Müllerian inhibiting substance is present in embryonic testes of dogs with persistent müllerian duct syndrome

Case report: Persistent Müllerian duct syndrome and enlarged prostatic utricle in a male dog

A 1-year-old male intact Miniature Schnauzer mix was presented for chronic intermittent hematuria. Abdominal ultrasonography revealed a large, fluid-filled cystic structure extending cranially and dorsally to the prostate. Computed tomography scan images revealed that the fluid-filled cavity resembled a uterus, with both horns entering the scrotum through the inguinal canal adjacent to the testes. On cytogenetic analysis, the dog was found to have a homozygote mutation on AMHRII consistent with persistent Müllerian duct syndrome (PMDS). A gonadohysterectomy was performed, and surgical and histologic findings confirmed the presence of a uterus, oviducts, vagina, and testes in this dog. Additionally, an intraoperative fluoroscopy exam revealed a communication between the uterus and the bladder via an enlarged utricle, explaining the hematuria and urine in the reproductive tract (urometra). To our knowledge, this is the first clinical report of a phenotypically intact male dog with PMDS and urometra due to an enlarged prostatic utricle. This case illustrates a combination of a disorder of sex and urogenital sinus development.

Serum anti-Müllerian hormone concentration as a diagnostic tool to identify testicular tissue in canine disorders of sexual development

Disorders of sexual development (DSD) may have their origin in alterations of the chromosomal, gonadal or phenotypic sex. Affected animals are usually presented because of ambiguous external genitalia, seldom because of reproductive disorders. Anti-Müllerian hormone (AMH) is secreted in the gonads with higher amounts in males than in females and can be used to identify gonadal tissue in sexually normally developed dogs. The aim of this study was to examine the diagnostic potential of serum AMH to identify testicular tissue in 11 dogs with DSD. The diagnostic procedures applied were: determination of the phenotypic sex (n = 11), genital ultrasound (n = 9), determination of the SRY gene (n = 11), karyogram (n = 6), gonadectomy (n = 11), pathohistology of the gonads (n = 10), serum AMH measurement (n = 11). 39 female dogs described in a previous study and 19 male dogs with a normal spermiogram served as controls for the AMH serum concentrations in sexually intact dogs. The 11 dogs with DSD were classified as 7 XY DSD and 4 XX DSD. Presumptive testes were obtained in 10 dogs and 1 dog had an ovotestis combined with a testis. Mean serum AMH values of the dogs with DSD were significantly higher (P < 0.001) than in male and female controls. The upper limit of the AMH test (≥ 23ng/ml) was reached in 6 dogs. High AMH concentrations have been described previously in cryptorchid dogs. 1 dog with a male phenotype and 2 with a female phenotype had AMH values within the range of the male controls, although all of them had cryptorchid testes. A Poodle, in which epididymis were identified but no definitive gonads, had an AMH concentration of the lower limit of the test (≤ 0.01 ng/ml), comparable to previously described castrated dogs. This study indicates that serum AMH levels are a useful diagnostic tool to identify testicular tissue in dogs with DSD and suggests the possible use of AMH to diagnose testicular dysgenesis.

A Case of Adenocarcinoma of Uterus Masculinus in a Pomeranian Dog

Introduction: Persistent Müllerian duct syndrome (PMDS), or uterus masculinus, is a rare autosomal recessive form of male pseudohermaphroditism due to the failure of paracrine anti-Müllerian hormone (AMH) secretion by Sertoli cells or failure of the Müllerian ducts to respond to AMH secretion. The malignant degeneration of persistent Müllerian remnants is rare. In human medicine, few related reports exist. In veterinary medicine, this is the first report describing adenocarcinoma of the uterus masculinus involving the prostate in a dog. Clinical history: An 11-year-old, male, neutered Pomeranian dog was referred for computed tomography due to the suspicion of prostatic carcinoma based on ultrasound and cytological examinations. The computed tomography findings were consistent with a uterus masculinus mass with possible prostatic infiltration. Uterus masculinus removal and total prostatectomy were performed; termino-terminal urethral anastomosis was carried out. Dehiscence of the anastomosis was observed 3 days after surgery. The owner declined any further procedures, and the dog was euthanized 5 days after surgery. Histopathological evaluation revealed adenocarcinoma of the uterus masculinus. Conclusion: Adenocarcinoma of the uterus masculinus may occur, suggesting that patients with PMDS should be evaluated for malignant changes of Müllerian remnants.

