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At least 19 recordsLinked to original sources
PubMed1977

Sperm/egg interaction: the specificity of human spermatozoa.

Human spermatozoa display unusually limited affinities in their interaction with oocytes of other species. They adhered to and, when capacitated, penetrated the vestments of the oocyte of an ape--the gibbon, Hylobates lar--both in vivo and in vitro. On the other hand, human spermatozoa would not even attach to the zona surface of sub-hominoid primate (baboon, rhesus monkey, squirrel monkey), nor to the non-primate eutherian oocytes tested. Among the apes the gibbon stands furthest from man. Thus, although the specificity of human spermatozoa is not confined to man alone, it probably is restricted to the Hominoidea. This study also suggests that the evolution of man and perhaps the other hominids has been accompanied by a restrictive change in the nature of the sperm surface which has limited and made more specific the complementary surface to which their spermatozoa may adhere. For the failure of human spermatozoa to attach to the zona surface of all non-hominoid oocytes stands in contrast to the behaviour of spermatozoa of the several other mammals studied which, in most combinations, adhered readily to foreign oocytes, including those of man. Taxonomically, the demonstration of a compatibility between the gametes of man and gibbon, not shared with cercopithecids, constitutes further evidence for inclusion of the Hylobatidae within the Hominoidea.

Animals↗
PubMed1977

Involvement of a trypsin-like activity in sperm penetration of zona-free mouse ova.

The presence of trypsin inhibitors during insemination reduced penetration of zona-intact and zona-free mouse ova by capacitated sperm. This inhibition was dependent upon both concentration of inhibitor and sperm. Preincubation of gametes in inhibitors did not markedly influence their subsequent fertility, nor did it alter sperm motility. Trypsin inhibitors may exert an effect on penetration by interfering with the induction of the sperm acrosome reaction or with the process of sperm-egg fusion.

Amidines↗
PubMed1977

Alteration of structure and penetrability of the vitelline envelope after passage of eggs from coelom to oviduct in Xenopus laevis.

The vitelline envelope (VE) that surrounds an egg released from the ovary into the coelom of Xenopus laevis differs markedly, in structure and penetrability, from the VE surrounding an oviposited egg. In a coelomic egg, the filaments that form the VE are arranged in distinct fascicles or bundles. The exterior surface of the VE is irregular in contour and is permeated by channels. In an oviposited egg, the filaments are evenly dispersed and lack a fasciculated arrangement; the exterior surface is smooth and no channels are present. The fascicular arrangement of fibrils in the coelomic VE is maintained only at neutral pH, and is not visibly altered by the cortical reaction. VEs from coelomic eggs retain their fasciculated morphology after isolation from the egg. In an in vitro test system, sperm penetrated VEs isolated from oviposited eggs, but failed to penetrate VEs isolated from coelomic eggs. The structural transformation of the VE from the coelomic type to the oviposited type occurs in the first 1-cm segment of the oviduct, prior to addition of jelly to the egg. Neither intact jelly, solubilized jelly, nor jelly extracts were capable of altering the structural organization of coelomic VEs, suggesting that the structural transformation of the VE is effected by some oviducal factor other than jelly.

Animals↗
PubMed1978

Penetration of the zona-free or intact eggs by foreign spermatozoa and the fertilization of deer mouse eggs in vitro.

Zona-free eggs were introduced to fresh or preincubated sperm suspensions and the penetration of eggs by foreign spermatozoa was examined, as evidenced by enlargement of the sperm head and formation of the male pronucleus. It was found that zona-free hamster eggs can be penetrated by guinea-pig, deer mouse and rabbit spermatozoa but zona-free rat, mouse and rabbit eggs cannot be penetrated by guinea-pig spermatozoa. Furthermore, zona-free rat and mouse eggs cannot be penetrated by spermatozoa from two species of deer mice and the Mongolian gerbil. The zona pellucida of a few intact rat eggs can be penetrated by mouse (6%) and by P. leucopus spermatozoa (14%) but enlargement of the sperm head and formation of pronuclei were observed in the former but not in the latter. It seems that (1) sperm capacitation is required for the penetration of zona-free eggs, (2) the attachment of foreign spermatozoa to eggs may indicate their potential ability of penetration in some cases, (3) there is a certain affinity between the vitellus of one species and spermatozoa from another species, (4) the block to the entry of foreign spermatozoa is not only in the zona pellucida but also in the vitelline membrane, (5) zona-free hamster eggs can be penetrated by spermatozoa of six species, (6) mouse spermatozoa can penetrate zona-free eggs of three species, and (7) fertilization of intact P. maniculatus eggs can be achieved in vitro.

Animals↗
PubMed1978

Timing of sperm transport, sperm penetration and cleavage in the rat.

