A sensitive radioimmunoassay for bovine anti-Müllerian hormone, allowing its detection in male and freemartin fetal serum

Characterization of anti-Müllerian hormone in a case of bovine male pseudohermaphroditism

The current report aimed to characterize plasma anti-Müllerian hormone (AMH) in bovine male pseudohermaphroditism. The blood AMH concentration in a Japanese Black male pseudohermaphrodite calf was compared with pre- and post-pubertal male and female calves and castrated calves. The concentration in the case was higher than in post-pubertal males, castrated males, and pre- and post-pubertal female calves (p < .05), but similar to that in pre-pubertal male calves. After extraction of the testes, the concentration in the case dropped to a certain extent. The extracted testes expressed AMH, as detected by immunohistochemistry. This study is the first to show the characterization of AMH in a male pseudohermaphrodite calf. AMH levels in peripheral blood might be useful to diagnose male pseudohermaphroditism in cattle.

The role of AMH in the pathophysiology of polycystic ovarian syndrome

Polycystic ovarian syndrome (PCOS) affects 5 - 10% of reproductive age women, but its pathogenesis is still poorly understood. The aim of this review is to collate evidence and summarize our current knowledge of the role of anti-Müllerian hormone (AMH) in PCOS pathogenesis. AMH is increased and correlated with the various reproductive and metabolic/endocrine alterations in PCOS. AMH plays an inhibitory role in follicular development and recruitment, contributing to follicular arrest. AMH inhibitory action on FSH-induced aromatase production likely contributes to hyperandrogenism in PCOS, which further enhances insulin resistance in these women. Elevated serum AMH concentrations are predictive of poor response to various treatments of PCOS including weight loss, ovulation induction and laparoscopic ovarian drilling, while improvement in various clinical parameters following treatment is associated with serum AMH decline, further supporting an important role for AMH in the pathophysiology of this syndrome. This review emphasizes the need for understanding the exact mechanism of action of AMH in the pathophysiology of PCOS. This may lead to the development of new treatment modalities targeting AMH to treat PCOS, as well as help clinicians in prognostication and better tailoring existing treatments for this disease.

Anti-Müllerian hormone is a gonadal cytokine with two circulating forms and cryptic actions

Anti-Müllerian hormone (AMH) is a multi-faceted gonadal cytokine. It is present in all vertebrates with its original function in phylogeny being as a regulator of germ cells in both sexes, and as a prime inducer of the male phenotype. Its ancient functions appear to be broadly conserved in mammals, but with this being obscured by its overt role in triggering the regression of the Müllerian ducts in male embryos. Sertoli and ovarian follicular cells primarily release AMH as a prohormone (proAMH), which forms a stable complex (AMHN,C) after cleavage by subtilisin/kexin-type proprotein convertases or serine proteinases. Circulating AMH is a mixture of proAMH and AMHN,C, suggesting that proAMH is activated within the gonads and putatively by its endocrine target-cells. The gonadal expression of the cleavage enzymes is subject to complex regulation, and the preliminary data suggest that this influences the relative proportions of proAMH and AMHN,C in the circulation. AMH shares an intracellular pathway with the bone morphogenetic protein (BMP) and growth differentiation factor (GDF) ligands. AMH is male specific during the initial stage of development, and theoretically should produce male biases throughout the body by adding a male-specific amplification of BMP/GDF signalling. Consistent with this, some of the male biases in neuron number and the non-sexual behaviours of mice are dependent on AMH. After puberty, circulating levels of AMH are similar in men and women. Putatively, the function of AMH in adulthood maybe to add a gonadal influence to BMP/GDF-regulated homeostasis.

