THE OOGONIA OF MACROALGA UNDARIA PINNATIFIDA ARE ALKALINE-PHOSPHATASE POSITIVE AND CONTAIN GERMINAL BODY-LIKE STRUCTURES(1).

ABSTRACT

It was observed that in the female gametophyte of Undaria pinnatifida (Harv.) Suringar (Phaeophyta, Laminariales) gametangial initials and maturing oogonia demonstrated different levels of alkaline-phosphatase activity (APA). The oogonia exhibited a higher level of APA than in its initials. Electron-dense granular ovoid structures ∼0.5-0.6 µm were present in the cytoplasm of oogonia. These inclusions were not membrane bound and do not appear to be associated with any particular organelles. The number of the inclusions was 1 to 2 in a single section of the cell. In essential details, the specific APA and subcellular germinal body-like structure of the developing female gamete in U. pinnatifida were very similar to those in metazoan oocytes.