a) Gonad cross-section (x260) of yellow eel, 41 cm, 124 g.

Often vermicular appearance of the lobed organ observed at low magnification is considered mistakenly as been a tubular structure of differentiating testes.

b) High magnification (x1040) from Fig. a.

Rows of PGCs (arrows), are separated by the irregular connective tissue. Arteriolae with erythrocytes (Ery) are seen.