Morphological Changes in Ascidian Spermatozoa during Fertilization
スポンサーリンク
概要
- 論文の詳細を見る
The ascidian spermatozoa have a small acrosome(s). The acrosome reaction occurs through vesiculation, in fundamentally the same way as observed for mammalian spermatozoa. It occurs in the perivitelline space after passage through the vitelline coat (chorion), which suggests that chorion lysin(s) is associated with the plasma membrane at the apex of the sperm head. In the perivitelline space, apical processes protrude from the peripheral margin of the apex of the acrosome reacted sperm head. Gamete fusion between some of these processes and the egg plasma membrane occurs in the same way that it does in other marine invertebrates, resulting in the incorporation of the sperm into the egg from the anterior tip of its head. These facts suggest that the apical process is functionally homologous to the acrosoamal process(es) of other marine invertebrates. In this respect, fertilization in ascidians has characteristics of both mammals and other marine invertebrates. The acrosomal substance released in the perivitelline space might be an enzyme responsible for the membrane fusion between the apical process and the egg plasma membrane. One of the unique events in ascidian fertilization is that the sperm mitochondrion (paternal mitochondrion) is trapped by follicle cells and discarded outside of the vitelline coat (chorion) during fertilization, which might, in turn, generate the driving force allowing its head to pass through the vitelline coat (chorion). This supposition is reasonable because the chorion lysin(s) might be intercalated, in a non-diffusible state, into the plasma membrane encloslng the aplcal region of the sperm head. In order to develop a satisfactory understanding of the mechanisms that underlie ascidian fertilization, further morphological studies on ascidians with internal fertilization are indispensable.
- 岐阜医療科学大学の論文
著者
関連論文
- The Acrosome and Its Differentiation during Spermiogenesis of a Compound Ascidian Botryllus schlosseri (Ascidiacea, Tunicata)
- Morphological Changes in Ascidian Spermatozoa during Fertilization
- Mitochondrial Translocation in Ascidian Spermatozoa and lts Role in Reproduction