Times of sperm entry into the oviduct from the uterus, into the ampulla from the isthmus; of sperm penetration into oocytes, and of cleavage, were determined using three mating regions. Time intervals and their errors of estimation were calculated. Spermatozoa were first found in the isthmus of the oviduct no earlier than 15 minutes after coitus, but required four hours to ascend the oviduct to the ampulla. The rate of sperm arrival was equal to the rate of sperm penetration, i.e., about 3 sperms/hour. Time of cleavage in vivo was 20.6 hours after sperm penetration in ad libitum mated animals. In culture, oocytes cleaved at exactly the same time as in vivo. Delaying sperm arrival to the site of fertilization (by delaying mating) shortened the time interval between median time of sperm penetration and median time of cleavage. It was concluded that the time of cleavage of the oocyte reflects primarily the time of sperm penetration, but is also influenced by the postovulatory age of the oocyte.

Animals↗
PubMed1978

Electron microscopic observation on sperm penetration and pronuclear formation in the fish egg.

Unfertilized eggs of the medaka, Oryzias latipes were inseminated after being mechanically freed from the chorion. In the first step of penetration, as soon as it reached the vitelline surface, the whole spermatozoon was quickly enclosed by ooplasmic protrusions (fertilization cone) of the vitelline surface. In the second step, the egg plasma membrane fused with various regions of the plasma membrane of the enclosed spermatozoon; finally the sperm flagellum was also incorporated into the ooplasm. Initial disappearance of the nuclear envelope of the sperm with vesiculation at the apical region of the head is followed by dispersal of the sperm chromatin. The nuclear envelope is then reformed by fusion of elongated or flattened vesicles along the margin of dispersing nuclear chromatin. The mature male pronucleus has a large nucleolus within a wrinkled envelope. It seems that the fertilization process in this fish involves some features of that occurring in the marine invertebrate and the mammalian eggs.

Animals↗
PubMed1978

Temperature dependence of sperm-egg fusion and post-fusion events in hamster fertilization.

The effects of temperature (4--37 degrees C) on sperm-egg fusion and the post-fusion events were studied. At 4--10 degrees C, acrosome-reacted spermatozoa bound to egg plasma membranes, but could not fuse with them. At 25 degrees C or above, both binding and fusion took place. The post-fusion events could occur over a broad temperature range (4--37 degrees C) but the events progressed faster with increasing temperature. An abnormal development of egg pronucleus, possibly due to an incomplete functioning of the meiotic spindle mechanism, was observed in eggs inseminated at 37 degrees C and cultured at 25 degrees C.

Animals↗
PubMed1978

Rate of egg penetration in vitro accelerated by T/t locus in the mouse.

Spermatozoa from fertile mice heterozygous for tw32, a recessive lethal allele of the T/t locus, were compared to normal spermatozoa in a fertilization in vitro system. The rate of egg penetration following insemination in vitro was determined for epididymal spermatozoa from C57BL/6-tw32/+ mice and for epididymal spermatozoa from C57BL/6-+/+ mice. At one hour after insemination, the mean of penetration +/- standard deviation for spermatozoa from BL/6-tw32/+ mice was 20% +/- 2.1 (109 eggs observed, 5 experiments), while the mean for spermatozoa from BL/6-+/+ mice was 1% +/- 1.5 (107 eggs observed, 4 experiments). By five hours post-insemination, the levels of egg penetration were not significantly different. These results suggest that tw32 increases the initial rate of egg penetration. Preliminary observations of sperm motility and sperm-egg association at one hour post-insemination in vitro do not support the hypothesis that this earlier penetration is due to improved sperm progress to the egg. Rather, the earlier penetration may be a result of changes in the timing of capacitation, the acrosome reaction, or sperm-egg fusion. It is possible that the earlier penetration may play a role in the distortion of the transmission ratio of tw32.

Animals↗
PubMed1979

In vitro fertilization of two species of deer mouse eggs by homologous or heterologous sperm and penetration of laboratory mouse eggs by deer mouse sperm.

Newly ovulated eggs from immature deer mice (Peromyscus maniculatus and P. polionotus) and mature laboratory mice (Mus musculus) treated with PMSG and HCG were inseminated in vitro with spermatozoa recovered from the cauda epididymidis of mature males. The time required for capacitation of deer mouse sperm in culture was estimated to be about two to five hours based on the dispersal of sperm agglutination and increase of sperm motility. The rate of sperm penetration through the zona pellucida of deer mouse eggs by homologous or heterologous sperm was relatively high (72-91%) but that of laboratory mouse eggs by deer mouse sperm was low (20-21%). After penetration through the zona pellucida, a high proportion of deer mouse eggs (79-93%) were fertilized by homologous or heterologous deer mouse sperm but no laboratory mouse eggs were fertilized by sperm of two species of deer mice. The zona pellucida was dissolved in a higher proportion of laboratory mouse eggs cultured with P. maniculatus (45%) than with P. polionotus sperm (3.4%), but this did not happen by incubation of deer mouse eggs with homologous or heterologous sperm. It seems that there is little difference in sperm penetration and fertilization between these two closely related species of deer mice but the reactions between the mouse eggs and deer mouse sperm are quite different.

Animals↗
PubMed1979

An ultrastructural study of epididymal mouse spermatozoa binding to zonae pellucidae in vitro: sequential relationship to the acrosome reaction.

