to understand how to target and efficiently activate MIS at its projected site of action. We must focus, after structural analysis of its receptor, on elucidating the MIS initiated intracellular signals which result in localized cell inhibition. Understanding of these mechanisms will permit design of antitumor agents and therapeutic strategies. Similarly, understanding regulation of MIS expression may lead to therapeutic induction of expression in those states where depressed expression is associated with tumorigenesis, sexual ambiguity, or infertility.

Persistent müllerian duct syndrome with transverse testicular ectopia and spermatogenesis

Normal male sexual differentiation is dependent on at least 2 factors: 1) testosterone and 2) müllerian inhibiting factor. The absence of müllerian inhibiting factor is responsible for a rare form of male pseudohermaphroditism, the persistent müllerian duct syndrome or hernia uteri inguinale. Patients with this syndrome present with persistent müllerian structures and the syndrome may be associated with transverse testicular ectopia. Additionally, most patients have azoospermia. We report a case of persistent müllerian duct syndrome with transverse testicular ectopia in which sperm are documented in the ejaculate.

Mapping anti-müllerian hormone (Amh) and related sequences in the mouse: identification of a new region of homology between MMU10 and HSA19p

A panel of 78 backcross progeny, BALB/cJ x (BALB/cJ x CAST/Ei)F1, was used to map the gene encoding anti-Müllerian hormone (Amh), also called Müllerian inhibiting substance, to mouse Chromosome 10 (MMU10). This analysis identified a new region of linkage homology between human Chromosome 19p (HSA 19p) and MMU10 and localized an apparent recombinational hot spot in (C57BL/6J x Mus spretus)F1 females [compared with (BALB/cJ x CAST/Ei)F1 males] to the interval between phenylalanine hydroxylase (Pah) and mast cell growth factor (Mgf). In addition, eight unlinked polymorphic sequences, provisionally designated Amh-related sequences (Amh-rs1 through Amh-rs8), were identified by Southern blot analysis using Amh probes. Amh-rs1, -rs2, -rs4, and -rs7 were mapped to MMU1, 13, 12, and 15, respectively, by recombinant inbred (RI) strain and intraspecific backcross analyses. The NXSM RI strain distribution patterns for the four unmapped loci are also presented.

Serum levels of Mullerian inhibiting substance in boys with cryptorchidism

Serum levels of Mullerian inhibiting substance (MIS) were measured in boys with cryptorchidism (n = 104) and paired, age-matched controls (n = 104) using an enzyme immunoassay. Control MIS levels were high during the first year of life with a peak level at 4 to 12 months, subsequently diminishing with age. MIS levels in patients with undescended testes also declined with age, although a surge was not found in the first year. Mean MIS concentration of cryptorchid boys was significantly lower than controls (P less than .001). There was a significant reduction of the mean MIS level in children with bilateral cryptorchidism compared with those with unilateral undescended testis (P less than .05). These differences might support the hypothesis that MIS initiates transabdominal testicular descent. However, because most undescended testes are probably the result of anatomical or functional abnormalities during transinguinal testicular descent, differences in MIS levels more likely result from secondary testicular degeneration. In the future, MIS immunoassay should play an important role in the investigation of gonadal function in boys with various genital disorders, including cryptorchidism.

Persistent müllerian duct syndrome

Persistent müllerian syndrome is rare. A case of phenotypically normal male with persistent müllerian structures that consisted of a bicornuate uterus, fallopian tubes, and upper third of the vagina is reported. These unusual structures were found in association with bilateral cryptorchidism and a right inguinal hernia, and were diagnosed while repairing the hernia in the neonatal period. The uterus and fallopian tubes were removed via laparotomy when the child was eighteen months old; at the same time a bilateral orchiopexy was performed. To avoid damage to the vas deferens, which lay in closely to the müllerian structures and could not be separated from the vaginal wall, a small segment of the upper third of the vagina was retained. The testicles, although normal on pathologic examination, have shown poor response to hormonal stimulation with human chorionic gonadotropin. Long-term follow-up for these patients is necessary because they have an increased risk of testicular tumors developing.

