Extended Data Fig. 9: Early differentiation and transcriptomic synchronization of optic lobe neurons and summary of the main findings.

a, b, t-SNE visualization of the P15 optic lobe single-cell transcriptomes, using 120 principal components calculated on the log-normalized integrated gene expression. Cells are named by the unsupervised cluster they were assigned to and coloured by the confidence score they received from the neural network (a) or by the log-normalized non-integrated expression of dpn (green), ase (blue), and grim (red) (b). Circles match those of Fig. 3a. c, UMAP visualization of the P15 optic lobe single-cell transcriptomes, using 120 principal components calculated on the log-normalized integrated gene expression. Cells are coloured by the log-normalized non-integrated expression of nerfin-1 (green), Hey (blue), and vfl (red). d, UMAP visualization of Tm3 and T1 cells (above and below the dashed line, respectively) from all stages sequenced in this study, using 25 principal components calculated on the log-normalized non-integrated gene expression. Cells are coloured by their developmental stage. e, Ventral and dorsal transient extrinsic (TE) neurons as well as transient photoreceptors (PRs) line the edges of all optic lobe neuropils and express Follistatin (Fs). Moreover, TE and at least three other neuronal types express Wnt4 in the ventral medulla/lobula but express Wnt10 in the dorsal part of these neuropils. f, The transcriptome of neurons from the same neuronal type but produced days apart converge towards a similar transcriptomic state, which they reach by P30. Moreover, the inter-neuronal type transcriptomic diversity is highest during P40–P70.