Abstract
Suspensions of Mytilus edulis eggs were fixed with osmium tetroxide at various intervals between 1 and 10 seconds after heavy insemination, and sectioned for electron microscopy to follow the natural process of acrosome reaction in the spermatozoa around the eggs. Sperm suspensions were also fixed after the addition of 10 per cent by volume of M/3 calcium chloride. Within the first second after the acrosome is stimulated to react, an opening appears at its apex, around which the plasma and acrosomal membranes fuse to each other, and the resulting membrane complex is reflected backward, presumably by the swelling of material lining it. At the same time the other material within the now open vesicle disappears, and the rudiment of the acrosomal process, consisting of a short axial rod loosely surrounded by the invaginated part of the acrosomal membrane, is exposed at the anterior side of the sperm head. Within another second this rudiment is extended by elongation of the axial rod and expansion of the surrounding membrane. If the spermatozoon has reacted close to the egg surface, the elongation may be very slight, whereas in suspended spermatozoa the process may reach a length of 13 µ. Possible mechanisms underlying these changes are suggested.
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Selected References
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- COLWIN A. L., COLWIN L. H. Changes in the spermatozoon during fertilization in Hydroides hexagonus (Annelida). II. Incorporation with the egg. J Biophys Biochem Cytol. 1961 Jun;10:255–274. doi: 10.1083/jcb.10.2.255. [DOI] [PMC free article] [PubMed] [Google Scholar]
- COLWIN A. L., COLWIN L. H. Fine structure of the spermatozoon of Hydroides hexagonus (Annelida), with special reference to the acrosomal region. J Biophys Biochem Cytol. 1961 Jun;10:211–230. doi: 10.1083/jcb.10.2.211. [DOI] [PMC free article] [PubMed] [Google Scholar]
- COLWIN L. H., COLWIN A. L. Changes in the spermatozoon during fertilization in Hydroides hexagonus (Annelida). I. Passage of the acrosomal region through the vitelline membrane. J Biophys Biochem Cytol. 1961 Jun;10:231–254. doi: 10.1083/jcb.10.2.231. [DOI] [PMC free article] [PubMed] [Google Scholar]
- DAN J., OHORI Y., KUSHIDA H. STUDIES ON THE ACROSOME. VII. FORMATION OF THE ACROSOMAL PROCESS IN SEA URCHIN SPERMATOZOA. J Ultrastruct Res. 1964 Dec;11:508–524. doi: 10.1016/s0022-5320(64)80079-4. [DOI] [PubMed] [Google Scholar]
- NIIJIMA L., DAN J. THE ACROSOME REACTION IN MYTILUS EDULIS. I. FINE STRUCTURE OF THE INTACT ACROSOME. J Cell Biol. 1965 May;25:243–248. doi: 10.1083/jcb.25.2.243. [DOI] [PMC free article] [PubMed] [Google Scholar]
- ROSENBLUTH J. Contrast between osmium-fixed and permanganate-fixed toad spinal ganglia. J Cell Biol. 1963 Jan;16:143–157. doi: 10.1083/jcb.16.1.143. [DOI] [PMC free article] [PubMed] [Google Scholar]
- WADA S. K., COLLIER J. R., DAN J. C. Studies on the acrosome. V. An egg-membrane lysin from the acrosomes of Mytilus edulis spermatozoa. Exp Cell Res. 1956 Feb;10(1):168–180. doi: 10.1016/0014-4827(56)90083-0. [DOI] [PubMed] [Google Scholar]