Fig. 1

a Reproductive tract of a female Raja clavata at the actively spawning stage. The measurements made on the OGs are represented: w width, h height, t thickness. b External anatomy of the OG at the actively spawning stage. Anteriorly, the OG communicates with the oviduct, while posteriorly it communicates with the uterus. The dotted line in the centre indicates the position of sagittal sectioning. c Sagittal section of the OG at the actively spawning stage, showing the different zones from anterior to posterior: club zone; papillary zone; baffle zone; terminal zone. d Internal view of the two halves of the OG at the actively spawning stage, displaying the different gland zones, from the oviduct to the uterus: club zone; papillary zone; baffle zone; terminal zone. e Dorsal view of an egg capsule, the surface of which is covered with hairs. O ovary, F follicles, OG oviducal gland, C capsule, U uterus, Ov oviduct, Cz club zone, Pz papillary zone, Bz baffle zone, Tz terminal zone