scholarly journals The mode of ovulation in the Namaqua rock mouse, Micaelamys namaquensis

2013 ◽  
Vol 91 (11) ◽  
pp. 829-836 ◽  
Author(s):  
C.E. Relton ◽  
N.C. Bennett ◽  
K. Medger
Keyword(s):  
Reproductive Success ◽  
Social Factors ◽  
Reproductive Potential ◽  
Follicular Development ◽  
Corpora Lutea ◽  
Visual Contact ◽  
Plasma Progesterone ◽  
Specific Mode ◽  
Full Contact ◽  
Ovarian Size

The pattern of ovulation in mammals is generally considered to be either spontaneous or induced by copulation, with environmental and social factors playing a key role in determining the specific mode of ovulation that would maximize the reproductive potential of the species. This study aims to determine whether the Namaqua rock mouse (Micaelamys namaquensis (A. Smith, 1834)) is a spontaneous or induced ovulator. Females were divided into three treatments differing in the degree of contact with a male. Namely, seven control females had no contact with a male; a further seven separated females had only chemical, auditory, and visual contact with a male; whereas six females had intermittent periods of full contact with a vasectomized male. Ovarian size, follicular development, and plasma progesterone concentrations were compared between the three treatments. Penile morphology was also investigated. Corpora lutea were found in all three treatments and the penis was smooth without any ridges or spikes, indicating that M. namaquensis is a spontaneous ovulator. Interestingly, however, the presence of a male (physical as well as just visual and olfactory) positively affected ovarian size, ovulation, and plasma progesterone concentrations. This signifies that although M. namaquensis ovulates spontaneously, male contact significantly influences ovulation rate and ultimately reproductive success.

124 Ovarian follicular development and steroid secretion during oestrous cycle of Lohi sheep

2020 ◽  
Vol 32 (2) ◽  
pp. 189
Author(s):  
M. Younis ◽  
M. Irfan-ur-Rehman Khan ◽  
A. Murtaza ◽  
M. Abbas ◽  
M. Z. Tahir ◽  
...  
Keyword(s):  
Peak Plasma ◽  
Prostaglandin F2α ◽  
Follicular Development ◽  
Wave Pattern ◽  
Oestrous Cycle ◽  
Maximum Diameter ◽  
Corpora Lutea ◽  
Plasma Progesterone ◽  
Preovulatory Follicles ◽  
Wave Patterns

Pakistan has 30.9 million heads of sheep; however, little information is available on their reproductive aspects. The objective of this study was to document ovarian physiology and endocrinology of Lohi ewes during the oestrous cycle. Nine Lohi ewes, synchronized by administering single prostaglandin F2α (PGF2a; Cyclomate, Star Laboratories), were monitored for ovarian follicular dynamics using transrectal ultrasonography (7.5MHz, HS-1500, Honda) for two consecutive oestrous cycles during the breeding season (September to November 2018). Changes in plasma progesterone and oestradiol-17β concentrations of ewes (n=9) were also determined during the oestrous cycle using radioimmunoassay. The interovulatory interval of Lohi ewes averaged 17.0±0.1 days, and the duration of follicular and luteal phases was 4.6±0.2 and 11.3±0.2 days, respectively. Follicles emerged in either 3- or 4-wave patterns, but the frequency of the 3-wave pattern was higher than that of the 4-wave (87 vs. 13%, respectively; P=0.05). Following ovulation (Day 0), follicles (=3mm) in 3-wave cycles (n=14) emerged on Days 0.7, 5.2, and 10.5, whereas in 4-wave cycles (n=2) follicles emerged on Days 0.1, 4, 8.5, and 11.5. The maximum diameter of preovulatory follicles and corpora lutea (CL) were 5.4±0.3 and 10.4±0.3mm, respectively. Regardless of the wave pattern, single ovulation occurred in each cycle. The CL was first detectable on Day 4±0.1, it reached maximum diameter on Day 9±0.1, and luteolysis began on Day 12.2±0.2 of the cycle. The peak plasma oestradiol-17β concentration (42.5±2.6 pgmL−1) was observed 48h before ovulation and correlated with the diameter of the preovulatory follicle during the follicular phase (r=0.84; P<0.05). The peak plasma progesterone concentration (11.8±1.7ngmL−1) was observed on Day 9±0.1 and coincided with the diameter of CL throughout the oestrous cycle (r=0.93; P<0.05). In conclusion, the majority of oestrous cycles in Lohi ewes had a 3-wave pattern and were mono-ovulatory in nature.