The freemartin syndrome: an update

The freemartin condition represents the most frequent form of intersexuality found in cattle, and occasionally other species. This review considers the current state of knowledge of freemartin biology, incidence, experimental models, diagnosis, uses for freemartins in cattle herds, occurrence in non-bovine species, effects on the male, and highlights potential new research areas. Freemartins arise when vascular connections form between the placentae of developing heterosexual twin foeti, XX/XY chimerism develops, and ultimately there is masculinisation of the female tubular reproductive tract to varying degrees. With twinning rates in Holstein cows increasing, there will be greater economic importance to establish early diagnosis of the freemartin and the detection of the less common single born freemartin. New diagnostic methods based on the detection of Y-chromosome DNA segments by polymerase chain reaction (PCR) show improved assay sensitivity and efficiency over karyotyping and clinical examination. The implications for the chimeric male animal born co-twin to the freemartin are contentious as to whether fertility is affected; if germ cell chimerism does indeed occur; and, if there are any real effects on the sex ratio of offspring produced. In beef cattle, the freemartin carcass has similar characteristics to normal herdmates. Hormonal treatment of freemartins for use as oestrous detectors has been used to obtain salvage value. The biology of freemartin sheep has recently been studied in detail, and the condition may be increasing in prevalence with the introduction of high fecundity genes into flocks. Potential new research areas are discussed, such as detection of foetal DNA in maternal circulation for prenatal diagnosis and investigation of the anti-tumour properties of Mullerian inhibiting substance (MIS). The freemartin syndrome will always be a limiting factor in cattle and to a lesser extent in sheep production systems that have the goal to produce multiple reproductively normal female offspring from a single dam without using sex predetermination.

Age dependent changes in plasma anti-Müllerian hormone concentrations in the bovine male, female, and freemartin from birth to puberty: relationship between testosterone production and influence on sex differentiation

To understand the behaviour of the gonads, in terms of hormonal secretion, in a model of intersexual development naturally occurring in mammals, we determined plasma concentrations of testosterone, progesterone, and anti-Müllerian hormone (AMH) in bovine freemartins, and compared them to normal levels measured in males and females from birth to puberty. We found that newborn males and freemartins have very high concentrations of AMH (over 700ng/ml). Conversely, plasma AMH concentration is always below 120ng/ml in females. While values remain stable in males for the first five months of life, they sharply decrease in the freemartins within the first fortnight, and reach female levels, which demonstrates that AMH is essentially originated in the male twin. In young bulls the trend of plasma testosterone concentrations is opposite to that of the AMH. The rise in testosterone production at puberty corresponds to a sharp decline in AMH concentrations. Bovine plasma concentrations of AMH are surprisingly higher than those measured in other mammals, including man and mouse. The results obtained are discussed in reference to comparative aspects of endocrine functions.

Testicular differentiation in mammals under normal and experimental conditions

Gonadal differentiation begins with the establishment of a sexually undifferentiated gonad, in which gonadal cords are formed by condensation of somatic cells and deposition of basal laminar components around the cluster of epithelial-like cells. The first event of sexual differentiation is the invasion of mesenchymal and endothelial cells into the genital ridge in the XY gonad. As a consequence of this event, the gonadal cords become conspicuous, recognized as seminiferous cords (or testis cords). Cytological differentiation of Sertoli cells follows these stromal changes. In the XX gonad, by contrast, the invasion of the mesenchyme is absent and gonadal cords remain associated with the surface epithelium. In the B6.YDOM XY ovotestis, seminiferous cords and ovarian gonadal cords are often enveloped by common basal laminae, confirming that both structures share the embryonic origin. It has been recently reported that seminiferous-like cords are formed after loss of oocytes in the rat XX ovary cultured in the presence of Müllerian inhibiting substance or after long-term culture in the basic medium alone. These results are comparable with our observation on the persistent gonadal cords in the ovary of busulphan-treated rats or W/WV mutant mice, in which oogonia are absent or scarce. Ultrastructural evidence for Sertoli cell differentiation from XX cells has been presented, so far, only in the fetal mouse ovary that has been grafted beneath the kidney capsule of adult male mice. Possible mechanism of gonadal sex determination is discussed based on these morphological studies.