Unilateral biorchism associated with contralateral rudimentary uterus

A healthy 5-year-old boy presented with two palpable masses in the right hemiscrotum. An examination also showed a palpable mass in the left groin. During surgery, he was found to have right-sided biorchism and a left groin nodule attached to the left vas deferens and spermatic cord. The nodule was excised and histologic examination showed the presence of persistent Mullerian structures. A chromosome analysis showed the normal male karyotype. Both conditions have been previously reported, but this is the first report of both conditions occurring in the same patient.

Recombinant human müllerian inhibiting substance inhibits epidermal growth factor receptor tyrosine kinase

Autophosphorylation of the epidermal growth factor (EGF) receptor in A-431 cells and plasma membrane fractions was inhibited by partially purified recombinant human Müllerian Inhibiting Substance (MIS). Immunoprecipitation of the EFG receptor using anti-EGF receptor or anti-phosphotyrosine antibodies, and phosphoamino acid analysis of this receptor, demonstrated that MIS specifically inhibited EGF-induced tyrosine phosphorylation. Inhibition of EGF receptor autophosphorylation by MIS in membrane preparations was not affected by increasing concentrations of EGF, manganese or [gamma-(32)P] ATP. Thus, it is unlikely that MIS competes for EGF binding sites or sequesters substrate. Immunoabsorption of MIS with anti-human MIS antibody blocked the MIS inhibition of EGF receptor autophosphorylation, indicating that the inhibition was due to MIS. Our data suggest that MIS regulates the activity of the EGF receptor tyrosine kinase in A-431 cells.

The Hutson hypothesis. A clinical study

The hypothesis that testicular descent may be governed by Müllerian inhibiting substance (MIS) was investigated by observing the position of the testes in 13 children with XY karyotype and persistent Müllerian duct syndrome (PMDS). It was found that there was a direct relationship between failure of testicular descent and the degree of development of the Müllerian system. Where the Müllerian system was complete, the testes were in an ovarian position but where only the vagina was present, the testes were sometimes found in the inguinal region. To discover whether excessive androgen activity in females might produce ovarian descent, the position of the ovaries in 15 children with severe adrenogenital syndrome was observed. Despite complete genital masculinisation in three children and almost complete in six, all but one ovary was in the normal position: that ovary had descended in an inguinal hernia sac. These findings suggest that MIS rather than androgens may be responsible for the first or abdominal phase of testicular descent. Even excessive androgen activity failed to cause ovarian descent.

Müllerian inhibiting substance blocks autophosphorylation of the EGF receptor by inhibiting tyrosine kinase

The fetal regressor Müllerian inhibiting substance (MIS), in concentrations as low as picomolar, inhibited the growth of A-431 cells and the autophosphorylation of its epidermal growth factor (EGF) receptor. The inhibition of membrane phosphorylation was due neither to the reduction of the total number of EGF receptor binding sites, nor to stimulation of intrinsic phosphates, but rather to inhibition of tyrosine kinase activity. MIS control of EGF receptor autophosphorylation by tyrosine kinase may be one mechanism by which Müllerian duct regression in the embryo and the inhibition of A-431 proliferation is initiated. In addition, MIS as an inhibitor of phosphorylation may furnish a tool to probe the role of membrane phosphorylation in growth control.

Müllerian inhibiting substance as oocyte meiosis inhibitor

Müllerian inhibiting substance (MIS) inhibited the resumption of meiosis in both denuded and cumulus cell-enclosed rat oocytes in vitro. Spontaneous germinal vesicle breakdown was prevented in both types of oocytes treated by a purified MIS preparation at protein concentrations of 15 micrograms to 150 pg/ml. The inhibiting effect of MIS on the resumption of meiosis was dose dependent, reversible and cyclic AMP independent. Neither follicular-stimulating hormone, luteinizing hormone, progesterone, estradiol, nor testosterone acted significantly to influence MIS-mediated inhibition of rat oocyte maturation. In contrast, MIS had no influence on meiosis in the mouse, where other protein has been reported to inhibit the cumulus cell-enclosed oocyte in a cyclic AMP-dependent fashion. Thus MIS may be yet another inhibitor of oocyte meiosis, acting in the rat by a mechanism different from those inhibitors known, in the mouse ovary, to exert their effect in a cyclic AMP-dependent manner.