High prevalence of proposed Müllerian duct remnant cysts on the spermatic duct in wild Eurasian otters (Lutra lutra) from Sweden

The spermatic ducts (vasa deferentia) of 235 otters (Lutra lutra) found dead between 1999 and 2012 in Sweden were examined for presence of paraductular cysts. Single or multiple elongated uni- or bilateral cysts parallel to the spermatic duct were noted in 72% of the examined males. The cysts were adjacent to, but did not communicate with the lumen of the spermatic duct, and were usually located within a few centimeters of the testis and epididymis. The cysts are proposed to be congenital Müllerian duct remnants. Other morphologic abnormalities in the reproductive organs were not noted within this study. Possible causes of the incomplete regression of the embryonic female gonadal duct are exposure to environmental contaminants such as elevated concentrations of estrogen-like compounds (endocrine disrupting chemicals), inbreeding, or a naturally occurring anatomic defect. No obvious geographical pattern was observed for otters with or without cysts. This is the first study and description of cysts on the spermatic duct in otters.

Gonadal and sex differentiation abnormalities of dogs and cats

The molecular steps in normal sexual development were largely discovered by studying patients and animal models with disorders of sexual development (DSD). Although several types of DSD have been reported in the cat and dog, which are often strikingly similar to human DSD, these have been infrequently utilized to contribute to our knowledge of mammalian sexual development. Canine and feline cases of DSD with sufficient evidence to be considered as potential models are summarized in this report. The consensus DSD terminology, and reference to previous terminology, is used to foster adoption of a common nomenclature that will facilitate communication and collaboration between veterinarians, physicians, and researchers. To efficiently utilize these unique resources as molecular tools continue to improve, it will be helpful to deposit samples from valuable cases into repositories where they are available to contribute to our understanding of sexual development, and thus improve human and animal health.

Persistent Mullerian duct syndrome in a Miniature Schnauzer dog with signs of feminization and a Sertoli cell tumour

A 5-year-old male Miniature Schnauzer was presented with unilateral cryptorchidism and signs of feminization. Abdominal ultrasonography revealed an enlarged right testis and a large, fluid-filled cavity that appeared to arise from the prostate. Computed tomography revealed the cavity to be consistent with an enlarged uterine body, arising from the prostate, and showed two structures resembling uterine horns that terminated close to the adjacent testes. The dog had a normal male karyotype, 78 XY. Gonadohysterectomy was performed and both the surgical and the histological findings confirmed the presence of a uterus in this male animal, resulting in a diagnosis of persistent Mullerian duct syndrome (PMDS). The enlarged intra-abdominal testis contained a Sertoli cell tumour. Computed tomography proved to be an excellent diagnostic tool for PMDS.

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.

Disorders of sexual development in the dog and cat

Normal sexual differentiation occurs in three sequential steps--establishment of chromosomal (genetic) sex, development of gonadal sex, and development of phenotypic sex. Errors in the establishment of chromosomal, gonadal, or phenotypic sex cause abnormal sexual differentiation. Affected individuals are identified with a wide variety of patterns from ambiguous genitalia, to apparently normal genitalia with sterility or infertility. When a patient is suspected of having a disorder of sexual development, analysis of the chromosomal constitution and complete gross and histopathologic description of the gonads, internal and external genitalia are required to correctly categorize the type of disorder.

Disorders of sexual differentiation in puppies and kittens: a diagnostic and clinical approach

As in all domestic mammals, sexual differentiation in dogs and cats starts early in the embryonic period prenatally and continues into early postnatal life. The result of such a process is, however, not evident until after puberty,a time when the entire reproductive system undergoes significant changes. Normality of sexual differentiation is difficult to observe in neonates of small animals, with the only gender difference being a slightly longer anogenital distance in male (13-15 mm) versus female (7-8 mm)animals. Early diagnosis of deviations from normality can spare breeders the time and effort devoted to raising an animal that may turn out to be unsuitable for becoming part of the reproductive stock and may spare owners the concern for a pet whose health may be unnecessarily threatened by failing to remove a malformed reproductive system early in life. This article reviews the incidence, clinical and gross anatomic features,and diagnostic approaches that veterinarians can use to address inborn errors of the reproductive system of dogs and cats, highlighting those malformations that bear clinical relevance and may become manifest from birth until puberty.

