Fig. 1From: Cold seawater induces early sexual developmental stages in the BPG axis of European eel malesIdentified spermatogonia types. Forty times magnification fields of selected histological sections representing the spermatogonia stages: the most undifferentiated spermatogonia type A (SPGAund*; panel a), the second most undifferentiated spermatogonia type A (SPGAund; panel b), differentiated spermatogonia type A cells (SPGAdiff; panel c), and early spermatogonia type B cells (SPGB; panel d). These identifiable characteristics are further labelled with arrows: Blood vessels (Bv), nucleus (Nu), nucleoli (No), Sertoli cells (Sc), Sertoli cell cytoplasmic extensions (Scce), heterochromatin (Hech) and nuage (Nuage)Back to article page