Testicular fetal Leydig cells produce androgens essential for male reproductive development. Impaired fetal Leydig cell differentiation leads to differences of sex development including hypospadias, cryptorchidism, and infertility. Despite fetal Leydig cells are thought to originate from proliferating progenitor cells in the testis interstitium, the precise mechanisms governing the interstitial cells to fetal Leydig cell transition remain elusive. Using mouse models and single-nucleus multiomics, we find that fetal Leydig cells arise from a Nr2f2-positive interstitial population. Embryonic deletion of Nr2f2 in mouse testes results in differences of sex development, including dysgenic testes, Leydig cell hypoplasia, cryptorchidism, and hypospadias. By combining single-nucleus multiomics and NR2F2 ChIP-seq we find that NR2F2 promotes the progenitor fate while suppresses Leydig cell differentiation by modulating key transcription factors and downstream genes. Our findings establish Nr2f2 as a crucial regulator of fetal Leydig cell differentiation and provide molecular insights into differences of sex development linked to Nr2f2 mutations.

The patient, assigned female at birth and aged 1 year and 7 months, presented with clinical manifestations of 46,XY disorders of sex development. The external genitalia exhibited a severely undermasculinized phenotype. Laboratory tests and gonadal biopsy indicated poor Leydig cell function and good Sertoli cell function. Genetic testing revealed compound heterozygous mutations of c.867-2A>C and c.547G>A (p.G183R) in the LHCGR gene. The patient was ultimately diagnosed with type II Leydig cell hypoplasia. Type II Leydig cell hypoplasia presents a broad spectrum of clinical phenotypes, characterized by a lack of parallel function between Leydig cells and Sertoli cells, and significant individual variability in spermatogenesis and gender assignment. This condition should be considered when there is poor Leydig cell function but good development of Wolffian duct derivatives. 患儿，社会性别女性，1岁7个月，临床表现为46,XY性发育异常，外生殖器呈重度男性化不全表型，实验室检查及性腺活检提示睾丸间质细胞功能差而支持细胞功能良好，基因检测发现LHCGR基因存在c.867-2A>C及c.547G>A（p.G183R）复合杂合变异，最终诊断为Ⅱ型间质细胞发育不全。Ⅱ型间质细胞发育不全临床表型谱广，睾丸间质细胞与支持细胞功能不平行，生精功能及性别选择个体化差异大，当睾丸间质细胞功能差而华氏管发育良好时需考虑该病。.

Complete androgen insensitivity syndrome (CAIS) is a rare X-linked recessive disorder of sex development (DSD) caused by androgen receptor (AR) gene mutation and present with female phenotypes with male chromosomal karyotype. Primitive bipotent gonads in CAIS differentiate into testes producing androgens and antimüllerian hormone (AMH). However, androgens cannot stimulate embryonic wolffian ducts into male internal reproductive organs owing to AR defect and hormone resistance, while AMH induces the regression of müllerian ducts with the absence of uterus, fallopian tubes, and upper third of the vagina. Thus, with male sex chromosome and testes, individuals with CAIS present with a typical female phenotype, primary amenorrhea (PA) and infertility, spontaneous thelarche during puberty, absent or sparse axillary/pubic hair, and increased risk of gonadal tumors in cryptorchidism. Though theoretically CAIS can be screened prenatally through a discrepancy between chromosomal karyotype and fetal external genitalia, suspected in bilateral inguinal "hernia" cases with female genital phenotype, and considered in cases with elevated testosterone (T) levels but no signs of virilization, the lack of typical symptoms brings great challenges to diagnosis and management. Endocrinological hormone assay is helpful for the identification of CAIS which reveals normal or elevated T levels, elevated luteinizing hormone for impairment of negative feedback of T, and normal follicle-stimulating hormone which is regulated by both sex hormones and inhibin. The diagnosis of CAIS after puberty is similar to the diagnostic workflow of PA with additional tests and should be differentiated with PA-related etiologies and other kinds of DSD, such as Swyer syndrome, Mayer-Rokitanskey-Küster-Haüser syndrome, Leydig cell hypoplasia, and several steroidogenic enzymatic deficiencies. Clinical manifestations, hormonal profiles, chromosomal karyotype, and pelvic imaging can provide comprehensive information for diagnosis. AR gene test or binding capacity can be performed for definitive diagnosis. The management of CAIS includes gonadectomy, hormone supplementation, and psychological support and education. Although with the development of molecular biology and awareness of the clinical entity more cases were reported, diagnostic and management challenges exist due to the disease-related and treatment-related stress including the rarity, untypical clinical manifestations, increased risk of gonadal malignancy, and its influence on physiology and psychology. This review provides a comprehensive overview of the molecular pathogenesis, pathophysiology, diagnostic evaluation, differential diagnosis, and management of CAIS.

Male infertility, often attributed to insufficient production of healthy and active sperm, can be exacerbated by electromagnetic radiation emitted from mobile phones, which disrupts normal spermatogenesis and leads to a notable decline in sperm quality. The main targets of mobile phone-induced damage in the testes are Leydig cells, seminiferous tubules, and sperm cells. The aim of this systematic literature review is to identify histopathological changes in the testes due to mobile phone radiation exposure and to examine its effects on sperm parameters in experimental animals. In this systematic review, an extensive literature search was conducted across databases such as PubMed, ScienceDirect, Hinari, and Google scholar. A total of 752 studies were identified for screening, and 18 studies were deemed eligible for data extraction. Studies have identified histopathological alterations in testicular tissue caused by mobile phone radiation, such as reduced seminiferous tubule diameter, tunica albuginea and germinal epithelial thickness, Leydig cell hypoplasia, and increased intertubular space. Consistent exposure to mobile phone radiation has been shown to significantly reduce sperm count, motility, and viability, while also increasing abnormal sperm morphology in male rats, mice, and rabbits. Animal studies indicate that electromagnetic radiation from mobile phones can negatively impact testicular tissue and sperm parameters, including sperm count, motility, viability, and morphology. As a precaution, preventive measures are recommended to minimize potential risks from mobile phone exposure, and further research is needed to fully understand its effects on human reproductive health.

Testicular fetal Leydig cells are a specialized cell type responsible for embryo masculinization. Fetal Leydig cells produce androgens, that induce the differentiation of male reproductive system and sexual characteristics. Deficiencies in Leydig cell differentiation leads to various disorders of sex development and male reproductive defects such as ambiguous genitalia, hypospadias, cryptorchidism, and infertility. Fetal Leydig cells are thought to originate from proliferating progenitor cells in the testis interstitium, marked by genes like Arx , Pdgfra , Tcf21 and Wnt5a . However, the precise mechanisms governing the transition from interstitial cells to fetal Leydig cells remain elusive. Through integrated approaches involving mouse models and single-nucleus multiomic analyses, we discovered that fetal Leydig cells originate from a Nr2f2 -positive non-steroidogenic interstitial cell population. Embryonic deletion of Nr2f2 in mouse testes resulted in disorders of sex development, including dysgenic testes, Leydig cell hypoplasia, cryptorchidism, and hypospadias. We found that NR2F2 promotes the progenitor cell fate while suppresses Leydig cell differentiation by directly and indirectly controlling a cohort of transcription factors and downstream genes. Bioinformatic analyses of single-nucleus ATAC-seq and NR2F2 ChIP-seq data revealed putative transcription factors co-regulating the process of interstitial to Leydig cell differentiation. Collectively, our findings not only highlight the critical role of Nr2f2 in orchestrating the transition from interstitial cells to fetal Leydig cells, but also provide molecular insight into the disorders of sex development as a result of Nr2f2 mutations.