PubMed Health⌕ Search

Biomedical subjects

S Lake

Publications and source records attributed to S Lake.

8 recordsLinked to original sources
PubMed1979

Flow cytometry of mammalian sperm: progress in DNA and morphology measurement.

Variability in DNA content and head shape of mammalian sperm are potentially useful markers for flow cytometric monitoring of genetic damage in spermatogenic cells. The high refractive index and extreme flatness of the sperm heads produce an optical effect which interferes with DNA measurements in flow cytometers which have dye excitation and fluorescence light collection normal to the axis of flow. Orientation of sperm in flow controls this effect and results in coefficients of variation of 2.5% and 4.2%, respectively, for DNA measurements of mouse and human sperm. Alternatively, the optical effect can be used to generate shape-related information. Measurements on randomly oriented sperm from three mammalian species using a pair of fluorescence detectors indicate that large shape differences are detectable. Acriflavine-Feulgen stained sperm nuclei are significantly bleached during flow cytometric measurements at power levels routinely used in many flow cytometers. Dual beam studies of this phenomenon indicate it may be useful in detecting abnormally shaped sperm.

Animals↗
PubMed1977

Measurement of mammalian sperm deoxyribonucleic acid by flow cytometry. Problems and approaches.

Measurement of mammalian sperm deoxyribonucleic acid content is of importance in several areas of biomedical research. When measured in flow systems with orthogonal axes of illumination, flow and detection, an unexpected, distorted distribution consisting of a narrow peak with a lateral extension to the right is observed. Several lines of evidence lead to the conclusion that this effect is an optical-geometric artifact attributable to the flat shape and high index of refraction of mammalian sperm heads. This artifact disappears when an epiillumination flow system is used in which the optic axes for illumination and detection and the flow axis are all coincident. Other approaches also eliminate the artifact. The resulting coefficients of variation observed after acriflavine-Feulgen staining are 4-5%, short of the goal of 1.5% required to distinguish between human sperm bearing X and Y chromosomes and to develop a mutagen test system using mice.

Acriflavine↗
PubMed1976

Flow microfluorometric analysis of sperm DNA content: effect of cell shape on the fluorescence distribution.

The DNA content of individual sperm from populations of acriflavine-stained cells was investigated by analysis of fluorescence frequency distributions obtained with high-resolution flow-systems instruments. Sperm with spherical or cylindrical heads from three mollusk species produce narrow, symmetric fluorescence distributions. Flat sperm heads from six eutherian species produce asymmetric distributions consisting of a peak with a lateral extension to higher fluorescence values. The unexpected shape of these distributions was shown to be due to the flat geometry and high refractive index of the sperm heads in conjunction with the orthogonal axes of flow, excitation, and detection in the flow-systems instruments. The theoretical and experimeytal results indicate that the lateral extension can be eliminated either by controlling the sperm orientation with planar flow conditions or by accounting for sperm orientation by means of orientation sensing.

Acridines↗
PubMed1975

Centrifugal elutriation: separation of spermatogenic cells on the basis of sedimentation velocity.

Various types of cells from the testes of mice and hamsters were separated according to differences in sedimentation velocity by centrifugal elutriation, a counterflow centrifugation technique. Approximately 3 times 10(8) cells, prepared from six mouse testes or from one hanster testis, were separated into 11 fractions in less than two hours as compared to the 4--5 hours required for sedimentation at unit gravity ("Staput"). Fractions enriched in elongated spermatids and spermatozoa (100%), stages 1--8 spermatids (69%) and pachytene spermatocytes (58%) were obtained from mouse testis dispersions. Similarly enriched fractions were obtained from hamster cells. A single fraction enriched in stages 1--8 spermatids (mouse) was prepared in less than 30 minutes. As many as 2 times 10(9) cells were separated in a single procedure. Spermatogenic cells exhibited no evidence of structural damage with trypan blud and phase microscopy, and recovery was essentially 100%. Centrifugal elutriation had no effect on sperm motility or on the plating efficiency of CHO cells.

Animals↗