Light and electron microscopic studies on the development and liberation of Janczewskia gardneri Setch. spermatia (Rhodophyta)

Janczewskia spermatia occur in conceptacles and are formed by spermatangial mother cells that originate directly from the inner conceptacular cell layer or from uniseriate filaments. Each spermatangial mother cell produces several spermatangia. Young spermatia are enclosed within an electron dense spermatangial wall and are connected to their respective mother cells by a small septal plug. Reduced chloroplasts are present in the mother cells and in some developing spermatia. As the spermatia mature, the spermatangial wall gelatinizes at the apex of the spermatangium. Subsequently or concomitantly a two-layered spermatial wall forms which ruptures the spermatangium-mother cell pit connection. Rough endoplasmic reticulum aggregates in the posterior end of the spermatium to form spermatial vesicles containing fibrillar material, whereas dictyosome vesicles contribute to the fibrillar material accumulation in later stages. Shortly before or after release from the spermatangial mother cells, the spermatial vesicle becomes extracytoplasmic and a three-layered spermatial wall is formed which gelatinizes and expands to form a mucilage layer that surrounds the spermatia. The pre-fertilization, released spermatia lack a distinct wall, are spherical and possess an intact interphase nucleus, starch grains, numerous dictyosomes, and electron dense bodies of unknown function.