Persistence of müllerian ducts in male rabbits passively immunized against bovine anti-müllerian hormone during fetal life

A female rabbit was immunized against purified bovine AMH and mated. Booster injections were given at Day 8 of pregnancy to ensure a high titer of anti-AMH antibodies at the time the rabbit fetal testis begins to produce AMH. In three consecutive litters, the immunized female produced a total of 12 males, 9 of which had persistent Müllerian duct derivatives. No other significant abnormalities were detected in these animals, which were compared to the offspring of a control saline-injected female. In particular, testicular morphology was normal in most animals, and serum FSH levels did not differ from controls. This experimental model lends no support to the hypothesis that AMH controls extra-Müllerian events of male sex differentiation, nor that of the existence of a regulatory mechanism for synthesis of AMH by Sertoli cells, but it does not definitely exclude these possibilities, inasmuch as our tentative conclusions are based upon study of only one immunized female.

Isolation of the bovine and human genes for Müllerian inhibiting substance and expression of the human gene in animal cells

We have isolated the bovine and human genes for Müllerian inhibiting substance (MIS), a testicular glycoprotein that causes regression of the Müllerian duct during development of the male embryo. The mRNA sequence of bovine MIS, determined from an analysis of cDNA and genomic clones, codes for a protein of 575 amino acids containing a 24 amino acid leader peptide. The human gene has five exons that code for a protein of 560 amino acids. A comparison of the bovine and human MIS proteins reveals a highly conserved C-terminal domain that shows marked homology with human transforming growth factor-beta and the beta chain of porcine inhibin. Animal cells transfected with the human gene secrete biologically active MIS, which causes regression of the rat Müllerian duct in vitro.

Mullerian inhibiting substance: a fetal hormone with surgical implications

Mullerian Inhibiting Substance (MIS) is secreted from the fetal (and postnatal) testis and is known to cause regression of the Mullerian ducts, the anlage of the fallopian tubes, uterus and upper vagina. It is a large glycoprotein hormone, the action of which appears to be modulated by sex steroids: mainly testosterone in mammals and oestrogen in birds. Recent evidence has raised the possibility that its action may be to diminish cell surface phosphorylation and thereby change the direction of differentiation of the Mullerian duct towards regression. Other suspected functions for MIS include control of testicular descent and inhibition of malignant tumours of the female genital tract.

Persistent Müllerian duct syndrome. Review and report of 3 cases

Three cases of persistent Müllerian duct syndrome are reported. All were phenotypically and karyotypically male but with persistent duct remnants. Problems encountered in management and surgery are discussed.

Timing and irreversibility of Müllerian duct inhibition in the embryonic reproductive tract of the human male

A study was undertaken to determine (1) the effects of endogenous Müllerian inhibiting substance (MIS) on the developing human fetal genital tract; (2) the time in fetal life when MIS is first capable of inhibiting the growth of the embryonic Müllerian ducts; and (3) the reversibility of the effects of MIS on the developing male Müllerian ducts. Human fetal reproductive tracts were transplanted and grown for sustained periods in vivo in athymic nude mice. The genital tracts from 12 male human fetuses, ages 51 to 68 days postovulation, were grafted without their associated gonads into castrated murine hosts and grown for 30 to 70 days. Controls consisted of genital tracts from 8 female human fetuses, ages day 53 to 70 that were grown under identical conditions. Male specimens grew to approximately one-half the size of female specimens and disclosed varying degrees of inhibition of the Müllerian duct system from absence of the Müllerian ducts in older specimens (after Day 63) to poorly segregated segments of stroma as the mildest defect (less than Day 61). It is concluded that (1) MIS secretion by the embryonic testes probably begins before Day 51 of gestation; (2) the effects of MIS are progressive during the so-called critical window; (3) the effects of MIS are permanent; and (4) the mesenchyme is an important target of MIS.

