Analysis of the gonadal sex of five intersex pigs using Y chromosomal markers

Late-onset vanishing testis-like syndrome in a 38,XX/38,XY agonadic pig (Sus scrofa)

Here we describe the case of a pig with intersex traits including ambiguous external genitalia, sex chromosome abnormalities and a late-onset vanishing testis-like syndrome. It was identified shortly after birth by presenting a predominantly female phenotype with two large scrotal masses resembling testes. The karyotype is 38,XX (53%)/38,XY (47%). Sex steroid levels were undetectable at 1 and 7 months old, whereas circulating cortisol levels were typical. DNA studies excluded gene alterations in sex-determining region Y (SRY), dosage-sensitive sex reversal-congenital adrenal hypoplasia critical region on the X chromosome protein 1 (DAX1), SRY-related high mobility group-box gene 9 (SOX9), nuclear receptor subfamily 5, group a, member 1 (NR5A1), nuclear receptor subfamily 3, group c, member 4 (NR3C4) and steroid 5-alpha-reductase 2 (SRD5A2). At 8 months of age the XX/XY pig evinced delayed growth; however, the most striking phenotypic change was that the testes-like structures completely vanished in a 2-3-week period. The internal genitalia were found to consist of a portion of a vagina and urethra. No fallopian tubes, uterus or remnants of Wolffian derivatives were observed. More importantly, no testes, ovaries, ovotestis or gonadal streaks could be identified. The XX/XY sex chromosome dosage and/or overexpression of the DAX1 gene on the X chromosome in the presence of a wild-type SRY gene may have caused this predominantly female phenotype. This specimen represents an atypical case of 38,XX/38,XY chimeric, ovotesticular disorder of sex development associated with agonadism.

Determination of sex origin of meat and meat products on the DNA basis: a review

Sex determination of domestic animal's meat is of potential value in meat authentication and quality control studies. Methods aiming at determining the sex origin of meat may be based either on the analysis of hormone or on the analysis of nucleic acids. At the present time, sex determination of meat and meat products based on hormone analysis employ gas chromatography-mass spectrometry (GC-MS), high-performance liquid chromatography-mass spectrometry/mass spectrometry (HPLC-MS/MS), and enzyme-linked immunosorbent assay (ELISA). Most of the hormone-based methods proved to be highly specific and sensitive but were not performed on a regular basis for meat sexing due to the technical limitations or the expensive equipments required. On the other hand, the most common methodology to determine the sex of meat is unquestionably traditional polymerase chain reaction (PCR) that involves gel electrophoresis of DNA amplicons. This review is intended to provide an overview of the DNA-based methods for sex determination of meat and meat products.

SRY-negative XX sex reversal in a pony: a case report

A three year old pony with sexually ambiguous external genitalia was found to have a normal female karyotype (64, XX) and bilateral inguinal testes. The PCR analysis of blood samples revealed the absence of the Y chromosome sequences SRY, eTSPY and ZFY. No Y chromosome sequences were identified in DNA extracted from the gonads. The mechanism whereby XX sex reversal occurs in the absence of SRY is unknown.

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.

Intersexuality in pigs: clinical, physiological and practical considerations

Veterinary surgeons and practical pig farmers need to be aware of a condition that can have important deleterious consequences in a breeding herd. The animals in question have sometimes been referred to as hermaphrodites but would more correctly be termed intersexes. Whilst there is a complete spectrum of phenotypic sexual development within a population of such animals, the most common form is that of a putative female with a prominent up-turned vulva. Reflection of the vulval lips reveals a much-enlarged clitoris. There may be scrotal development, in conjunction with an enlarged penile and preputial sheath. Coarse hair and incipient tusk development may further indicate differing degrees of masculinization. Surgical exploration of intersex animals confirms a complete spectrum of gonadal types, ranging from 2 ovaries with a proportion of testicular tissue in one of them (i.e., an ovotestis) to 2, much-enlarged testicular-like structures with no detectable ovarian tissue. The gonads usually remain within the abdomen, but those with testicular tissue may descend to an inguinal or even scrotal location. The genital tract invariably comprises a bicornuate uterus, a partially vestigial Fallopian tube, and some development of one or both Wolffian ducts adjoining an ovotestis or testicular-like structure to form a convoluted epididymis. Spermatozoa are never present, either in abdominal or scrotal testicular tissue, nor are there any germ cells within the seminiferous tubules, only Sertoli-like cells. Due to the spectrum of gonadal types, sexual behaviour ranges from male-type aggressivity on the one hand to regular oestrous cycles on the other, with periods of standing oestrus during which intromission may be achieved. In animals with functional ovarian tissue in both gonads, foetal development has been observed, at least until days 25-30 of gestation. Almost all intersex pigs possess XX sex chromosomes and usually 36 autosomes; only a very small proportion are chimaeras or mosaics. Chromosome banding techniques have failed to demonstrate a portion of the Y chromosome translocated onto an X chromosome nor has molecular probing revealed the presence of the sex determining gene Sry or other classical Y-related DNA sequences, except in one instance. Breeding records suggest that the intersex condition results most frequently from the influence of an autosomal recessive gene carried by certain boars. Identification of such boars is therefore essential, as the incidence of intersexuality in their offspring may reach 4-5% or more. In terms of the pig industry, economic losses may result from: 1. Lack of fertility in intersex animals. 2. Aggressive behaviour in groups of growing/fattening pigs. 3. Boar taint in the carcase of animals possessing ovotestis. 4. Propagation of the deleterious condition, either by mating or more widely by artificial insemination.

Genetic analysis of 38XX males with genital ambiguities and true hermaphrodites in pigs

In pig, the frequency of intersexuality ranges from 0.1 to 0.6%, depending on the breed. In a closed pig herd at INRA an intersex condition was observed in 0.75% of 'females'. The present study describes 11 animals with a 38XX karyotype and the presence of testicular tissue. Phenotypically, all presented with abnormal external or/and internal genitalia. Southern blot analysis with Y-specific probes (SRY and ZFY) revealed the absence of Y material in all animals tested. By polymerase chain reaction (PCR) amplification, 10 of 11 intersex pigs lacked the SRY gene in gonad DNA. These data are compatible with an autosomally (or pseudoautosomally) determined mechanism. Moreover, analysis of familial cases seemed to indicate that 38XX male pseudohermaphrodites and 38XX true hermaphrodites may represent alternative manifestations of the same genetic defect.