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Biomedical subjects

M Coryn

Publications and source records attributed to M Coryn.

15 recordsLinked to original sources
PubMed1990

Plasma estradiol-17 beta concentrations in the cow during induced estrus and after injection of estradiol-17 beta benzoate and estradiol-17 beta cypionate--a preliminary study.

Plasma estradiol-17 beta concentrations were investigated in cows during induced estrus and after an intramuscular injection of 10 mg of estradiol-17 beta benzoate and estradiol-17 beta cypionate to determine a withdrawal period for both preparations. After the estradiol-17 beta benzoate injection, the plasma estradiol-17 beta concentration was higher than the physiological maximum of 24 pg/ml obtained during induced estrus for a period of 114 +/- 10 h (mean +/- SEM). For estradiol-17 beta cypionate the corresponding value was 170 +/- 17 h (mean +/- SEM). A withdrawal period of 7 days for the benzoate ester and of 10 days for estradiol-17 beta cypionate is therefore proposed. These results were confirmed by biopsies taken at the injection site 8 and 15 days after the injection of estradiol-17 beta benzoate and estradiol-17 beta cypionate, respectively. In these biopsies no residues of estradiol-17 beta nor of its esters could be detected.

Animals↗
PubMed1987

Clinical and endocrine aspects of the oestrous cycle in donkeys (Equus asinus).

Oestrous behaviour and occurrence of ovulation was studied in 13 jenny asses (3-18 years) during a 15-month period. Teasing was performed daily and follicular growth, ovulation and changes of the genitalia were checked every other day by rectal palpation during dioestrus or the anovulatory season or daily during oestrus and when a follicle greater than or equal to 3 cm in diameter was present. Plasma oestrogens and progesterone levels were measured by radioimmunoassay (RIA). Of the 13 jennies, 6 showed a typical seasonal ovarian activity, 1 stopped cycling only at the end of the experiment, 2 ovulated regularly and 4 did not cycle. Mean (+/- s.d.) length of the anovulatory season in the 6 jennies with seasonal cyclic ovarian activity was 166.3 +/- 63.2 days (74-263 days). Irregular oestrous periods were detected during the anovulatory season of these jennies. Irregular signs of oestrus and follicular growth were detected in the 4 jennies which remained acyclic during the whole experiment. Mean (+/- s.d.) length of the ovulatory season was 197.8 +/- 63.4 days (102-291 days). Overall mean +/- s.d. lengths for the oestrous cycle and dioestrous and oestrous periods were 25.9 +/- 2.7 (n = 74), 18.2 +/- 2.3 (n = 70) and 7.9 +/- 2.5 (n = 79) days. Ovulatory oestrous periods tended to be longer at the start and end of the season than during the summer months. Dioestrous length was not affected by season.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1979

The mature mid-cycle follicle in the mare.

Oestrogen and progesterone concentrations in blood and follicular fluid and blood levels of LH were determined in 426 mares at different stages of the oestrous cycle. Mature follicles occur at all stages of the cycle; they ovulate readily in early metoestrus, occasionally in late metoestrus and very rarely in dioestrus. Maturation of a mid-cycle follicle is associated with intermediate levels of LH, which are less than those found during oestrus. This lower level of LH together with a high level of progesterone are probably responsible for the failure of ovulation and regression of most of the mid-cycle mature follicles found in the mare.

Animals↗
PubMed1978

Embryo transfer in cattle: an evaluation of the current situation.

A technique for the transcervical recovery of ova in cattle is described. The donors recipient pool consisted of 122 cows of different ages and 4 different breeds. Of these 102 cows were superovulated. For recovery of ova an apparatus consisting of a metal catheter glued to the inside of a 3-way Foley catheter was used. The technique used for embryo transfer was basically the same as for collecting the embryos. The 102 donors yielded at slaughter a total of 956 corpora lutea i.e. an average of 9,4 per cow. Of the ova released 294 or 30% were recovered on transcervical flushing of the uterus. 40% of the inovulated cows conceived. The future development of inovulation in cattle is discussed on the basis of the results recorded and on those previously documented.

Animals↗
PubMed1978

Clinical and endocrinological aspects of induced parturition in multiparous sows.

Intramuscular administration of PGF2alpha or its analogue ICI 80996 at 110--112 days of gestation results in grouped parturition. The decrease of progesterone levels is interrupted by a temporary increase. During expulsion rather high values are obtained compared to the control group. Unconjugated oestrogens increase, reaching maximum values just before expulsion.

Animals↗
PubMed1975

The use of prostaglandin F2alpha in controlling the oestrous cycle of the mare and steroid changes in the peripheral blood.

Prostaglandin F2alpha (PGF2alpha), administered by untrauterine infusion and intramuscular injection, was used to induce oestrus and ovulation in non-cyclic mares. A satisfactory response rate (80% or more) was obtained and the dose (2-5--7-5 mg) and the time taken for ovulation to occur (up to 9 days) was the same irrespective of the route of administration. Only about one-half of the mares conceived to mating at the induced oestrus but the low conception rate could be attributed to the infertile condition of the mares. Plasma progesterone remained at basal levels after PGF2alpha and oestrogen levels were inconsistent. The use of PGF2alpha in the treatment of severe endometritis was successful in one mare.

Animals↗