Alternating current resistance and capacity measurements have been made from 1.08 10(3) to 2.32 10(6) cycles per second on suspensions of unfertilized, fertilized, and swollen unfertilized eggs of the echinoderm Hipponoë esculenta. A simple method has been developed for measuring the volume concentration of eggs in a suspension. The membrane of the unfertilized egg is practically non-conducting...

BACKGROUND In the majority of animals, the centrosome-the microtubule-organizing center of the cell-is assembled from components of both the sperm and the egg. How the males of the insect order Hymenoptera acquire centrosomes is a mystery, as they originate from virgin birth. RESULTS To address this issue, we observed centrosome, spindle and nuclear behavior in real time during early developm...

In vivo embryogenesis, embryo migration, and survival were studied in the domestic cat. Queens were naturally mated (three times daily) on the second and third days of behavioral estrus and, if ovulation occurred, ovariohysterectomized at 64 (n = 8), 76 (n = 11), 100 (n = 8), 124 (n = 7), 148 (n = 6), and 480 h (n = 8) after first copulation. Of 52 cats mated, 48 (92.3%) ovulated (as evidenced ...

In vivo embryogenesis, embryo migration, and survival were studied in the domestic cat. Queens were naturally mated (three times daily) on the second and third days of behavioral estrus and, if ovulation occurred, ovariohysterectomized at 64 (n = 8), 76 (n = 11), 100 (n = 8), 124 (n = 7), 148 (n = 6), and 480 h (n = 8) after first copulation. Of 52 cats mated, 48 (92.3%) ovulated (as evidenced ...

introduction: cryopreservation of single human spermatozoa is a new technique designed to improve the management of male infertility, it was first introduced in 1997 and was reported by others latter. the aim of this research was to evaluate the efficiency of this method in preserving either ejaculated or surgically retrieved spermatozoae. materials and methods: spermatozoae were obtained from ...