STEROID-INDUCED BLOCK OF OVARIAN COMPENSATORY HYPERTROPHY IN HEMICASTRATED FEMALE RATS

1964 ◽  
Vol 29 (3) ◽  
pp. 255-NP ◽  
Author(s):  
D. L. PETERSON ◽  
R. A. EDGREN ◽  
R. C. JONES
Keyword(s):  
Follicular Development ◽  
Compensatory Hypertrophy ◽  
Left Ovary ◽  
Female Rats ◽  
Corpora Lutea ◽  
Steroidal Hormones ◽  
Ovarian Compensatory Hypertrophy ◽  
Ovarian Size ◽  
The Right ◽  
Higher Doses

SUMMARY Removal of the right ovaries of 160–180 g. rats was followed in 2 weeks by a hypertrophy of 55 % of the left ovary. This postoperative growth was prevented by the administration of various natural and synthetic steroidal hormones, which were compared at daily doses estimated to produce a 100 % block of the hypertrophy. The following steroids, together with approximate ED 100, were studied: oestrone, 17·8 μg.; oestradiol-17β, 20·4 μg.; oestriol, 95·5μg.; norethynodrel, 72·5μg.; progesterone, 3630μg.;testosterone, 436 μg.; norethisterone, 479 μg.; norbolethone, 155 μg. At doses above ED 100 the natural oestrogens and norethynodrel produced a secondary cycle of ovarian growth, whereas the Δ4-3-oxosteroids depressed ovarian size further. Hemicastrated rats had histologically normal ovaries which contained larger numbers of corpora lutea than those of the intact controls. All compounds appeared to increase follicular development at the ED 100 level; the higher doses of the oestrogens and norethynodrel stimulated excessive luteinization, whereas the Δ4-3-oxosteroids inhibited luteal development and produced large vesicular and cystic follicles.

A note on attainment of puberty of september-born early-maturing ewe lambs in relation to level of nutrition

1991 ◽  
Vol 53 (3) ◽  
pp. 407-409 ◽  
Author(s):  
F. Forcada ◽  
J. A. Abecia ◽  
L. Zarazaga
Keyword(s):  
Sexual Activity ◽  
Breeding Season ◽  
Ovulation Rate ◽  
Corpora Lutea ◽  
Plasma Progesterone ◽  
Ewe Lambs ◽  
Early Maturing ◽  
Age At Puberty

The attainment of puberty in September-born early-maturing ewe lambs was studied at Zaragoza (latitude 41° 40' N). Thirty twin Salz females were allocated to two groups receiving two nutrition levels after 3 months of age: high (500 g/day lucerne hay and 500 g/day concentrate) (H) and low (500 g/ day lucerne hay) (L). Oestrus was detected daily by aproned rams. Corpora lutea were counted after oestrus and plasma progesterone levels monitored each week.In the first breeding season (January to February) the percentage of females showing sexual activity (silent emulation or oestrus and ovulation) was higher in the H compared with the L group (67 and 20%; P < 0/05). Nonpubertal oestrus before the main breeding season was detected in 67% of animals. In the main breeding season and for H and L groups respectively, percentage of females showing silent ovulation before puberty was 67 and 33% and mean age at puberty extended to 319 (s.e. 4-8) and 314 (s.e. 3·7) days. Ovulation rate at puberty was 1·73 (s.e. 0·13) and 1·33 (s.e. 0·15) respectively (P < 0·05).

Comparison of plasma progesterone profiles in cyclic, pregnant, pseudopregnant and hysterectomized pigs between 8 and 27 days after oestrus

1988 ◽  
Vol 119 (1) ◽  
pp. 111-116 ◽  
Author(s):  
G. J. King ◽  
R. Rajamahendran
Keyword(s):  
Least Squares ◽  
Analysis Of Variance ◽  
The Other ◽  
Corpora Lutea ◽  
Plasma Progesterone ◽  
The Third ◽  
Secretory Potential ◽  
The Mean

ABSTRACT Plasma progesterone concentrations were compared in cyclic (n = 12), pregnant (n =12), oestradiol-induced pseudopregnant (n=12) and hysterectomized gilts (n=10) between days 8 and 27 after oestrus. The results were grouped into periods covering days 8–13, 14–20 and 21–27 and analysed by least-squares analysis of variance. Plasma progesterone concentrations were significantly (P<0·001) higher in hysterectomized compared with other groups between days 8 and 13. Progesterone concentrations declined rapidly after day 14 in cyclic females and gradually in the other groups. Throughout the third and fourth weeks the mean progesterone concentrations for hysterectomized animals were consistently higher than for pseudopregnant animals (P<0·05). The pregnant group means were below but not significantly different from the hysterectomized means in both of the last two periods. The greater progesterone concentrations in hysterectomized gilts indicated that secretion is high without any conceptus-produced or -mediated luteotrophin, and corpora lutea in cyclic, pregnant or pseudopregnant gilts may never reach full secretory potential. J. Endocr. (1988) 119, 111–116

scholarly journals Lifetime reproductive success in a population of female red kangaroos Macropus rufus in the sheep rangelands of western New South Wales: Environmental effects and population dynamics

