scholarly journals THE ACROSOME REACTION IN MYTILUS EDULIS

1965 ◽  
Vol 25 (2) ◽  
pp. 249-259 ◽  
Author(s):  
Lumiko Niijima ◽  
Jean Dan
Keyword(s):  
Mytilus Edulis ◽  
Osmium Tetroxide ◽  
Acrosome Reaction ◽  
Natural Process ◽  
Sperm Head ◽  
The Other ◽  
Membrane Complex ◽  
Acrosomal Membrane ◽  
Anterior Side ◽  
Surrounding Membrane

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.

How does sperm meet egg?--in a marsupial

1994 ◽  
Vol 6 (4) ◽  
pp. 485 ◽  
Author(s):  
WG Breed
Keyword(s):  
Acrosome Reaction ◽  
Small Region ◽  
Sperm Head ◽  
Sminthopsis Crassicaudata ◽  
Acrosomal Membrane ◽  
Wide Range ◽  
A Cell ◽  
Inner Acrosomal Membrane ◽  
Head Morphology ◽  
Range Of Variation

Australian marsupials exhibit a wide range of variation in sperm head morphology, and in thickness of the zona pellucida around the oocyte, suggesting interspecfic differences in the processes of sperm-egg interaction. The observations described here are largely based on the dasyurid Sminthopsis crassicaudata. They show that in oestrous females, after mating, a coagulum forms in the lateral vaginae and, within an hour of insemination, numerous spermatozoa congregate in the isthmus of the oviduct in which the vanguard population undergoes transformation with the head rotating on its axis with the tail to form a T-shape. Once oocytes are released, a few spermatozoa migrate to the higher reaches of the oviduct where sperm-zona binding occurs by way of the plasmalemma over the acrosomal region. The acrosome reaction takes place here and, as the egg rotates, the tail of the spermatozoon becomes parallel to the head. A small region of acrosome sometimes appears to remain intact at this time because spermatozoa with partly intact acrosomes have been found within the zona matrix. In some of these, electron-dense bridges between part of the inner and outer acrosomal membranes which may act as stabilizing structures, were also seen. The zona matrix is tightly packed around the penetrating spermatozoon, but that close to the acrosomal region becomes less electron-dense and more filamentous. Once incorporated into the egg, the spermatozoon lacks a cell membrane around the tail but vesicles close to the sperm head may, at least in part, be remnants of an inner acrosomal membrane. How generally applicable these observations are to other Australian marsupials remains to be determined.

scholarly journals THE ACROSOME REACTION IN MYTILUS EDULIS

1965 ◽  
Vol 25 (2) ◽  
pp. 243-248 ◽  
Author(s):  
Lumiko Niijima ◽  
Jean Dan
Keyword(s):  
Plasma Membrane ◽  
Mytilus Edulis ◽  
Outer Surface ◽  
Sperm Cell ◽  
Acrosome Reaction ◽  
Outer Wall ◽  
Acrosomal Membrane ◽  
General Organization

The intact acrosome of the Mytilus edulis spermatozoon consists of a conical vesicle, the basal side of which is deeply invaginated so that the whole vesicle forms a sheath around a very slender axial rod, about 2.7 µ long, inserted in a tube passing through the nucleus. The annular base of the acrosomal vesical is filled with a homogeneous substance; the outer wall of the vesicle is lined with a somewhat irregular layer of a particulate substance interspersed with very fine tubular elements, and its lumen is nearly filled by a strand of material which extends from the inner tip of the invagination to the apex of the acrosome. The lumen of the invagination appears empty except for the rod and a delicate sleeve-like structure which surrounds it. The plasma membrane of the sperm cell lies in immediate contact with the acrosomal membrane over its whole outer surface. In its general organization, this molluscan acrosome shows a rather close homology with that of the annelid Hydroides.

Organization of the boar spermatozoan plasma membrane: evidence for separate domains (subdomains) of integral membrane proteins in the plasma membrane overlying the principal segment of the acrosome

1987 ◽  
Vol 88 (3) ◽  
pp. 343-349
Author(s):  
R.N. Peterson ◽  
M. Gillott ◽  
W. Hunt ◽  
L.D. Russell
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Acrosome Reaction ◽  
Freeze Fracture ◽  
High Specificity ◽  
Sperm Head ◽  
Integral Membrane Proteins ◽  
Indirect Immunofluorescence Microscopy ◽  
Acrosomal Membrane ◽  
Acidic Phospholipids

Indirect immunofluorescence microscopy and freeze-fracture have been used to identify overlapping subdomains at the peripheral rim of the sperm-head plasma membrane (PM) and the margin of the outer acrosomal membrane (OAM) comprising the principal segment of the acrosome of the boar spermatozoon. An array of ridge-like structures (spaced 12–16 nm centre-to-centre), originally observed on the OAM by Aguas & Pinto da Silva, lies just beneath an area of the PM that is sparsely populated with large intramembranous particles compared to that of other regions of the head PM. This region has a high specificity for the lectin arachis hypogaea (peanut agglutinin). We suggest that the OAM at the rim of the sperm head may be rich in acidic phospholipids and that the close apposition of this membrane with a region of the PM relatively poor in integral membrane proteins may provide sites for initiating the acrosome reaction.