Persistence of Müllerian ducts in male pseudohermaphroditism, and its relationship to cryptorchidism

Twenty-two cases of male pseudohermaphroditism with persistence of Müllerian duct derivatives were reviewed. In 12 cases of mixed gonadal dysgenesis and five cases of dysgenetic male pseudohermaphroditism, testosterone-dependent steps of sex differentiation were also impaired, and testicular dysgenesis was prominent, even in the younger age group. The capacity of testes to inhibit the ipsilateral Müllerian duct was correlated with testicular descent: it is suggested that testicular dysgenesis explains both the functional and topographical testicular abnormalities observed in these male pseudohermaphrodites. Five other patients were cryptorchid but externally normally virilised, persistence of Müllerian derivatives representing their only abnormality of sex differentiation. Testicular structure was usually normal or showed changes attributable to long-standing cryptorchidism. It is suggested that in these patients, persistence of Müllerian derivatives is due to an inborn error of metabolism, affecting the binding of anti-Müllerian hormone to its receptor and that failure of testicular descent is caused by mechanical restraint by the abdominal Müllerian organs.

Dysgenesis of testicular and streak gonads in the syndrome of mixed gonadal dysgenesis: perspective derived from a clinicopathologic analysis of twenty-one cases

The clinical and pathologic aspects of 21 cases of mixed gonadal dysgenesis (MGD) were studied. The gonads in 15 patients consisted of a macroscopic testis and a streak gonad; six patients had variants, including two with bilateral testes and four with bilateral streak gonads or tumors. Functionally, the gonads were incompetent. Testes 1) failed to completely inhibit müllerian development, 2) failed to support full differentiation of mesonephric duct structures, 3) failed to adequately masculinize development of the external genitalia, or 4) often failed to mediate their own descent, resulting in asymmetry of the internal and external genitalia. None of the streak gonads mediated normal female adolescent development or fertility. Microscopic examination revealed that every gonad, regardless of its gross appearance, was morphologically abnormal. Although gonads with seminiferous tubules usually developed to a moderately advanced state, macroscopically resembling testes, the hilar zone remained architecturally disorganized; the cortex invariably lacked more than a rudimentary tunica albuginea or exhibited partial ovarian differentiation, sometimes even with a rare primordial follicle. Over time, the seminiferous tubules atrophied and hyalinized. Gonads that grossly resembled streak gonads were observed microscopically to be composed of a stroma resembling that of normal ovarian cortex. In patients more than several years of age, the entire complement of germ cells in streak gonads disappeared. It is suggested that patients with MGD be raised as females. Early removal of gonads will prevent the development of gonadoblastoma and dysgerminoma. If the uterus is retained and the patient is subsequently given exogenous estrogen, care should be taken to detect early any signs of the development of endometrial carcinoma or its precursor, to which these patients may be prone.

Normal development of the human female reproductive tract and alterations resulting from experimental exposure to diethylstilbestrol

An in vivo model is described for the study of human uterovaginal development in the presence and absence of the teratogenic drug diethylstilbestrol (DES). Intact reproductive tracts from fragments of 29 human embryos and fetuses 5.0 to 17.7 weeks of age obtained after dilatation and curettage were grown for four weeks in vivo in athymic (nude) mice that were either untreated (control) or implanted subcutaneously with a DES pellet. Control specimens grown in vivo continued their anticipated morphogenesis for equivalent in-utero ages; the normal processes observed included fusion of the paired embryonic müllerian ducts into a single uterovaginal canal, stratification of endometrial and tubal mesenchyma into inner (presumptive endometrial stroma) and outer (presumptive myometrium) layers; plication of tubal and endometrial mucosa; uterine gland formation; and stratification (transformation) of the simple columnar epithelium of the vagina and cervix into a stratified squamous plate. Specimens exposed in vivo to DES exhibited anomalies, many of which mimicked those observed clinically in young women exposed prenatally to DES. Glandular epithelium (adenosis) was found in the vagina. The upper genital tract was malformed; its growth was stunted, and the inner and outer stromal layers of the uterine corpus and fallopian tubes failed to segregate. The authors conclude that the in vivo model that they describe, with its built-in controls, provides a valid approach for examining the dynamics of morphogenesis and cytodifferentiation in developing human genital tracts under experimentally regulated conditions.

