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N Josso

Publications and source records attributed to N Josso.

At least 73 records · Page 4Linked to original sources
PubMed1990

Expression of the gene for anti-Müllerian hormone.

The expression of anti-Müllerian hormone, also called Müllerian-inhibiting substance or factor, is limited to immature Sertoli and post-natal granulosa cells. To gain information on the genetic mechanisms of this tissue- and development-specific regulation, a human genomic clone containing 3.6 kilobases of 5' flanking sequences has been isolated and sequenced. Transcription initiation sites include a major site, at the same position as in the bovine gene, and 3 minor sites, accounting together for 12% of transcripts. Sequences of potential interest include an Sp1 binding site, minisatellite-like regions, and a 13-base pair palindrome, nearly identical to the oestrogen response element of the vitellogenin genes. This palindrome binds to the human oestrogen receptor in vitro and activates transcription of a hybrid gene when several copies are inserted 5' of a thymidine kinase promoter. Further studies are needed to determine whether this palindrome is implicated in a feed-back loop regulating oestrogen synthesis in granulosa cells.

Anti-Mullerian Hormone↗
PubMed1989

Anti-idiotypic antibodies to a monoclonal antibody raised against anti-müllerian hormone exhibit anti-müllerian biological activity.

Polyclonal anti-idiotypic antibodies were raised to three monoclonal antibodies to bovine anti-Müllerian hormone, and purified by affinity chromatography. All anti-idiotypes inhibited binding of labelled anti-Müllerian hormone to the monoclonal antibody against which they were directed; in addition, the anti-idiotypes directed against a non-zoospecific monoclonal antibody inhibited binding of labelled anti-Müllerian hormone to a monoclonal antibody raised against human testicular AMH, indicating that the idiotype against which these anti-idiotypes are directed recognizes a conserved epitope on the anti-Müllerian hormone molecule. These anti-idiotypes, but not those directed against other monoclonals, exhibit hormone-like activity in a bioassay for anti-Müllerian activity, and we suggest that they may act as antibodies against the anti-Müllerian hormone receptor.

Animals↗
PubMed1989

Anti-Müllerian hormone produces endocrine sex reversal of fetal ovaries.

We have previously reported that anti-Müllerian hormone (AMH), also known as Müllerian-inhibiting substance, the testicular glycoprotein involved in regression of the Müllerian ducts of the male fetus, induces the formation of seminiferous cord-like structures in fetal ovaries exposed to it in organ culture. We have now investigated the effect of bovine AMH, purified to homogeneity, on ovarian endocrine differentiation. Ovine fetal ovaries exposed to AMH release testosterone instead of estradiol, an endocrine sex reversal due to suppression of aromatase activity. AMH dramatically decreases the conversion rate of testosterone to estradiol and also decreases total aromatase activity, as measured by the tritiated water technique. AMH acts by decreasing aromatase biosynthesis rather than by blocking enzyme activity, as suggested by the relatively long period of AMH exposure required to produce an effect. In the rabbit fetal ovary, aromatase activity is AMH-responsive during the whole gestational period. The basal steroidogenic activity of rat fetal ovaries is extremely low but can be markedly increased by cAMP. AMH completely blocks the effect of cAMP. Taken together, our results suggest that AMH plays a pivotal role in both morphological and endocrine gonadal sex differentiation.

Animals↗
PubMed1988

Anti-müllerian hormone in sheep follicles.

The purpose of this work was to study anti-Müllerian hormone (AMH) secretion during ovarian development in sheep before and after birth. We used avidinbiotin immunocytochemistry and a monoclonal antibody specific for ruminant AMH. Only granulosa cells have an immunoreactivity; this immunoreactivity was influenced by animal age and by the degree of follicular development. In the fetus, no immunoreactivity was detected in somatic cells of ovigerous cords at 70 days post-coitum (p.c.) or in primordial and growing follicles at 100 and 120 days p.c. A faint reaction was only seen occasionally in a few cells belonging to preantral follicles at 120 days p.c. AMH was never detected in primordial follicles in ovaries of 144 days p.c., at birth, at 8, 97, 145 days post-natal or in adult ovaries. A faint reaction, elicited in small growing follicles, increased with follicle size to become more intense in antral follicles. Immunoreactivity was strongly positive in granulosa cells, especially in those lining the antral cavity and close to the oocyte, whereas there was little or no reactivity in peripheral cells near the basal membrane. Follicles without AMH reactivity were found at all times and their number decreased with age.

Aging↗
PubMed1988

Anti-müllerian hormone and freemartinism: inhibition of germ cell development and induction of seminiferous cord-like structures in rat fetal ovaries exposed in vitro to purified bovine AMH.

In 13 and 14-day old fetal rat ovaries maintained 3 to 10 days in organ culture, purified bovine anti-Müllerian hormone (AMH) (1.5 to 3 micrograms/ml) induced a characteristic freemartin effect. Gonadal volume and germ cell number were significantly reduced, compared to control ovaries cultured in anhormonal medium, and epithelial cells with large clear cytoplasm linked by interdigitations differentiated in the gonadal blastema. These cells resembling rat fetal Sertoli cells became polarized and formed seminiferous cord-like structures delineated by a basal membrane containing laminin and fibronectin as is the case of testicular seminiferous cords at the first step of their differentiation. These data indicate that AMH is probably the testicular factor responsible for the morphological modifications of bovine freemartin gonads and suggest that this hormone could also be involved in normal morphological differentiation of the testis. In contrast, in fetal rat ovaries, AMH did not trigger the testosterone production which occurs in freemartin gonads at an early stage of the gestation.

