English: Zebrafish testis, location on axial view

The axial section of an adult male zebrafish is from the rostral part of the abdominal cavity, where the testis [T] is in the upper part, between swim bladder [sb] and abdominal wall. The area of testis will show largely similar in more caudal sections. The abdominal organs shown in this image are liver [L], pancreas [arrows], spleen [S], intestinal loops [I]. Major blood vessels in this section are dorsal aorta [upper arrow] and posterior cardinal vein [lower arrow], embedded in the kidney [k] intestinal arteries [arrows], intestinal veins [arrows] and epigastric vein [arrow], partly embedded in the liver.

The horizontal skeletogenous septum [horizontal line] separates the epaxialis [em] and hypaxialis muscles [hm], which are inserted to this septum and to the spine [sp], and which are also bound to the skin. In the midline, the epaxial muscles insert to the vertical skeletogonous septum [vertical line]. Although organised in myotomes which are oriented perpendicular to the length axis of the fish, these muscles appear cross-sectioned due to their waved course [middle diagram]. The epaxialis includes the dorsal supracarinalis muscles [upper outline], the hypaxialis includes the ventral infracarinalis muscles [lower outline]. The lateralis superficialis muscles [left/right outlines] overlay the peripheral part of the horizontal septum. Pleural rib structures [arrows] can be observed within the hypaxialis.