TESHL: TESHL is a testicular germ cell-specific long non-coding RNA (lncRNA) that plays a crucial role in spermatogenesis and the regulation of gene expression in mice [PMC8189594]. Deletion of TESHL in mouse testes resulted in impaired sperm head formation and a distortion of the sex ratio towards females in offspring [PMC8189594]. This deletion also led to the deregulation of distinct sets of sex chromosomal multicopy genes, with up-regulation of X-linked genes and down-regulation of Y-linked genes [PMC8189594]. TESHL interacts with the transcription factor HSF2, but not HSF1, to regulate postmeiotic target genes during spermiogenesis [PMC8189594]. The conserved testicular germ cell-specific lncRNA NR_038002 has been identified as the human ortholog of TESHL, suggesting its potential as a biomarker for diagnosing human infertility [PMC8189594]. TESHL is also involved in maintaining the quality and sex ratio of Y chromosome-bearing sperm [PMC9369125] and plays a role in regulating gene expression on the Y chromosome [PMC8616291]. The temporal pattern of TESHL expression is similar to that of its nearest gene, Tnp1, suggesting coregulation between these two genes during spermatogenesis [PMC8189594]. Overall, TESHL is an important lncRNA involved in spermatogenesis and gene regulation, with potential implications for fertility and offspring sex determination.