The diagnosis and management of intersex

The patient whose genitalia are ambiguous or are inappropriate for the assigned sex presents the physician with a set of problems requiring a thorough grasp of sexual differentiation, development and function. Although several reviews have covered various aspects of these matters, these texts do not cover recent advances in understanding normal and abnormal sexual development nor do they provide an integrated guide to the management of intersex cases. Our objectives are to show the clinical relevance of recent advances in understanding the determinants of normal and abnormal sexual differentiation, to indicate the improved diagnostic procedures now available and to provide specific guidelines for optimal case management in the light of current medical knowledge and psychological and ethical understanding.

Abnormalities of the vas deferens and epididymis in cryptorchid boys with congenital rubella

Cryptorchidism was present in 12% of 316 boys with congenital rubella (CR) followed by The Roosevelt Hospital Rubella Project. Eight of these patients, age 4 through 16 yr, had a recent orchiopexy, 4 on the left, 2 on the right, and 2 bilaterally. The vasoepididymal system was absent or apparently obstructed in 60% of the 10 sides. The epididymis was abnormal in 6 instances and the vas deferens in 5. Sixty-one boys of the entire series had an intravenous pyelogram (IVP) that was significantly abnormal in 18%. The 8 patients described all had a normal IVP except for 2 who had a malrotated kidney on the involved side. In 5 of the 8, a known maternal rubella infection has occurred during the first 8 wk of gestation. As the rubella virus is known to interfere with cellular growth and tissue differentiation in early pregnancy, it apparently altered the developing testis and mesonephric duct system. Similar vasoepididymal abnormalities have been described previously in patients with uncomplicated cryptorchidism, inguinal hernia, kidney defects, cystic fibrosis and male sterility. Their presence should alert the clinician to perform an IVP and also consider a diagnosis of congenital rubella.

The secretion of Mullerian inhibiting substance by cultured isolated Sertoli cells of the neonatal calf

Sertoli cells have been insolated from the newborn calf testis using a combination of mechanical and enzymatic disruption. Testicular fragments, previously chopped into 1-mm pieces, are digested in an enzyme mixture consisting of hyaluronidase, collagenase, trypsin and DNAse, followed by a second digestion in trypsin and DNAse. Isolation of the resulting cellular fractions by sedimentation with unit gravity produces an aliquot of Sertoli cells which is over 95% pure when examined by light and electron microscopy. Cultures of these cells grow rapidly and produce Mullerian Inhibiting Substance as evidenced by their ability to cause the involution of the Mullerian duct of the female fetal rat when co-cultured in an organ-culture assay system.

Mixed gonadal dysgenesis, pathogensis, and management

Fourteen patients with Mixed Gonadal Dysgenesis who presented as infants or children are discussed. Gonadal asymmetry, and/or sex chromosomal mosaicism, as well as retained Mullerian Ducts characterize the anomaly. The dysgenetic testis may occur as the result of a cascade of development mishaps stemming from abnormalities of H-Y antigen expression or function that lead to abnormal differentiation of the indifferent urogenital ridge and, in turn, to aberrant production of Mullerian inhibiting Substance and testosterone. The latter two cause retention of Mullerian ducts and incomplete masculinization of the external genitalia. Absence of a second X chromosome may lead to the formation of a streak ovary, in which the dysgenetic testis may invoke formation of hilar and medullary cords. Neoplastic transformation, so characteristic of this group of patients, may result from unprotected germ cells and abnormally high and prolonged gonadotropin stimulation. Gonadoblastoma and seminoma-dysgerminomas are the tumors found in the gonads with the risk exceeding 50% as the third decade is approached. Laterality of the gonads in this anomaly remains an enigma. The gonads should be removed at birth if possible and the external genitalia repaired soon thereafter. These patients should be raised as females. The risk of neoplastic transformations must be considered at all stages of management.

Management of neonates and children with male pseudohermaphroditism

Twenty-five patients with male pseudohermaphroditism were treated. Causes included (1) inadequate testosterone production, (2) incomplete conversion of testosterone to dihydrotestosterone, and (3) insufficient androgen-binding protein at the target cell. These various problems can be defined accurately today. These infants should be studied early to define which gender role is more appropriate. Change in gender assignment later can be disastrous. An individual raised in the female role, but with incomplete internal structures, can cope with life better than one raised in the male role but lacking a satisfactory phallus. In general, we believe most male pseudohermaphrodites should be raised as females, performing appropriate alterations at an early age.