Fig. 1
Morphological characteristics of zebrafish type A undifferentiated (Aund) and type A differentiating (Adiff) and type B spermatogonia and Leydig cells and in situ hybridization for insl3 mRNA in adult zebrafish testis. a Type Aund spermatogonia (arrow) are single germ cells showing a large and clear nucleus, with poorly condensed chromatin and one or two compact nucleoli. b A cyst containing two type Adiff spermatogonia (arrowhead) that show smaller nuclei stained more intensely by toluidine-blue. Type B spermatogonia (thin arrow) have still smaller, slightly elongated/ovoid nuclei that moreover show a high amount of heterochromatin. c Interstitial space (dashed line) with a group of Leydig cells. d Adult zebrafish testis section showing the detection of insl3 mRNA by in situ hybridization in Leydig cells cluster (dashed lines). Inset in d non-specific staining obtained with the sense probe. a-c Sections were prepared for morphological analysis according to Leal et al. (2009b). Magnification ×1000 (a, b), ×600 (c, d). Bars 10 µm