ABSTRACT
Gonad and genital pore development was observed on field and cultivated juveniles of the echinoid Paracentrotus lividus. The gonad condition was evaluated by counting the number of acini per gonad following dissection. Presence of the genital pores was determined for each individual, plate by plate, after partial digestion of the tissues. Progressive and relative development was determined. The gonads first appear as a filament which starts to bud and develop acini that eventually fill up with genital material. The pores are pierced from the inside out when the gonads have reached a certain growth stage. Both gonads and pores do not develop simultaneously but in a certain order. In addition, statistical analysis shows that size has more influence on the condition of the genital apparatus than age.
