Biomedical subjects

R Yanagimachi

Publications and source records attributed to R Yanagimachi.

238 records · Page 14Linked to original sources

PubMedDate not supplied

Thiol-disulfide status and acridine orange fluorescence of mammalian sperm nuclei.

The relationship between thiol-disulfide status and acridine orange fluorescence of testicular, epididymal, and ejaculated spermatozoa in several mammalian species was investigated. Spermatozoa were fixed with acetic alcohol, stained with acridine orange, and examined with a fluorescence microscope. The majority of the nuclei of testicular spermatozoa of the hamster, mouse, and rabbit exhibited red acridine orange fluorescence. The proportion of sperm nuclei with red acridine orange fluorescence decreased as the spermatozoa descended the epididymis. Red acridine orange fluorescence was replaced by green acridine orange fluorescence. The site in the epididymis where 100% of the nuclei exhibited green fluorescence was the distal caput in the mouse, the corpus in the rabbit, and the proximal cauda in the hamster. In semen samples from men with proven fertility, normal semen parameters, or both, about 60% to 90% of the nuclei exhibited green acridine orange fluorescence. The proportion of sperm nuclei exhibiting green acridine orange fluorescence was higher in the spermatozoa pellet (containing highly motile spermatozoa) obtained by centrifugation through a Percoll gradient. From experiments using disulfide-reducing, thiol-oxidizing and thiol-detecting agents, we concluded that sperm nuclei fluoresce red when they are treated with acid while their DNA-associated protamines are poor in disulfides. Under such conditions, DNA is vulnerable to denaturation. Acridine orange binds to denatured (single-stranded) DNA as aggregates and emits red fluorescence. In contrast, when sperm nuclei are treated with acid while their DNA-associated protamines are rich in disulfides, DNA is resistant to denaturation. Acridine orange binds to native (double-stranded) DNA as a monomer and emits green fluorescence.(ABSTRACT TRUNCATED AT 250 WORDS)

Acridine Orange↗

PubMedDate not supplied

Initiation of sperm motility after mating in the rat and hamster.

Unlike those of many mammals, rat and hamster spermatozoa do not appear to be fully activated at ejaculation. Most rat spermatozoa transported en masse to the uterus approximately 2 minutes after coitus were vigorously motile on recovery soon thereafter in uterine fluid, whereas a majority, and sometimes all, were immotile in samples collected less than 2 minutes after coitus from the anterior vagina of normal females and up to 15 minutes after coitus from the anterior vagina in females with obstructed cervices. Many of these immotile rat vaginal spermatozoa began instant vigorous movement upon exposure to Tyrode's solution or uterine fluid. Hamster spermatozoa recovered from the vagina about 2 minutes after coitus were also immotile or displayed only slow, languid serpentine movements, but that motility profile remained very similar in spermatozoa taken 0.5 hours to 6 hours after coitus from the uterus, which is essentially fluid-free in the hamster. In the hamster, actively motile spermatozoa were evident only in the isthmus of the (transilluminated) oviduct. As in the rat, immotile vaginal and uterine hamster spermatozoa instantly began vigorous progressive motility in vitro on contact with Tyrode's solution or rat uterine fluid. Immotile spermatozoa from the rat and hamster cauda epididymidis immediately became highly motile in Tyrode's solution, and they developed a somewhat less rapid flagellar beat in 150 mmol/L NaCl or KCl, with or without 2 mmol/L CaCl2. In contrast, dilution with an isotonic sucrose solution containing no ions, or only 2 mmol/L CaCl2, evoked very slow and transient movement of rat and hamster epididymal sperm tails.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

Verapamil, a Ca2+ channel antagonist, accelerates the in vitro penetration of zona-free hamster eggs by human spermatozoa.

Human spermatozoa were preincubated for 3.5 h with various concentrations (0-100 mumol/l) of verapamil, a Ca2+ channel antagonist, before they were mixed with zona-free hamster eggs. Control spermatozoa penetrated only 3% of the eggs, whereas the highest penetration (40.3%) was reached after preincubation with 100 mumol/l verapamil. Thus, verapamil increases the ability of human spermatozoa to penetrate zona-free hamster eggs, possibly by an acceleration of the acrosome reaction. Although it has been established that the acrosome reaction requires the entry of extracellular Ca2+ into the spermatozoa, the Ca2+ ions do not seem to enter by means of Ca2+ channels.

Acrosome↗

PubMedDate not supplied

Spermatids from mice after cryptorchid and reversal operations can initiate normal embryo development.

We investigated fertilization and embryo development following intracytoplasmic injection of round spermatids collected from mice after cryptorchid and reversal operations. The rates of oocyte activation, blastocyst formation, and development to live offspring were compared after intracytoplasmic injection of round spermatids from intact, cryptorchid males (control) or males that had undergone the reversal operation. The incidence of normal fertilization and embryo development was about the same when the oocytes were injected with spermatids from intact cryptorchid males or males after reversal operation. The rates of the development of two-cell embryos to term were also about the same, regardless of the origin of spermatids injected. Round spermatids from both cryptorchid and previously cryptorchid testes can initiate normal embryo development when injected into mature oocytes.

Animals↗