The observation of atypical gonads in land-lacked sea lamprey, larvae from
several streams tributary to the Great Lakes led to this descriptive study
on typical male and female gonads, as well as atypical gonads. Typical male
and female gonads examined in the present study have similar characteristi
cs to those observed in the past; however, larvae with atypical gonads have
some characteristics of both male and female larvae. Many of the atypical
larvae had an unusual number of germ cells, or many atretic oocytes. Based
on quantitative evaluation of several gonadal characteristics of male, fema
le and atypical larvae, it was possible to verify atypical status of 88% of
the larvae which had been qualitatively assigned the atypical sex. Examina
tion of larvae front 15 different populations suggest the proportion of aty
pical larvae is currently much higher in streams tributary to the Great Lak
es, than was previously observed The slowing of gonadogenesis, or the diver
sion of energy for somatic development are possible causes of the? atypical
gonads observed in this study.