A comparison of the size of gonads between two anuran species during metamorphic climax

American Toad

Bufo americanus

Gosner Stage 46

Leopard Frog

Rana pipiens

Gosner Stage 42

Bufo americanus (transverse section, X150)

Note that the gonad is on the right and the bidders organ is on the left (see below)
Rana pipiens (transverse section, X150)
Undifferentiated gonad (transverse, X600)
Ovary (transverse, X600)
 
Bidder's Organ (transverse, X600)
  
Undifferentiated Gonad (transverse, X600)