Scarce access to human embryonic and foetal material means our understanding of human retinal development has largely relied on mammalian models, with limited applicability to humans, or on isolated time points. Now, Majlinda Lako and colleagues use comprehensive transcriptome and immunohistochemical analyses to profile early human retinal development at a molecular level, between 4 and 19 weeks post-conception. From these data, the authors define three stages in the development of the human retina, which detail the emergence of specific cell types and transcriptional programmes. Importantly, the researchers analyse splice variants to show that each stage has a specific repertoire of alternatively spliced transcripts. These transcripts, which encode proteins involved in photoreceptor cilia formation, pre-mRNA splicing and epigenetic modifications, can be used to predict the maturation stage of retinal cells generated in vitro. Their study also reveals that transcription of photoreceptor maintenance genes and circular RNAs increases during the process of retina formation, highlighting new interesting factors for future investigation. Overall, these data provide a detailed ‘molecular atlas’ for human retinal development that can be used as a benchmark in the field.
