Morphological aspects of fertilization in Phallusia (Ascidia) nigra (Ascidiacea, Tunicata)

Fukumoto, Manabu

doi:10.1007/bf00188731

Cited by 3 publications

(3 citation statements)

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“…An accumulation of electron-dense substance was first reported at the apex of the differentiated spermatozoa in Ascidia callosa (Cloney and Abbott 1980). A similar substance (moderately electron-dense material, MEDM) has been observed in the apex of the sperm head of Phallusia nigra (Fukumoto 1993b). Cloney and Abbott (1980) speculated that the dense material in Ascidia callosa sperm had a role in extension of acrosomal filaments, as in acrosome-reacted spermatozoa of other marine invertebrates.…”

Section: Outline Of Spermiogenesismentioning

confidence: 80%

“…During spermiogenesis, they fuse with each other to form an acrosome as observed in S. plicata, Pyura haustor (Fukumoto 1983), and Molgula manhattensis (Fukumoto 1985). In type 3, several proacrosomal vesicles appear in the blister of early spermatids and differentiate without coalescing with each other, resulting in the multiple acrosomal vesicles as observed in Phallusia nigra (Fukumoto 1993b), Ascidia zara, and Ascidia gemmata (Fujii and Fukumoto 1999). During acrosome differentiation in other animal species, proacrosomal vesicles derived from Golgi complexes coalesce to form one acrosomal vesicle (Burgos and Fawcett 1955;Fawcett and Hollenberg 1963;Eckelbarger 1984).…”

Section: Acrosome Differentiationmentioning

confidence: 98%

“…In Ciona intestinalis, the apical substance still remains in its proper location after the acrosome reaction and the formation of apical processes (Fukumoto 1988(Fukumoto , 1990c. In Phallusia nigra, the MEDM also remains in its proper location even after gamete fusion (Fukumoto 1993b). The apical substance in Ciona intestinalis and the MEDM in Phallusia nigra are the first materials that the sperm bring into the egg at fertilization.…”

Section: Outline Of Spermiogenesismentioning

confidence: 99%

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Acrosome differentiation in the ascidians Clavelina lepadiformis and Ciona intestinalis

Fukumoto

2000

Cell and Tissue Research

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The spermatozoa of both Clavelina lepadiformis and Ciona intestinalis have architectural features characteristic of ascidian spermatozoa that have been previously described. They have an elongated head (6 microm and 3 microm long, respectively) and a single mitochondrion that is closely applied laterally to the nucleus; they lack a midpiece. The acrosome of Clavelina lepadiformis spermatozoa is a moderately electron-dense, pear-shaped flattened vesicle, approx. 300 nm x 200 nm x 40 nm in length, width, and height, respectively. The acrosome of Ciona intestinalis spermatozoa is a moderately electron-dense, round flattened vesicle with an electron-dense plate in its central region. It is approx. 200 nm x 200 nm x 50 nm in length, width, and height, respectively. During spermiogenesis in both ascidians, several proacrosomal vesicles (50-70 nm in diameter) appear in a blister at the future apex of the spermatids. These vesicles appear to be associated with the inner surface of the plasma membrane enclosing the blister. They come into contact with each other along the inner surface of the plasma membrane and fuse to form a horseshoe-shaped acrosomal vesicle, which becomes a round, flattened vesicle during further differentiation. Some speculations about the mechanism of acrosome differentiation, the possible role of the acrosome during fertilization, and in the speciation of ascidians are presented.

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Section: Outline Of Spermiogenesismentioning

confidence: 80%