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Biomedical subjects

R Yanagimachi

Publications and source records attributed to R Yanagimachi.

At least 163 records · Page 9Linked to original sources
PubMed1982

[Effects of calcium and magnesium on in vitro fertilization in human].

Effects of Ca++ and Mg++ on human fertilization were investigated. For this study, in vitro fertilization assay employing the zona-free hamster eggs and the salt-stored human eggs were used. In Ca++ & Mg++-free medium, human spermatozoa could not penetrate into zona-free hamster egg. Sperm penetration occurred in Ca++-free medium containing Mg++ (1.19mM greater than or equal to) indicating that Mg++ can substitute for Ca++ although this was less effective than Ca++. In Ca++-free medium, human spermatozoa could not penetrate into zona pellucida of salt-stored human egg. These results suggest that Ca++ and Mg++ are essential for acrosome reaction of human spermatozoa. And, in Ca++ & Mg++-free medium, acrosome reacted human spermatozoa could not penetrate into zona-free hamster egg. This result indicates that Ca++ and Mg++ are essential for sperm-egg fusion, too.

Animals↗
PubMed1981

Autoantibodies from vasectomized guinea pigs inhibit fertilization in vitro.

Immunoglobulin G and Fab antibodies were isolated from the serum of vasectomized guinea pigs, and the effects of the antibodies on fertilization in vitro were investigated. These antibodies had profound inhibitory effects on (i) sperm-to-sperm adhesion, (ii) the acrosome reaction, (iii) sperm-zona binding, and (iv) sperm-ovum fusion. This finding may explain certain cases of infertility after vasovasostomy in men.

Acrosome↗
PubMed1981

Only acrosome-reacted spermatozoa can bind to and penetrate zona pellucida: a study using the guinea pig.

We have examined the behavior of guinea pig spermatozoa towards the guinea pig zona pellucida in vitro. Experiments were designed to determine whether the state of capacitation or the acrosome reaction determined the ability of the spermatozoa to attach to the zona. Freshly collected cauda epididymal spermatozoa are acrosome-intact (AI) and, by definition, uncapacitated. These cells could not attach (at least persistently) to the zona. We then sampled spermatozoa from the progressively capacitating population at various time intervals. At no point did AI spermatozoa from such samples have the ability to attach to the zona. On the other hand, acrosome-reacted (AR) spermatozoa that appeared in increasing number during this capacitation period rapidly and firmly adhered to the zona. Adhesion by AR spermatozoa prepared in several ways culminated in successful zona penetration and fertilization of the ovum. The data provide unequivocal evidence that AR guinea pig spermatozoa attach to zonae and fertilize the ova. We find no evidence that AI spermatozoa firmly attach or bind to the zona, regardless of their state of capacitation.

Acrosome↗
PubMed1981

Spermatozoa of the Atlantic bottlenosed dolphin, Tursiops truncatus.

Semen from a male dolphin in captivity was collected by electro-ejaculation and frozen to -176 degrees C. Sperm motility was excellent after thawing 10 days later. Electron microscopy showed 14-16 parallel ridges in the post-acrosomal region and two types of mitochondria in the mid-piece. The spermatozoa were capable of fusing with zona-free hamster eggs only after preincubation for 2 h, suggesting the need for sperm capacitation and acrosome reaction before fertilization in this species.

Animals↗
PubMed1980

The change in oestrogen and progesterone levels triggers adovarian propulsive movement of the hamster oviduct.

Effects of oestrogen and progesterone on oviduct movement were observed in vivo in ovariectomized hamsters. Continuous administration of oestradiol via implanted Silastic tubing did not induce co-ordinated propulsive movement of the oviduct towards the ovary, but the withdrawal of the hormone did. The most efficient adovarian propulsion was observed when the withdrawal of oestradiol was combined with progesterone administration. Progesterone alone did not stimulate this type of movement.

Animals↗
PubMed1979

Glucose effect on respiration: possible mechanism for capacitation in guinea pig spermatozoa.

