272
L. G A L L I E N
FIG. 8. Distal part of the deferent duct with the androgenic gland in Orchestia gammarella. P.g., genital papilla; C.d., deferent duct; G.a., androgenic gland. (After
Charniaux-Cotton. )
gametogenesis can be either spermatogenesis or oogenesis for a given
individual, depending upon the phase of activity of the endocrine system
(Figs. 9 and 10). There are not two clearly definable areas, cortex and
medulla, with gynogenic or androgenic inductive potential, respectively, for
differentiation of the gonads, such as is found in tetrapod vertebrates.
However, the possibility is not eliminated that along the length of the
gonad there is a sort of gradient of sensitivity, with the gynogenic potential
higher at the apex and androgenic potential stronger in the posterior region.
FIG. 9. Cross section of an ovary of Orchestia gammarella. Oo., oogonia; Ov., oocyte;
Cf., follicular cells surrounding oocyte, which is laying down yolk. (After CharniauxCotton.)
L. G A L L I E N
FIG. 8. Distal part of the deferent duct with the androgenic gland in Orchestia gammarella. P.g., genital papilla; C.d., deferent duct; G.a., androgenic gland. (After
Charniaux-Cotton. )
gametogenesis can be either spermatogenesis or oogenesis for a given
individual, depending upon the phase of activity of the endocrine system
(Figs. 9 and 10). There are not two clearly definable areas, cortex and
medulla, with gynogenic or androgenic inductive potential, respectively, for
differentiation of the gonads, such as is found in tetrapod vertebrates.
However, the possibility is not eliminated that along the length of the
gonad there is a sort of gradient of sensitivity, with the gynogenic potential
higher at the apex and androgenic potential stronger in the posterior region.
FIG. 9. Cross section of an ovary of Orchestia gammarella. Oo., oogonia; Ov., oocyte;
Cf., follicular cells surrounding oocyte, which is laying down yolk. (After CharniauxCotton.)