The histochemical localization of acrosin in guinea-pig sperm after the acrosome reaction

1978 ◽  
Vol 32 (1) ◽  
pp. 177-184
Author(s):  
D.P. Green ◽  
A.R. Hockaday
Keyword(s):  
Electron Microscopy ◽  
Guinea Pig ◽  
Acrosome Reaction ◽  
Sperm Head ◽  
Ultrastructural Evidence ◽  
Acrosomal Membrane ◽  
Sperm Penetration ◽  
Inner Acrosomal Membrane ◽  
Dense Marker

The protease acrosin is widely considered to be an essential component of a zona lysin which enables sperm to penetrate the zona pellucida of the egg. Sperm form a characteristic penetration slit little wider than the sperm head itself and this has long suggested that any zona lysin is attached to the sperm surface after an acrosome reaction. This paper provides the first ultrastructural evidence that this is the case. The protein acrosin inhibitor, Kunitz soybean trypsin inhibitor, has been covalently attached to the electron-dense marker, ferritin, and the conjugate incubated with guinea-pig sperm which have undergone an A23187-induced acrosome reaction. Electron microscopy shows that ferritin is distributed unevenly over the outer surface of the newly exposed inner acrosomal membrane but does not extend to the equatorial segment. This is further evidence that acrosin can be considered as a candidate for the role of zona lysin. The mechanism of sperm penetration of the zona is discussed in the light of these observations.

scholarly journals Species-Specific Segregation of Gender-Associated Mitochondrial DNA Types in an Area Where Two Mussel Species (Mytilus edulis and M. trossulus) Hybridize

Genetics ◽  
1996 ◽  
Vol 143 (3) ◽  
pp. 1359-1367 ◽  
Author(s):  
Carlos Saavedra ◽  
Donald T Stewart ◽  
Rebecca R Stanwood ◽  
Eleftherios Zouros
Keyword(s):  
Mytilus Edulis ◽  
The Other ◽  
Allozyme Analysis ◽  
Mussel Species ◽  
Species Origin ◽  
Species Pairs ◽  
Nuclear Background ◽  
Species Specific ◽  
Dna Types ◽  
Fertile Hybrids

Abstract In each of the mussel species Mytilus edulis and M. trossulus there exist two types of mtDNA, the F type transmitted through females and the M type transmitted through males. Because the two species produce fertile hybrids in nature, F and M types of one may introgress into the other. We present the results from a survey of a population in which extensive hybridization occurs between these two species. Among specimens classified as “pure” M. edulis or “pure” M. trossulus on the basis of allozyme analysis, we observed no animal that carried the F or the M mitotype of the other species. In most animals of mixed nuclear background, an individual's mtDNA came from the species that contributed the majority of the individual's nuclear genes. Most importantly, the two mtDNA types in post-F1 male hybrids were of the same species origin. We interpret this to mean that there are intrinsic barriers to the exchange of mtDNA between these two species. Because such barriers were not noted in other hybridizing species pairs (many being even less interfertile than M. edulis and M. trossulus), their presence in Mytilus could be another feature of the unusual mtDNA system in this genus.

scholarly journals KEHAMILAN TETAP SEHAT DI MASA PANDEMI

2021 ◽  
Vol 4 (3) ◽  
pp. 631
Author(s):  
Riona Sanjaya ◽  
Hellen Febriyanti ◽  
Yetty Dwi Fara ◽  
Septika Yani Veronica ◽  
Siti Maesaroh ◽  
...  
Keyword(s):  
Health Education ◽  
Pregnant Women ◽  
Growth And Development ◽  
Natural Process ◽  
Theory And Practice ◽  
The Other ◽  
Normal Length ◽  
Other Hand ◽  
Keywords Pregnancy

