Intrapulse temporality between pulses of a metabolite of prostaglandin F 2α and circulating concentrations of progesterone before, during, and after spontaneous luteolysis in heifers.

Pulses of the prostaglandin F(2α) (PGF) metabolite 13,14-dihydro-15-keto-PGF(2α) (PGFM) and the intrapulse concentrations of progesterone were characterized hourly during the preluteolytic, luteolytic, and postluteolytic periods in seven heifers. The common hour of the end of preluteolysis and the beginning of luteolysis was based on a progressive progesterone decrease when assessed only at the peaks of successive oscillations. The end of the luteolytic period was defined as a decrease in progesterone to 1 ng/mL.

Stimulation of the largest subordinate follicle by intrafollicular treatment with insulin-like growth factor 1 is associated with inhibition of the dominant follicle in heifers.

The effect of intrafollicular treatment of the second-largest follicle (F2) with insulin-like growth factor (IGF) 1 on the largest follicle (F1) and F2 was studied in heifers. Treatment of F2 was done when F1 reached >or=8.2 mm (expected beginning of follicle deviation; Day 0 or Hour 0).

Characteristics of pulses of 13,14-dihydro-15-keto-prostaglandin f2alpha before, during, and after spontaneous luteolysis and temporal intrapulse relationships with progesterone concentrations in cattle.

Pulses of the prostaglandin F2alpha (PGF) metabolite 13,14-dihydro-15-keto-PGF (PGFM) were compared among heifers that were in the preluteolytic, luteolytic, and postluteolytic periods (n = 7 or 8 heifers/period). Hourly blood sampling was done in 18-h sessions 15, 16, or 17 days after ovulation. Hourly sampling and statistical identification of a PGFM pulse allowed novel comparisons of PGFM pulses among the three periods.

Disruption of the periovulatory LH surge by a transient increase in circulating 17beta-estradiol at the time of ovulation in mares.

The mechanism for a reported temporal association between ovulation and a transient disruption in the periovulatory increase in LH concentrations was studied in nine mares treated with human chorionic gonadotropin when the preovulatory follicle was >/=32mm. Examinations for ovulation detection and blood collection were done at 2-h intervals and the results were retrospectively centralized to ovulation (Hour 0). Concentrations of LH began to increase (P<0.

Induced immotility during long-term storage at +5 degrees C does not prolong survival of dog spermatozoa.

This study investigated whether the immotility induced by the CLONE chilled semen extender prolongs the lifespan of dog spermatozoa stored at 5 degrees C, compared with a Tris-egg yolk-glucose (TG) extender, which maintains motility. Pooled semen was split in four aliquots, centrifuged, and the four sperm pellets mixed with TG extender; with the CLONE chilled semen (CL) extender; with TG extender mixed with an activator (TG+A(TG)); or with the CLONE extender mixed with the CLONE activator (CL+A(CL)). Samples were stored at 5 degrees C for 23 days and examined 12 times for sperm motility, plasma membrane and acrosome integrity, glucose consumption, and DNA fragmentation index (DFI).