2004 ◽  
Vol 26 (1) ◽  
pp. 45 ◽  
Author(s):  
AD Bilton ◽  
DB Croft
Keyword(s):  
Population Dynamics ◽  
Reproductive Success ◽  
Environmental Conditions ◽  
New South ◽  
New South Wales ◽  
Reproductive Potential ◽  
Lifetime Reproductive Success ◽  
South Wales ◽  
Macropus Rufus ◽  
Initial Starting

Female reproductive success and the recruitment of offspring to the next generation are key components of animal population dynamics. With an annual commercial harvest of between 13 and 22% of the red kangaroo (Macropus rufus) population, it is increasingly important that these processes are understood. We used data on the reproductive success of 33 free-ranging female M. rufus on Fowlers Gap station in far western New South Wales to determine the expected lifetime reproductive success (LRS) of females within an unharvested population. We also designed a model to generate predictions about female LRS incorporating empirical relationships between a mother?s reproductive success and maternal age, environmental conditions and the sex and survivorship of a previous reproductive attempt. Results from observations on female LRS (calculated from annual weaning rates) and those generated by the model predict that female M. rufus on ?Fowlers Gap? wean, on average, 3.7 young in a lifetime (ranges 0 - 11 and 0 - 20, respectively); representing only 41% of their maximum reproductive potential. Manipulation of initial starting conditions allowed the effect of varying environmental conditions on female LRS to be explored. The condition of the environment when females commence breeding does not appear to significantly affect their overall lifetime reproductive output. However, the occurrence of drought does. Females experiencing two droughts in a lifetime did not live as long and weaned fewer offspring and grandoffspring (from their daughters) than those females experiencing only one drought in a lifetime. In addition to the adverse effect of drought on the reproductive success of female M. rufus in this study, we suggest that, given the relatively high and stable population densities of M. rufus on ?Fowlers Gap?, other mechanisms (acting primarily on juvenile survival) must exist which limit population growth.

GONADAL HORMONES AND THE CONTROL OF OVULATION IN THE GUINEA-PIG

1972 ◽  
Vol 55 (3) ◽  
pp. 599-607 ◽  
Author(s):  
B. T. DONOVAN ◽  
A. N. LOCKHART
Keyword(s):  
Guinea Pig ◽  
Corpus Luteum ◽  
Acute Treatment ◽  
Gonadal Hormones ◽  
Time Of Day ◽  
Gonadal Steroids ◽  
Corpora Lutea ◽  
Plasma Progesterone ◽  
Gonadotrophin Secretion ◽  
Oestradiol Benzoate

SUMMARY The release of ovulating hormone after acute treatment with gonadal steroids, or corpus luteum removal on different days of the oestrous cycle, was studied in the guinea-pig. Injection of 25, 50 or 100 μg oestradiol or 2·5 mg progesterone on day 13 of the cycle had no effect upon gonadotrophin secretion as judged by follicular histology, but markedly altered the sizes of the corpora lutea of the previous ovulation. Treatment with oestradiol on day 14 did not elicit gonadotrophin secretion. However, administration of the same hormones to animals given 10 μg oestradiol benzoate 24 h earlier caused ovulation or follicular luteinization. Progesterone (2·5 mg) appeared least effective in stimulating gonadotrophin release; 25 μg oestradiol were more effective when given at 12.00 h than at 24.00 h but treatment with both hormones caused ovulation when given at either time of day. Luteal volumes were not affected. Removal of corpora lutea during the second half of the cycle advanced the time of expected ovulation to day 15 or earlier when the procedure was carried out on days 8 or 9, but not on days 10–13. It is concluded that 4–5 days must elapse between the fall in plasma progesterone level associated with corpus luteum regression and the release of ovulating hormone.

Development in calves and heifers after hypophysial stalk transection or hypophysectomy.

