Ultrastructure of germinating tetraspores of Hypnea musciformis (Gigartinales, Rhodophyta)

ABSTRACT

Light and electron (TEM, SEM) microscope studies were carried out on tetraspore release, attachment and germination in Hypnea musciformis (Wulfen) Lamouroux. The attached tetraspores possessed numerous chloroplasts with straight thylakoids lying in parallel rows, and constituting an unusual arrangement, either stacked in granum-like structures, or distributed in concentric forms. Cored vesicles, produced during the fusion stage of sporogenesis, formed fibrillar vacuoles that may have contributed to cell wall construction. The tetraspores germinated immediately after release. They segmented repeatedly, forming a multicellular structure similar to a “morula”. In the daughter cells, the chloroplasts increased in number, and then developed an internal organisation typical of red algae. Germination was associated with organelle proliferation, and with starch mobilisation.

KEY WORDS:

• Hypnea musciformis
• spore germination
• tetraspores
• ultrastructure