A monoclonal antibody against human testicular anti-müllerian hormone

Using immunochromatography on a polyclonal antibody, testicular anti-Müllerian hormone (AMH) was purified from homogenates of human fetal testicular tissue and used as an antigen for hybridoma production. Two IgM clones were obtained. Both recognized AMH on biopsies of human testicular tissue and one blocked its anti-Müllerian activity. This monoclonal antibody (MAb) exhibited a relatively high affinity for AMH, and was studied further. It is interspecific, recognizing AMH in other mammalian species. The study of this MAb in relation to an IgM MAb raised against bovine AMH (bAMH) indicates that both MAbs recognize different but related epitopes on bAMH.

Quantification of müllerian inhibiting substance in developing chick gonads by a competitive enzyme-linked immunosorbent assay

An immunoblotting method was used to purify a Müllerian-inhibiting substance (MIS)-specific antiserum. The serum was used to quantify the content of MIS in developing chick gonads by competitive enzyme-linked immunosorbent assay. From embryonic stages to the eleventh week after hatching, male chicken testes have a high content of MIS in the following two stages: (1) from the sixth to the eighth day and from the fourteenth to the twentieth day of incubation, and (2) from the second to the eighth week after hatching. The high content of MIS in the early embryonic stage is closely correlated with the natural pattern of Müllerian duct regression observed in the male embryo. From the sixth to the twelfth day of incubation, the female right ovary contains a higher content of MIS than that of the left ovary. Up to the fourteenth day of incubation, the content of MIS in the left ovary reaches maximum levels and then declines. The combination of MIS from right and left ovaries was found to be highest in the ninth to the fourteenth day of incubation, when the regression of the right Müllerian duct reached its highest peak. However, the question of the inability of MIS to cause regression of the female left Müllerian duct and the caudal part of the right duct is raised and discussed. The hypothesis that prenatal estrogenic hormone (diethylstilbestrol) protects the Müllerian duct has been reevaluated. It was found that estrogen does not reduce the MIS content in prenatally treated gonads.

Secretion of the anti-müllerian hormone by the gonads of experimentally sex reversed female chick embryos

The gonads of genetically female chick embryos experimentally transformed into testes under the influence of a embryonic testis graft are able to induce in vivo the regression of Müllerian ducts when they are grafted to female embryonic hosts. On the other hand female gonads only transformed into ovotestes are ineffective on the host MDs, as in the case for female gonads. These results show that totally sex reversed gonads have the same properties as a normal testis. In particular they produce the anti-Müllerian hormone, whereas partially reversed gonads do not or only do at a very low level.

Cloning and expression of cDNA for anti-müllerian hormone

Messenger RNA, prepared from fetal bovine testicular tissue, was used to construct a cDNA library in lambda gt11 phage. The library was screened with an antibody probe directed against bovine anti-Müllerian hormone and three positive clones were isolated. Cross-hybridizing cDNA inserts carried by clones 4 and 5 (1.2 and 0.08 kilobases long, respectively) code for a fragment of authentic anti-Müllerian hormone, as shown by the ability of the anti-epitope antibodies eluted from fusion protein 4 to bind strongly to anti-Müllerian hormone on immunoblots and by the capacity of anti-epitope antibodies 4 and 5 to precipitate radioiodinated bovine anti-Müllerian hormone. A probe prepared from insert 4 hybridizes with an mRNA present only in tissues that are known producers of anti-Müllerian hormone, such as the fetal testis and adult ovarian follicles. The amount of specific mRNA in tissues of males and females is related to the rate of their anti-Müllerian hormone production. The 2.1-kilobase size of this mRNA species is large enough to code for the Mr 62,000 anti-Müllerian hormone polypeptide chain. Insert 4 also hybridizes with an mRNA of similar size in human and rat fetal testicular tissue. The third isolated clone, clone 8, which does not cross-hybridize with the others, carries a cDNA insert coding for a ubiquitous protein, smaller than anti-Müllerian hormone, with which it apparently shares an epitope.