Guinea pig sperm respiration was determined in minimal capacitation medium (MCM) with different energy sources. The ZO2 observed for spermatozoa suspended in media containing pyruvate and lactate was 35.7 +/- 5.9, pyruvate alone, 27.9 +/- 3.8 and D-glucose alone 3.4 +/- 1.1. When D-glucose was added to spermatozoa rapidly respiring in media containing pyruvate as the only exogenous energy source, an immediate suppression in respiration was observed. Further reduction was caused by continued addition of D-glucose. Fructose and mannose also produced a suppression in respiratory rate. However, lactose, fucose, sucrose, L-glucose, and galactose did not alter the respiratory rate. The suppression of respiration by metabolizable sugars is paralleled by a suppression of acrosome reaction in guinea pig spermatozoa. The possibility that suppression of respiration is the mechanism for retardation of capacitation and the subsequent acrosome reaction by D-glucose and other metabolizable sugars is suggested.

Animals↗
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

Retention of biologic characteristics of zona pellucida in highly concentrated salt solution: the use of salt-stored eggs for assessing the fertilizing capacity of spermatozoa.

When unfertilized hamster eggs are placed in highly concentrated solutions of neutral salts (e.g., 2 M ammonium sulfate), the egg proper, or vitellus, shrinks, creating a large perivitelline space; the zona pellucida remains unchanged in appearance under the light microscope. When these eggs are inseminated, many spermatozoa attach to and penetrate the zona. The specificity as well as several physical and chemical characteristics of the zona seem to remain unchanged during storage of the eggs in salt solutions. The properties of the human zona pellucida which allow the attachment and penetration of human spermatozoa are also retained in concentrated salt solutions. Shipment of salt-stored human eggs at ambient temperature to any part of the world is feasible and inexpensive. The present study suggests that salt-stored eggs can be used as substitutes for fresh living eggs in the preliminary assessment of fertilizing capacity of spermatozoa when collection of a large number of fresh unfertilized eggs, particularly in humans, is not practical.

Animals↗
PubMed1979

Enhanced and co-ordinated movement of the hamster oviduct during the periovulatory period.

The movement of the hamster oviduct in vivo was examined after injection of a small quantity of India ink into the lowermost region of the isthmus. An active and co-ordinated movement of both the isthmus and ampulla that caused a rapid transport of the ink to the upper ampulla (and eventually to the ovarian bursa) was observed shortly before, during and within a few hours after ovulation. During the rest of the oestrous cycle, no ink was transported to the upper ampulla despite active contractile movement by the isthmus. These observations suggest that the oviduct as a whole exhibits an efficient contractile movement suited for sperm transport only during the periovulatory period.

Animals↗
PubMed1979

Effects of human seminal plasma on fertilizing capacity of human spermatozoa.

Using zona-free hamster eggs and salt-stored human eggs for assessing the fertilizing capacity of human spermatozoa, the effects of human seminal plasma on fertilizing capacity of human spermatozoa were investigated. The persistent presence of seminal plasma prevented sperm attachment to and penetration into the zona pellucida and vitellus. A series of experiments with zona-free hamster eggs revealed that, once the spermatozoa were preincubated in a seminal plasma-free environment known to induce the acrosome reaction, the seminal plasma no longer interfered with sperm-egg fusion. The native seminal plasma appears to interfere with both the acrosome reaction and vigorous motility of the spermatozoa, and this could be the reason fertilization fails when the plasma is consistently present around the spermatozoa. The fertilization-disturbing factor or factors in the seminal plasma appear to be macromolecular substances or substances associated with macromolecules.

Animals↗
PubMed1978

Actin in mammalian sperm heads.

An actin-like substance has been detected in the postacrosomal region of mammalian spermatozoa by indirect immunofluorescence. The antigen was localized using an anti-actin antiserum from a patient with active chronic hepatitis. The actin-like contractile proteins may be important in sperm function and spermegg interactions during fertilization.

Actins↗