Mouse sperm bind to the zona pellucida of the egg prior to penetration of the zona and entry into the perivitelline space. The question then arises: when does the acrosome reaction occur relative to these processes? An ultrastructural study of mouse epididymal sperm bound to the surface of the zona and in the privitelline space was undertaken to clarify this point. Cumulus-free mouse eggs were inseminated in either a complete defined culture medium capable of supporting in vitro fertilization or in Tris/NaCl buffer containing Ca+2. Both media support sperm binding to the zona to the same extent; binding is complete in 15 minutes. Unbound sperm were removed by a step gradient density centrifugation to yield a preparation of eggs with sperm firmly bound. All sperm in the perivitelline space had undergone the acrosome reaction. Sperm bound at the surface of the zonae pellucidae of eggs recovered at ten minutes after insemination all had intact acrosomes. At 40 minutes after insemination, half of the sperm were intact; the other half were in the initial stages of the acrosome reaction. At 90 minutes after insemination, 12% of the sperm had undergone the full acrosome reaction and were starting to penetrate the zona; of the balance, half were in various stages of the acrosome reaction, while half were still intact. These findings support the hypothesis that the sequence of the early reactions leading to fertilization in the mouse is: intact sperm binding to zona; acrosome reaction at the zona surface; penetration of the zona.

Acrosome↗
PubMed1979

Prevention of in vitro fertilization of canine oocytes by anti-ovary antisera: a potential approach to fertility control in the bitch.

Antisera raised against canine ovaries were found to induce light scattering of the surface of the egg zona pellucida even when diluted 10,000 times, and to delay digestion of the zona by pronase. High concentrations of antiserum were required, however, to inhibit in vitro fertilization of the oocytes. Absorption of the antisera with canine ovaries removed these effects, whereas absorption with liver, uterus and serum did not. These results demonstrate the antigenicity of the canine ovary and suggest the plausibility of an anti-zona pellucida vaccine for bith control in the bitch.

Animals↗
PubMed1979

Injection of sperm heads into immature rat oocytes.

When sperm heads are injected into rat oocytes at the germinal vesicle stage the sperm heads remain intact until the germinal vesicle breaks down. Then they decondense but do not form pronuclei. This observation agrees with the results reported for in vitro fertilization of immature oocytes from rats, mice and hamsters.

Animals↗
PubMed1979

Polyspermy-preventing mechanisms in mouse eggs fertilized in vitro.

The time sequence of the mechanisms that prevent polyspermy in cumulus-free mouse eggs was determined by continuous micropscopic observations during in vitro fertilization. The zona reaction had begun, and the vitelline surface block to polyspermy was established, in less than one minute following sperm fusion with the vitellus. In less than five minutes, the zona reaction had advanced to the stage that no more spermatozoa could become firmly attached to the surface of the zona pellucida.

Animals↗
PubMed1979

Failure of human spermatozoa to penetrate zona free mouse and rat ova in vitro.

When incubated for 8 to 26 hours with zona-free mouse or rat ova, human spermatozoa failed to attach to or penetrate any of the ova. The ova were capable of being fertilized since both intra- and inter-species penetration of spermatozoa and formation of pronuclei occurred between rat and mouse gametes. When mouse spermatozoa were incubated for three to eight hours with rat ova, a high proportion of the ova were penetrated, formation of pronuclei occurred and in 9 out of 36 ova incubated for 40 hours after insemination, regular cleavage and formation of morphologically normal 2-cell embryos occurred. Human spermatozoa retained their morphological integrity and motility only when the culture medium contained purified bovine serum albumin (3 mg/ml) or human serum (5% v/v) and not when unpurified BSA from several different commercial sources was used as a protein source. In this latter medium, the ova of both rats and mice degenerated after 8-hour incubation in the presence of human spermatozoa but not when human spermatozoa were absent or in the presence of either rat or mouse spermatozoa. Electron microscopy indicated that the human spermatozoa incubated for eight hours in medium containing purified BSA had undergone an acrosome reaction. These spermatozoa also attached to and penetrated human oocytes which had been matured in vitro.

Animals↗
PubMed1978

Penetration of spermatozoon into the ovum and transformation of the sperm nucleus into the male pronucleus in the domestic fowl, Gallus gallus.

The apex of the sperm head which has undergone the acrosome reaction comes in contact with the plasma membrane of the ovum. After the entire surface of the inner acrosomal membrane has come into close contact with the plasma membrane of the ovum, the two membranes fuse to form a continuous membrane. All parts of the spermatozoon that are devoid of plasma membrane penetrate into the ooplasm. As the head of the spermatozoon moves deeper into the ooplasm, the chromatin begins to disperse, and the head of spermatozoon is transformed into a large spherical nucleus with low electron density. At a later stage of the transformation, many small vesicles appear around the nucleus and subsequently fuse to form two continuous membranes. These membranes represent the male pronuclear envelope. The condensation of the chromatin occurs in places in the nucleus, so that the male pronucleus is formed. During the course of the formation of the male pronucleus, the subacrosomal rod and tail become detached from the head and disintegrate.

Animals↗