Biochemical analysis of bovine testicular anti-Müllerian hormone

Direct biochemical analysis has been applied to bovine testicular anti-Müllerian hormone (AMH), purified from incubation medium of bovine fetal testes by immunochromatography on a monoclonal antibody. The hormone contains a high proportion of hydrophobic amino acids and 13.5% carbohydrate. The oligosaccharide composition suggests that both N- and O-glycosidically linked chains are present. The molecular extinction coefficient is 3.27 +/- 0.06. One RIA unit, defined as the amount of hormone released by 1 g fetal bovine testicular tissue incubated during 4 h, corresponds to 3.06 +/- 0.17 microgram protein.

Secretion of anti-Müllerian hormone by immature bovine Sertoli cells in primary culture, studied by a competition-type radioimmunoassay: lack of modulation by either FSH or testosterone

Secretion of anti-Müllerian hormone (AMH) by immature bovine Sertoli cells in primary culture was studied through a competition-type RIA employing a polyclonal antibody and 125I-labelled purified AMH. This RIA is approximately 10 times more sensitive than the solid-phase two-site monoclonal antibody-based RIA described previously. Biosynthesis and secretion of AMH by cultured Sertoli cells require approximately 48 h, are not influenced by FSH or testosterone and steadily decrease over a one-week period of culture. Cyclic AMP response to FSH stimulation is normal in cultured cells. Whether the factors responsible for the extinction of AMH production in vitro are in any way related to those operating during normal maturation, which lead to repression of AMH biosynthesis in adult Sertoli cells, is not known at the present time and deserves further study.

Purification of testicular anti-Müllerian hormone allowing direct visualization of the pure glycoprotein and determination of yield and purification factor

An improved method is described for the purification of anti-Müllerian hormone from incubation medium of bovine fetal testes, using RIA to optimize the yield at different steps. Proteins present in incubation medium are precipitated by ammonium sulphate at 30-45% saturation and subjected to ion-exchange chromatography on DEAE-Sepharose. The bulk of the hormone is eluted from the ion-exchanger by a 0.12 M concentration of NaCl. Purification is achieved by immunochromatography on a monoclonal antibody: usually, addition of extraneous protein to the eluting buffer is required, but can be dispensed with if a second, cumulative, immunochromatography is performed by pooling the eluates from the first procedure. AMH obtained by this procedure has been studied using Coomassie blue and immunoblotting, and compared with fucose-labelled AMH, which is recognized by the same monoclonal antibodies as the carrier of the anti-Müllerian biological activity. In the absence of reducing conditions, several multimers, from 145 000 to 235 000 in molecular weight, are present. Reduction of disulphide bond linkages results in the disappearance of the multimeric forms, and the appearance of a 72 000 monomer. Equivalence between RIA and weight units has been established in one experiment: one AMH unit corresponds to 15 micrograms of protein. Pure AMH isolated by this procedure is highly bioactive at a concentration of 200 mU/ml.

Mullerian inhibiting substance fractionation by dye affinity chromatography

Mullerian inhibiting substance (MIS), a large glycoprotein secreted by the fetal and neonatal testis, is responsible for regression of the Mullerian ducts in the male embryo. This fetal growth regulator has been purified more than 2000-fold from crude testicular incubation medium following fractionation on a triazinyl dye affinity support. A high yield of 60% recovered activity was achieved in the absence of exogenous carrier protein by stabilizing MIS with 2-mercaptoethanol, EDTA, and Nonidet-P40 and eliminating losses in the handling and concentration of MIS fractions. Although affinity elution with nucleotides has proved successful in other systems, MIS could not be eluted with ATP, GTP, or AMP, with or without divalent metal ions. Nucleotide elution, however, does remove contaminating proteins prior to MIS recovery with high ionic strength. The 2000-fold-purified MIS fraction, although not homogeneous, shows a reduction-sensitive band after SDS-gel electrophoresis that has been proposed to be the MIS dimer.