Sf1 and Mis expression: molecular milestones in the canine sex determination pathway

In mammals, the Y-linked Sry gene is normally responsible for testis induction. However, testes develop in the absence of Sry in human patients and animal models with Sry-negative XX sex reversal. The mechanism of testis induction in this disorder is presently unknown. Characterization of gene expression in normal embryos contributes to the framework within which the canine Sry-negative XX sex reversal model can be evaluated. The objective of this study was to add two molecular milestones to the canine sex determination pathway by determining the temporal and spatial expression patterns of Sf1 and Mis in normal urogenital ridges (UGR) at various gestational stages. The onset of Sf1 expression signifies the start of the sex determination period, whereas initial Mis expression identifies the end of the testis induction period. Sf1 expression in UGR was measured by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and whole mount in situ hybridization (WMISH) at Carnegie stages (CS) 15 to 20. Canine sex determination begins at CS 15 with Sf1 expression in the emerging indifferent gonad. Gonadal Sf1 expression was detected in both sexes at all ages, and in the presumptive adrenal primordium at CS 15 and 17. At stages > or = CS 17, Sf1 expression was pronounced in male and female gonads. Mis expression, assayed by WMISH at CS 13.5-20, was observed only in male gonads > or = CS 18, indicating that the testis induction period ends at CS 18. The expression patterns of both genes are similar to those observed in humans and domestic animals.

Molecular and genetic regulation of testis descent and external genitalia development

Testicular descent as a prerequisite for the production of mature spermatozoa and normal external genitalia morphogenesis, and therefore facilitating copulation and internal fertilization, are essential developmental steps in reproduction of vertebrate species. Cryptorchidism, the failure of testis descent, and feminization of external genitalia in the male, usually in the form of hypospadias, in which the opening of the urethra occurs along the ventral aspect of the penis, are the most frequent pediatric complications. Thus, elucidating the molecular mechanisms involved in the regulation of testis descent and the formation of external genitalia merits a special focus. Natural and transgenic rodent models have demonstrated both morphogenic processes to be under the control of a plethora of genetic factors with complex time-, space-, and dose-restricted expression pattern. The review elucidates the molecular mechanisms involved in the regulation of testis descent and the formation of external genitalia and, wherever possible, assesses the differences between these rodent animal models and other mammalian species, including human.

Sry and Sox9 expression during canine gonadal sex determination assayed by quantitative reverse transcription-polymerase chain reaction

Testis induction is associated with gonadal Sry and Sox9 expression in mammals, and with Sox9 expression in vertebrates where Sry is absent. In mammals, Sry might initiate testis induction by upregulating Sox9 expression; however, direct evidence supporting this hypothesis is lacking. Models of Sry-negative XX sex reversal (XXSR), in which testes develop in the absence of Sry, could provide the link between Sry and Sox9 in testis induction. To define the stages at which testis determination occurs in the canine model, Sry and Sox9 expression were measured in normal urogenital ridges (UGR) and gonads by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Testicular Sry expression rose continuously during canine developmental ages comparable to human carnegie stages (CS) 16-18, with maximal expression at CS 18. Sox9 was expressed in both male and female canine UGR up to CS 17, at which time testis expression became tenfold greater than in the ovary. Although Sox9 was detected by qRT-PCR in ovaries and mesonephroi of both sexes, expression was detected only in canine testes by whole mount in situ hybridization (WMISH). The timing of Sry and Sox9 expression is consistent with a role in testis determination: Sry expression begins at CS 16 in testes, followed by upregulation of Sox9 expression at CS 17. The quantity and temporal and spatial patterns of Sry and Sox9 expression in normal canine gonads are similar to those in humans, sheep, and pigs. These studies should provide the basis for understanding the mechanism of testis induction in the canine model of Sry-negative XXSR.

