. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Figure 6. Comparison of the acrosomal region of the spermatozoa of various vertebrates, (a) Agnathans (Eplalretus hurgeri); (b) agnathans (Liinipclru planm): (c) amphibians (Bulb hnln nipon/ciis); (d) reptiles (Chelonia sp.): (e) birds (Gallus gallits): (l'| mammals (.\fesocnci'tu\ uiirtiiux). b-f were redrawn from Stanley (1967). Voshizaki and Katagiri (1982). Furieri (1970), Okamura and Nishiyama (1978). Yanagimachi and Noda (1970), respectively. Acrosomal vesicle, spotted; perforatorium (subzonal material), shaded: nucleu
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Figure 6. Comparison of the acrosomal region of the spermatozoa of various vertebrates, (a) Agnathans (Eplalretus hurgeri); (b) agnathans (Liinipclru planm): (c) amphibians (Bulb hnln nipon/ciis); (d) reptiles (Chelonia sp.): (e) birds (Gallus gallits): (l'| mammals (.\fesocnci'tu\ uiirtiiux). b-f were redrawn from Stanley (1967). Voshizaki and Katagiri (1982). Furieri (1970), Okamura and Nishiyama (1978). Yanagimachi and Noda (1970), respectively. Acrosomal vesicle, spotted; perforatorium (subzonal material), shaded: nucleus. *; inner acrosomal cap with granular substance (Furieri, 1970), triangles. the head of the hagfish spermatozoon is iim wide in M g/utinosa (Walvig. 1963), about ^m wide (see Results) and urn wide (Walvig, 1963) in /:. hnrgeri, and about nm wide (Jespersen. 1975) and ,um wide (Koch ct 1993) in E. stouti, the spermatozoa could access the egg surface directly. Judging by the fea- tures of the anterior portion of the spermatozoa and the micropyle. the relationship between sperm and egg in hagfish may differ from those in lampreys and teleosts. The exocytosis of the acrosomal vesicle at several points in hagfish (our preliminary observation) as seen in higher vertebrates may be different from the acrosome reaction in sturgeon. The relationship between the existence of egg micropyle and no acrosome in spermatozoa has been considered in teleosts having external fertilization (Bac- cetti and Afzelius. 1976). In hagfish and sturgeon, how- ever, gametes have both structures, although the mode of fertilization in hagfish is still unknown. The structure of the micropyle in hagfish and sturgeon should be studied in detail to understand the role of these structures in fer- tilization. The hagfish has a phylogenetically interesting position in the Chordata. Analysis of sperm function—for exam- ple, the interaction between sperm and egg during fertil- ization
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
