Response of anestrous ewes to the ram effect after follicular wave synchronization with a single dose 
of estradiol-17?

The objective of the current study was to examine follicular dynamics in goats induced to ovulate by using the male effect with or without progesterone pretreatment. Ten Murciano–Granadina goats were treated with a single dose of 25 mg of progesterone in olive oil on the day of male effect induction (Day 0), whereas ten does remained untreated. Changes in the ovarian follicular population and onset of oestrous behaviour were checked daily from Day 0 to the day on which ovulation was detected by ultrasonography. All of the treated goats and only 20% of control goats (P < 0.001) showed oestrous behaviour between 72 and 96 h after the introduction of bucks. Differences in follicle growth were found between the groups. The control goats exhibiting oestrous behaviour during the first 4 days of ovarian screening and all of the goats treated with progesterone had their preovulatory follicles in growing phase. However, the largest follicles in control does not showing oestrus in these first 4 days were in regressing phase, being necessary for the emergence of new preovulatory follicles from a new follicular wave between Days 6 and 7, for exhibition of oestrous behaviour and subsequent ovulation. In conclusion, the appearance of short luteal phases and delayed ovulation in goats treated with the male effect during seasonal anoestrous depends on the stage of follicle development at the time of buck introduction. A single injection of progesterone stimulates the emergence of a new follicular wave, able to grow and give adequate ovulation after induction of the male effect.

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227 EFFECTS OF A SINGLE DOSE OF A NONSTEROIDAL AROMATASE INHIBITOR ON OVARIAN FUNCTION IN CATTLE

Reproduction Fertility and Development ◽

10.1071/rdv22n1ab227 ◽

2010 ◽

Vol 22 (1) ◽

pp. 271 ◽

Cited By ~ 1

Author(s):

M. J. Yapura ◽

R. J. Mapletoft ◽

J. Singh ◽

R. A. Pierson ◽

G. P. Adams

Keyword(s):

Single Dose ◽

Aromatase Inhibitor ◽

Ovarian Function ◽

T Test ◽

The Body ◽

Farm Animals ◽

Saline Control ◽

Dominant Follicle ◽

Follicular Wave ◽

Treatment Research

Many countries have banned the use of estrogenic products in farm animals. Nonsteroidal aromatase inhibitors prevent the body from producing its own estrogen. The effects on the ovary are thought to be a result of suppression of estrogen-producing follicles and a rebound in endogenous levels of FSH through the removal of the negative feedback effect of estradiol. An experiment was designed to determine the effects of a nonsteroidal aromatase inhibitor, letrozole, on ovarian function in cattle. The specific objective was to test the hypothesis that letrozole will arrest growth of the dominant follicle, resulting in emergence of a new follicular wave at a predictable interval post-treatment. Beef heifers were assigned randomly to 4 groups and given phosphate-buffered saline [control; (n = 10)] or letrozole at a dose of 500 (n = 9), 250 (n = 10), or 125 (n = 10) μgkg-1 i.v. 4 days after follicular ablation (≈ 2.5 days after wave emergence, at the time dominant follicle selection is manifest). Blood samples were collected and ovarian structures were monitored daily by transrectal ultrasonography. Analysis of variance for repeated measures, one-way ANOVA, paired t-test, and 2-sample t-test were applied to the analysis of the data. The diameter profile of the dominant follicle was larger in heifers treated with letrozole than in control heifers (P < 0.05). The intervals from treatment to new wave emergence and from treatment to onset of regression of the extant dominant follicle were longer (P < 0.05) in heifers treated with letrozole than in controls, although variances in the intervals were not different. A small but significant reduction in circulating estradiol concentration was observed, and plasma LH concentrations were higher (P < 0.05) in letrozole-treated heifers than in controls. Lower plasma concentrations of FSH in letrozole-treated heifers than in controls (P < 0.03) was interpreted as an indirect effect resulting from prolonged follicular dominance. In summary, a single dose of letrozole did not induce regression of the extant dominant follicle, nor did it directly affect FSH release. Conversely, letrozole extended the lifespan of the dominant follicle, in association with increased endogenous levels of LH, thereby delaying the next FSH surge and subsequent follicular wave emergence. Results suggest that letrozole has potential as a nonsteroidal method of controlling ovarian function in cattle but further studies are needed to clarify dosage and timing of treatment. Research supported by the Natural Sciences and Engineering Research Council of Canada and Bioniche Life Science Inc.

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The Response of Testes Cells to Low Level, Single dose Helium Particle Irradiation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100053929 ◽

1982 ◽

Vol 40 ◽

pp. 252-253

Author(s):

D.E. Philpott ◽

W. Sapp ◽

C. Williams ◽

J. Stevenson ◽

S. Black ◽

...

Keyword(s):

Stem Cell ◽

Single Dose ◽

B Cell ◽

Cell Survival ◽

Spermatogonial Stem Cell ◽

Low Doses ◽

Particle Irradiation ◽

Stem Cell Survival ◽

Irradiation Injury ◽

Radio Sensitivity

Spermatogonial stem-cell survival after irradiation injury has been studied in rodents by histological counts of surviving cells. Many studies, including previous work from our laboratory, show that the spermatogonial population demonstrates a heterogeneous response to irradiation. The spermatogonia increase in radio-sensitivity as differentiation proceeds through the sequence As - Apr - A1 - A2 - A3 - A4 - In - B. The stem (As) cell is the most resistant and the B cell is the most sensitive. The purpose of this work is to investigate the response of spermatogonial cell to low doses (less than 10 0 rads) of helium particle irradiation.

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Gastric Ulcers Produced by Cisplatin

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100099337 ◽

1981 ◽

Vol 39 ◽

pp. 582-583

Author(s):

S.K. Aggarwal ◽

J. San Antonio

Keyword(s):

Electron Microscopy ◽

Single Dose ◽

Side Effects ◽

Antitumor Agent ◽

Gastric Ulcers ◽

Enzyme Cytochemistry ◽

Intestinal Toxicity ◽

Ovarian Cancers ◽

Inner Surface

Cisplatin (cis-dichlorodiammineplatinum(II)) a potent antitumor agent is now available for the treatment of testicular and ovarian cancers. It is however, not free from its serious side effects including nephrotoxicity, gastro intestinal toxicity, myelosuppression, and ototoxicity. Here we now report that the drug produces peculiar bloating of the stomach in rats and induces acute ulceration.Wistar-derived rats weighing 200-250 g were administered cisplatin(9 mg/kg) ip as a single dose in 0.15 M NaCl. After 3 days the animals were sacrificed by decapitation. The stomachs were removed, the contents analyzed for pepsin and acidity. The inner surface was examined with a dissecting microscope after a moderate stretching for ulcers. Affected areas were fixed and processed for routine electron microscopy and enzyme cytochemistry.The drug treated animals kept on food and water consistently showed bloating and lesions (Fig. 1) with a frequency of 6-70 ulcers in the rumen section of the stomachs.

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