(A) January testis. Along the entire length of the testis, the seminiferous lobules filled with bundles of spermatozoa are arranged around the collecting duct, and primary spermatogonia are observed in immature lobules near the efferent ductule.

(B) March testis of a typical aquatic-phase male, showing active breeding behavior. Spermatozoa are very rare in the testicular lobules (whitish areas).

(C) July testis. Highly distended maturing lobules filled with spermatocytes and immature lobules with primary spermatogonia near the efferent ductule are arranged throughout the testis.

Testis-ova occur occasionally in the testicular lobules (Testis-Ova).