Fig. 1
From: Circular RNAs: biogenesis, expression and their potential roles in reproduction
The biogenesis of circRNAs. In the figure, exons are represented by different coloured rectangles and introns are represented by black lines. Exon-derived circRNA (ecRNA) only consists of exons (a and b). circular intronic RNA (ciRNA) contains only introns (c). In exon–intron circRNA (EIciRNA), an intron is inserted between two exons (d). The pathway through which mature ecRNAs migrate into the cytoplasm remains unclear. In this figure, circRNAs are postulated to pass through the nucleus membrane via a nuclear pore complex