Pathological characteristics of SRY-negative 38,XX-DSD pigs: A family case report

Disorders of sex development (DSD) are congenital conditions characterized by atypical development of chromosomes, gonads, or anatomical sex. XX-DSD pigs disrupt the production of high-quality breeding pigs and impede the advancement of the pig industry. However, the etiology of XX-DSD pigs remains unclear. Systematic reports on the genetic and pathological characteristics of prepubescent XX-DSD pigs in familial contexts are sparse. This study aimed to investigate the genetic and pathological features of one-month-old XX-DSD pigs within a familial context and to provide phenotypic information to elucidate the pathogenic mechanisms of XX-DSD pigs. The findings revealed that inbreeding within the XX-DSD family may contribute to the pathogenesis of XX-DSD pigs. All XX-DSD pigs in the family had a chromosomal sex of female and were male pseudohermaphrodites. The degree of masculinization of the reproductive organs varied among XX-DSD pigs, demonstrating phenotypic heterogeneity. HE staining showed that the testes of prepubescent XX-DSD pigs contained vesicles in the seminiferous tubules, with or without vestigial germ cells. Ultrastructural analyses indicated that sertoli cells, leydig cells and germ cells in the testes of XX-DSD pigs exhibited pathological damage, confirming impaired testicular function. Immunofluorescence staining revealed high expression of SRY-box transcription factor 9 (SOX9) in XX-DSD pig testicular tissues, while forkhead box L2 (FOXL2) was minimally expressed. Disordered secretion of reproductive hormones in prepubescent XX-DSD pigs indicated abnormal hypothalamic-pituitary-gonadal axis (HPGA) function. This study elucidates the genetic and pathological characteristics of prepubescent XX-DSD pigs in familial case, providing valuable insights for further exploration of the pathogenic mechanisms underlying XX-DSD.