Animals↗
PubMed1988

Immunopurified anti-müllerian hormone does not inhibit spontaneous resumption of meiosis in vitro of rat oocytes.

The ability of immunopurified, biologically potent anti-Müllerian hormone (AMH) to inhibit the spontaneous resumption of meiosis of rat oocytes was tested in vitro. Two different batches of AMH in the range of 0.75-9.0 micrograms/protein did not suppress the spontaneous resumption of meiosis. Neither did AMH (6 micrograms/ml) induce meiotic resumption of follicle-enclosed oocytes in culture. It is concluded, therefore, that AMH has no oocyte meiosis-inhibiting activity.

Animals↗
PubMed1988

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.

Anti-Mullerian Hormone↗
PubMed1988

Disorders of gonadal differentiation and congenital adrenal hyperplasia.

Ambiguity of the external genitalia may be based on disordered steroid biosynthesis or may arise from fundamental genetic and chromosomal abnormalities that produce failure of gonadogenesis. This article first discusses congenital adrenal hyperplasia and then considers the diverse abnormalities that cause disordered gonadal differentiation.

Adrenal Hyperplasia, Congenital↗
PubMed1987

Immunocytochemical detection of anti-müllerian hormone in Sertoli cells of various mammalian species including human.

An immunocytochemical method, based on the use of a polyclonal antibody raised against purified bovine anti-Müllerian hormone (AMH), was used to detect AMH in Sertoli cell cytoplasm of various mammalian species, including human. Immunopurification of antiserum by AMH-affinity chromatography, although not mandatory, leads to better results and increased sensitivity. In human testicular tissue, AMH is detectable up to 6 years of age. In rats, AMH production is initiated at 13 days post coitum, peaks between 15 and 17 days, and is no longer detectable 1 week after birth. The reaction is strongest in Sertoli cells of calves, sheep, goats, and pigs, species characterized by a high degree of development of the rough endoplasmic reticulum. It is fainter in human, rat, rabbit, and cat Sertoli cells, in which the rough endoplasmic reticulum is not as abundant. This correlation is not unexpected, in view of the localization of reaction product in this cytoplasmic organelle. Preliminary results indicate that there may be a relationship between the amount of immunoreactive AMH present in testicular biopsies of intersex patients and the degree of regression of the Müllerian duct on the ipsilateral side. This may help to elucidate whether persistence of Müllerian ducts results from lack of testicular production of AMH or from peripheral resistance of the Müllerian primordia to the hormone.

Animals↗
PubMed1987

Purified bovine AMH induces a characteristic freemartin effect in fetal rat prospective ovaries exposed to it in vitro.

To determine whether anti-Müllerian hormone (AMH) is responsible for the gonadal lesions observed in bovine genetic females united by placental anastomoses to male twins (freemartins), prospective ovaries of fetal rats were exposed to purified bovine AMH in vitro. In cultures initiated at 14 days p.c. and maintained 3 to 10 days, AMH consistently induced a characteristic 'freemartin effect', namely reduction of gonadal volume, germ cell depletion and differentiation, in the gonadal blastema, of epithelial cells with large clear cytoplasm linked by interdigitations, resembling rat fetal Sertoli cells. These cells tend to become polarized and form cords, delineated by a continuous basal membrane containing laminin and fibronectin. Such structures, resembling developing seminiferous cords, were not detected in control ovarian cultures. These data strongly suggest that AMH is the testicular factor responsible for triggering the morphological abnormalities of freemartin gonads.

Animals↗
PubMed1987

Immunocytochemical study of anti-Müllerian hormone in sheep ovarian follicles during fetal and post-natal development.

Anti-Müllerian hormone (AMH) was detected in perinatal and postnatal sheep ovaries, using avidin-biotin immunohistochemistry with a monoclonal antibody specific for ruminant AMH. Immunoreactivity was limited to granulosa cells, and was influenced both by the degree of follicular development, and by the age of the animal. In the fetus, only the most advanced follicles exhibited a faint immunoreactivity at 120 days gestation, and no reaction was observed in younger animals. Immediately before and after birth, primordial follicles were still negative, but a faint reaction was elicited in young growing follicles, increasing with follicle size. Strong immunoreactivity was visible in antral follicles, especially in the innermost granulosa cell layers, close to the oocyte and lining the antral cavity.

Animals↗
PubMed1986

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.

Amino Acids↗
PubMed1986

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.

Animals↗
PubMed1986

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.

Animals↗
PubMed1986

Monoclonal antibodies raised against bovine anti-müllerian hormone: bovine, ovine, and caprine hormones share a set of identical epitopes.

Monoclonal antibodies (Mabs) have been raised against purified bovine anti-Müllerian hormone (bAMH) in an effort to obtain nonzoospecific reagents. Although the majority of the resulting hybridomas resembled those obtained previously insofar as they recognized only bovine, ovine and caprine AMH, four others, all immunoglobulin Ms, were directed against an epitope shared with AMH of other species, namely rabbit, pig and cat. Both the zoospecific and the conserved epitopes were located close to the site required for biological activity. It is suggested that the similarity between the immunogenic characteristics of bovine, ovine and caprine AMH is in some way related to the fact that AMH in these species is disseminated in the blood stream and may produce freemartinism.

Animals↗