1977 ◽  
Vol 232 (5) ◽  
pp. E497
Author(s):  
L L Anderson
Keyword(s):  
Epithelial Cells ◽  
Sexual Development ◽  
Follicular Development ◽  
Seminal Vesicles ◽  
Corpora Lutea ◽  
Gonadal Function ◽  
Ovarian Weight ◽  
Thyroid Glands ◽  
Estrous Behavior ◽  
Sexually Mature

Growth was inhibited markedly in prepuberal bull and heifer calves after either hypophysial stalk transection or hypophysectomy as compared with that found in sham-operated calves or in unoperated calves. Male mounting behavior and evidence of puberal estrous behavior were lost or undetected after hypophysial stalk transection or hypophysectomy. Testes regressed, contained few spermatogonia and interstitial cells, and lacked spermatogenesis. Epithelial cells of seminal vesicles, bulbourethral glands, and prostate were cuboidal, indicating inadequate testicular androgen. Atresia of numerous ovarian follicles and reduced ovarian weight occurred in hypophysectomized heifer calves. Graafian follicles regressed after hypophysial stalk transection of sexually mature heifers, but ovaries responded to pregnant mare serum and human chorionic gonadotropin by follicular development, ovulation, and formation of multiple corpora lutea. Thyroid and adrenal gland weights decreased and adrenal cortices atrophied after hypophysectomy, but not after stalk transection. Thyroid glands contained colloid-filled follicles with flattened epithelial cells; atrophy was more extensive after hypophysectomy. Hypophysial stalk transection or hypophysectomy severely depresses growth and arrests sexual development in young calves, but in mature animals exongenous gonadotropins can sustain gonadal function.

PLASMA PROGESTERONE LEVELS IN GUINEA-PIGS ACTIVELY IMMUNIZED AGAINST PROSTAGLANDIN F2α, HYSTERECTOMIZED OR TREATED WITH INTRA-UTERINE INDOMETHACIN

1975 ◽  
Vol 67 (1) ◽  
pp. 81-88 ◽  
Author(s):  
N. L. POYSER ◽  
E. W. HORTON
Keyword(s):  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Guinea Pigs ◽  
Bovine Serum ◽  
Prostaglandin F2α ◽  
Corpora Lutea ◽  
Plasma Progesterone ◽  
Progesterone Secretion ◽  
Bovine Serum Albumin Conjugate ◽  
Prostaglandin F

SUMMARY Five guinea-pigs actively immunized against a prostaglandin F2α(PGF2α)–bovine serum albumin conjugate showed elongated oestrous cycles. During these, corpora lutea were maintained in a functional secretory state as indicated by plasma progesterone levels. The results are compatible with the view that the PGF2α antibodies neutralized the PGF2α released from the uterus and thus prevented its normal luteolytic effect. Similar patterns of progesterone secretion were observed in two hysterectomized animals and in two animals with intra-uterine implants of indomethacin.

PLASMA PROGESTERONE LEVELS IN CYCLING AND GONADOTROPHIN–PROSTAGLANDIN-TREATED HEIFERS

1976 ◽  
Vol 56 (1) ◽  
pp. 37-42 ◽  
Author(s):  
R. RAJAMAHENDRAN ◽  
P. C. LAGUË ◽  
R. D. BAKER
Keyword(s):  
Peak Level ◽  
Ovarian Activity ◽  
Corpora Lutea ◽  
Plasma Progesterone ◽  
Blood Samples ◽  
Dairy Heifers ◽  
The Mean

Progesterone levels were estimated by radioimmunoassay in blood samples obtained by venipuncture on the day of estrus and every alternate day until the onset of the next estrus in eight cycling dairy heifers. The mean level of progesterone was < 1 ng/ml during the first 2 days of the cycle, increased rapidly over the 4th–12th day period and reached a peak level value of 5.2 ± 1.1 ng/ml on day 14. Thereafter, the level declined rapidly to 2.6 ± 0.6 ng/ml on day 16 and then more gradually to 0.4 ± 0.1 ng/ml on day 21. In the second experiment, eight cycling heifers at diestrus were treated with gonadotrophin (2,000 IU PMSG or 1,000 IU PMSG + 1,000 IU HCG) followed 48 h later by 15 mg prostaglandin (PGF2α). Mid-ventral laparotomies were performed 4 days after the onset of estrus to observe ovarian activity. Progesterone levels were considerably higher in some animals and were slightly higher on the average after gonadotrophin treatments. The number of corpora lutea (CL) in these heifers ranged from 1 to 17. Progesterone levels of three heifers with 4–9 CL did not differ (P > 0.05) from those of three heifers with single CL. Two heifers each with 17 CL had peak progesterone levels of 38.4 and 27.8 ng/ml which were still high (9.6 and 26.5 ng/ml) by day 21. The remaining six heifers had low progesterone levels (< 1 ng/ml) by days 8–14, indicating premature regression of the CL. Thus, progesterone levels were not correlated with the number of CL.

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