Fertilization in Pectinaria (=cistenides) Gouldii

The eggs shed by Pectinaria gouldii were in the stage of primary oocytes with intact germinal vesicles. Maturation began promptly, but proceeded only to the first metaphase, which some eggs reached in 20 minutes, and further progress depended upon sperm penetration. 2. Spermatozoa entered eggs rather more readily after than before breakdown of the germinal vesicle, and only those that entered after the event developed into pronuclei. It is suggested that spermatozoa entering eggs before maturation may be engulfed in a manner resembling phagocytosis, as distinct from membrane fusion. Polar bodies were extruded about 20-25 minutes and 30-35 minutes after semination at 18° C. Male pronuclei were evidently larger than the female. Early prophase of the first cleavage mitosis was seen between 50 and 60 minutes after semination, and cell division took place 20 to 30 minutes later at 18° C. 3. The incidence of polyspermy observed was 24% before and 4% after breakdown of the germinal vesicle. Eggs undergoing refertilization, possible early gynogenesis, and development after failure of polar-body formation were also seen. 4. Oocytes treated with acridine orange displayed green and red cytoplasmic granules, as well as a green zone around the nucleolus. The red fluorescence may have denoted the presence of mononucleotides; the green fluorescence was not considered specific to DNA.