ABSTRAKKehamilan merupakan proses yang normal, alamiah yang diawali dengan pertumbuhan dan perkembangan janin intrauteri, dimulai sejak konsepsi sampai bersalin dan lamanya kehamilan normal adalah 280 hari (40 minggu atau 9 bulan 7 hari) di hitung dari hari pertama haid terakhir.Pada masa Kehamilan ibu hamil agar dapat mempersiapkan diri pada kesehatan ibu hamil dengan menjaga nutrisi selama proses kehamilannya. Ibu hamil wajib memeriksakan kehamilannya agara ibu hamil dapat mengetahui dan mencegah sedini mungkin kelainan yang dapat terjadi, meningkatkan kondisi badan ibu dalam menghadapi kehamilan serta mendapatkan penyuluhan yang diperlukan selama kehamilan. Melalui kegiatan ini diharapkan masyarakat khususnya ibu hamil mampu menjaga kesehatannya selama kehamilan di masa pandemi. Kegiatan-kegiatan ini mencakup teori dan praktek yang meliputi : (1) Pendidikan Kesehatan yang dilakukan secara online; (2) Praktik Senam Ibu Hamil yang dilakukan Melalui Vidio; dengan melibatkan mahasiswa Universitas Aisyah Pringsewu pada saat pelaksanaan. Melalui kegiatan ini, diharapkan masyarakat khususnya ibu hamil dapat menyadari pentingnya kesehatan bagi ibu hamil walaupun dimasa pandemi ini. Kata kunci: kehamilan; nutrisi; senam hamil ABSTRACTPregnancy is a normal, natural process that begins with the growth and development of the intrauterine fetus. It starts from conception to delivery and the normal length of pregnancy is 280 days (40 weeks or 9 months 7 days) on the first day of the last menstruation. During pregnancy, pregnant women can prepare themselves for the health of pregnant women by maintaining nutrition during the pregnancy process. Pregnant women are required to have their pregnancy checked so that pregnant women can find out and prevent possible abnormalities that can occur, improve the condition of the mother's body in facing pregnancy and get the necessary counseling during pregnancy. Through this activity, it is expected that the community, especially pregnant women, will be able to maintain their health during pregnancy during a pandemic. These activities include theory and practice as follows: (1) Health Education which will be conducted online; (2) Exercise for Pregnant Women through Video; by involving the students of Aisyah University of Pringsewu during the implementation. In the other hand, it can realize the importance of health for pregnant women even during this pandemic. Keywords: pregnancy; nutrition; pregnancy exercise

Capacity of goat epididymal spermatozoa to undergo the acrosome reaction and subsequent fusion with the egg plasma membrane

1993 ◽  
Vol 5 (3) ◽  
pp. 239 ◽  
Author(s):  
H Harayama ◽  
H Kusunoki ◽  
S Kato
Keyword(s):  
Plasma Membrane ◽  
Acrosome Reaction ◽  
Morphological Changes ◽  
Glass Tube ◽  
Electron Microscopic Examination ◽  
Electron Microscopic ◽  
Acrosomal Membrane ◽  
Sperm Penetration ◽  
Epididymal Spermatozoa ◽  
Caput Epididymidis

The capacity to undergo the acrosome reaction and subsequent fusion with the egg plasma membrane was examined in goat epididymal spermatozoa. Spermatozoa from the proximal and distal caput and distal cauda were preincubated in a sealed glass tube for induction of the acrosome reaction, and their viability, acrosome morphology and penetrability into zona-free hamster eggs were determined. A simplified triple-stain technique revealed that most of the preincubated live spermatozoa in the samples from the distal caput and distal cauda epididymides underwent morphological changes that indicated the occurrence of the acrosome reaction. Electron microscopic examination revealed that the outer acrosomal membrane of many spermatozoa in these samples showed fusion at multiple sites to the plasma membrane. However, the rates of acrosome-reacted cells in the proximal caput spermatozoa were still lower. The sperm penetration assay demonstrated that the penetration rates of distal caput and distal cauda spermatozoa preincubated for 2 h were 93% and 74% respectively, whereas proximal caput spermatozoa scarcely penetrated into eggs. These results indicate that increasing numbers of goat spermatozoa improve in the functions related to the acrosome reaction and subsequent fusion with the egg plasma membrane during their transit through the caput epididymidis.

The influence of heavy infestations of Polydora ciliata on the flesh content of Mytilus edulis

1979 ◽  
Vol 59 (2) ◽  
pp. 289-297 ◽  
Author(s):  
R. M. L. Kent
Keyword(s):  
Water Content ◽  
Mytilus Edulis ◽  
Dry Weight ◽  
Condition Index ◽  
The Body ◽  
The Other ◽  
Mantle Tissue ◽  
Polydora Ciliata ◽  
Weight Condition ◽  
Body Components

The dry weight condition index and water content of two groups of mussels, one with heavy infestations and the other with mild infestations of Polydora ciliata, were determined over a period of 15 consecutive months. The results were seasonally variable, but for most months the heavily infested mussels had a condition index significantly lower, and a water content significantly higher, than the mildly infested mussels. This suggests that heavy infestations of P. ciliata are associated with reduced flesh content in mussels.Further analyses of the body components of the two groups of mussels, showed that the mantle tissue of heavily infested mussels was reduced much more than the nonmantle tissue. Since the mantle is the main repository of gametes, this suggests that heavy infestations of P. ciliata might lower the fecundity of mussels.

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