Müllerian agenesis: etiology, diagnosis, and management

Mullerian agenesis, a congenital malformation of the genital tract is the second most common cause of primary amenorrhea. Its etiology is poorly understood but it may be associated with renal, skeletal, and other abnormalities. The diagnosis is often made either radiologically or laparoscopically in patients in whom hormonal and karyotypic investigations for primary amenorrhea are normal. Two-dimensional ultrasound is not a reliable method of diagnosis, as exemplified by the two cases presented in this review; however, three-dimensional ultrasound may be a more sensitive diagnostic tool. The management is varied, but we conclude that the treatment of choice should be a nonsurgical approach aimed at creating a neovagina. Because of the implications for reproduction, these patients require psychological support, which should be offered as part of therapy.

TARGET AUDIENCE

Gynecologists and Family Physicians

LEARNING OBJECTIVES

After completion of this article, the reader will be able to describe the pathophysiology and clinical presentation of mülerian agenesis and to list the other abnormalities associated with this condition and to outline potential treatment options for a patient with müllerian agenesis.

Persistent paramesonephric ducts (masculine uterus) in the male North American beaver (Castor canadensis)

Remnants of the paramesonephric (Müllerian) ducts can be found in the male as a uterus-like structure. Historically, these have been known as a masculine uterus. We examined the reproductive tracts of 24 male North American beaver, Castor canadensis Kuhl, obtained from trappers between 1980 and 1997 from four areas extending across Ontario. Persistent paramesonephric ducts were found in 20 of these tracts. Prevalence was not related to geographic location. Grossly, the remnant appeared as one or two thin, uterus-like tubes medial to the ducti deferentes, with or without a medial corpus lying between the ampullae. Histologically, the paramesonephric remnants resembled a normal female uterus, but the endometrium consisted primarily of amorphous extracellular matrix. Previous descriptions of the prevalence of the paramesonephric duct remnants (male uterus) in C. canadensis were found to be contradictory.

In vitro fertilization and the effect of progesterone and 17 alpha-hydroxyprogesterone on acrosome reaction of mouse epididymal spermatozoa

This study assessed the effect of progesterone and 17 alpha-hydroxyprogesterone (17 alpha-OH-progesterone) at concentrations of 0.01-10 micrograms/ml, on the acrosome reaction and in vitro fertilizing ability of mouse epididymal spermatozoa. Cumulus masses containing oocytes were cultured in Brinster's medium, to which were added capacitated epididymal spermatozoa which had been incubated in medium with various concentrations of progesterone or 17 alpha-OH-progesterone for 90 min. IVF success rate was assessed 20-24 h following insemination. Progesterone was found to increase the fertilization rate at the 1 microgram/ml and 10 microgram/ml concentrations while lower concentrations had no effect. However, 17 alpha-OH-progesterone failed to show any effect on fertilizing ability. Incubation of epididymal spermatozoa in medium containing 1 microgram/ml and 10 micrograms/ml progesterone significantly increased the acrosome reaction as monitored by a chlortetracycline fluorescence assay. 17 alpha-OH-progesterone, however, failed to show any effect on the acrosome reaction. The results suggest direct effects of progesterone, but not of 17 alpha-OH-progesterone, on fertilization and the acrosome reaction of mouse spermatozoa.

Mullerian-inhibiting substance secretion is delayed in XX sex-reversed dog embryos

Sertoli cell secretion of Mullerian-inhibiting substance (MIS) begins shortly after testis differentiation. Mullerian ducts regress following MIS exposure during an embryonic critical period. In dogs with XX sex reversal, Mullerian ducts persist in the presence of testicular tissue. This study was conducted to determine whether MIS is present in ovotestes of XX sex-reversed embryos during the period for Mullerian duct regression in normal males. XX sex-reversed embryos and normal littermates were identified by a combination of karyotype and gonadal histology. The degree of regression in the adjacent Mullerian duct was scored. Immunohistochemical staining was used to detect MIS in the contralateral gonad. Testicular differentiation and MIS secretion were identified in XY embryos at all ages studied (35-46 days). Seminiferous tubules were not observed in gonads of embryos at risk of XX sex reversal between 35-38 days (n = 15), but were observed at 40 and 46 days (n = 3). Although positive staining for MIS was observed in ovotestes, adjacent Mullerian ducts persisted. The degree of seminiferous tubule development was reduced and MIS secretion was delayed in ovotestes, compared to normal testes. Mullerian duct persistence in this model is apparently due to an abnormality in the quantity and timing of MIS secretion during embryonic development.