Induction of Ovulation in the Guinea-Pig

Reed, Mark; Hounslow, W. F.

doi:10.1677/joe.0.0490203

Cited by 38 publications

(27 citation statements)

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“…HCG treatment has also been reported to induce widespread atresia of growing follicles in rats (Selye et af. 1933) and guinea pigs (Reed and Hounslow 1971). In ewes the high incidence of atresia in follicles 1· 25-3·5 mm in diameter following HCG treatment would appear to be analogous to the 'wave' of follicular atresia reported in a number of species at about the time of ovulation and thus about 1 day after the LH surge (Engle 1927;Myers et af.…”

Section: Discussionmentioning

confidence: 82%

The Pattern of Follicular Growth and Atresia in the Ovine Ovary

Turnbull¹,

Braden²,

Mattner³

1977

Aust. Jnl. Of Bio. Sci.

153

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The ovaries of 21 2-year-old Merino ewes at various stages of the oestrous cycle were serially sectioned and all follicles > 0·5 mm in diameter were counted and measured. The mean number of normal follicles > 0·5 mm in diameter was 19· 9 per ewe, of which 8·7 were > 1 mm in diameter. The mean numbers of follicles > 0·5 mm in diameter in 'early', 'advanced' and 'late' stages of atresia were 4· 6, 9· 0 and 12· 3 respectively. Early atresia was rarely seen in follicles < 1 mm in diameter; the greatest incidence was in follicles of diameter 1· 5-2' 5 mm.Volumes of the granulosa, theca interna and antrum were calculated for all follicle sizes and the mitotic index of the granulosa and theca determined. Follicles were classified according to granulosa volume, each class having twice the volume of the preceding class. Estimates of the doubling time of the granulosa were made from the mitotic index and an estimate of mitotic time (0'43 h) obtained by use of colchicine on two other ewes. In all ewes, irrespective of day of oestrous cycle, the rate of growth was slow in follicles < 0·4 mm in diameter; above this size it accelerated to a maximum (doubling time 26-30 h) in follicles O· 7-2 mm in diameter. It was estimated that, on average, a follicle takes about 5 days to grow from 0·5 to 2·2mm diameter, and a further 4 days to reach 4·5 mm diameter. The number of follicles entering the rapid growth phase was estimated to be 3-4 per day. The present data do not support any particular 'wave' theory of follicular development, but indicate that follicles are growing or regressing asynchronously at any given time during the luteal stage of the oestrous cycle.At 48 h after treatment of two ewes with PMS gonadotrophin (PMSG), the number of follicles > 0·5 mm in diameter was increased, the greatest proportional increase being in those > 3·5 mm in diameter. Relatively few follicles were undergoing early atresia. At 18 h after RCG treatment (given 48 h after PMSG to two ewes) all follicles> 3·5 mm in diameter were undergoing luteinization and two-thirds of the follicles between 1 and 3·5 mm in diameter were undergoing early atresia.

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Section: Discussionmentioning

confidence: 82%

The Pattern of Follicular Growth and Atresia in the Ovine Ovary

Turnbull¹,

Braden²,

Mattner³

1977

Aust. Jnl. Of Bio. Sci.

153

View full text Add to dashboard Cite

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“…This confirms our hypothesis that only dominant follicles can be positively stained with inhibin α-subunit antiserum, and also implies that one injection of inhibin antiserum cannot increase the ovulation rate but enhances the follicular development in the late follicular phase in guinea pigs. Several studies have attempted to induce superovulation in guinea pigs with FSH or equine chorionic gonadotropin (eCG) but failed [27][28][29]. Taken together, the findings may indicate that it is very difficult to induce superovulation in guinea pigs by temporarily increasing FSH.…”

Section: Discussionmentioning

confidence: 99%

Ovarian Localization of Immunoglobulin G and Inhibin .ALPHA.-Subunit in Guinea Pigs after Passive Immunization against the Inhibin .ALPHA.-Subunit.

Shi

Mochida

Сузукі

et al. 2000

Journal of Reproduction and Development

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Abstract. The experiment was conducted to elucidate ovarian localization of immunoglobulin G (Ig G) and inhibin α-subunit and follicular development in guinea pigs after passive immunization against the inhibin α-subunit. Estrus was synchronized in laboratory guinea pigs by implanting progesterone containing-tubes. After removal of the progesterone implants, the guinea pigs were injected i.v. with 1.0 ml inhibin antiserum or normal goat serum (NGS). The results showed that Ig G mainly entered the follicular fluid of antral follicles, indicating that possibly inhibin antibodies could be a local regulator affecting follicular development in guinea pigs. The results also showed that passive immunization against inhibin increased the number of follicles and plasma concentrations of estradiol before ovulation, but did not change the plasma concentrations of follicle-stimulating hormone (FSH) or the numbers of follicles stained with inhibin antiserum. The present study first reports that the distribution of Ig G after injections of inhibin antiserum and confirms our previous hypothesis that only dominant follicles could be stained for inhibin α-subunit. The results also imply that only one injection of inhibin antiserum could not increase the ovulation rate in guinea pigs.

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“…Further, Jacquet et al [6] have confirmed the high radioresistance of the guinea pig oocyte and the consequent suitability of this species for further detailed studies in relation to genetic hazards in man. However, the guinea pig releases only 2 to 4 ova in each ovarian cycle of 16-19 days [7] and shows very little ovarian response to exogenous FSH or equine chorionic gonadotrophin (eCG) [8][9][10].…”

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confidence: 99%

Development of Embryos in Superovulated Guinea Pigs following Active Immunization against the Inhibin .ALPHA.-Subunit.

et al. 2000

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Abstract.Embryo recovery and subsequent embryonic development from guinea pigs treated with or without Inhibin vaccines were compared to determine the effect of active immunization against the inhibin a-subunit. Twenty female guinea pigs of the Hartley strain were injected 3 times either with 1 ml inhibin vaccine (recombinant ovine inhibin a-subunit in oil emulsion: 50 ,ig/ml, inhibin-immunized group), or 1 ml placebo (saline in oil emulsion; control group) at 4 week intervals. After one estrous cycle following the last injection, females were naturally mated and embryos were collected at 11:00 hr of day 6 of pregnancy (Day 1: sperm in the vaginal smear) for culture in vitro. Active immunization increased the number of corpora lutea (12.6±3.0 vs. 4.6±0.2, P<0.05), recovered embryos (9.8 ± 1.9 vs. 3.6±0.4, P < 0.01) and normal embryos (7.8 ± 1.4 vs. 3.6± 0.4, P < 0.05), although estrous cycle length was not affected (P > 0.05). During subsequent 8 day culture in vitro, most of the recovered embryos formed trophoblast outgrowth; 100% (14/14) and 88.2% (15/17) in control and immunized groups, respectively. High levels of inhibin antibody titers were sustained in the Inhibin-immunized guinea pigs at least for 5 months after the last injection while no antibody titer was detected in the control animals. These results indicate that active immunization against the inhibin a-subunit is a long-acting and efficient method to induce superovulation with normal embryonic development in the guinea pig.

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Induction of Ovulation in the Guinea-Pig

Cited by 38 publications

References 0 publications

The Pattern of Follicular Growth and Atresia in the Ovine Ovary

The Pattern of Follicular Growth and Atresia in the Ovine Ovary

Ovarian Localization of Immunoglobulin G and Inhibin .ALPHA.-Subunit in Guinea Pigs after Passive Immunization against the Inhibin .ALPHA.-Subunit.

Development of Embryos in Superovulated Guinea Pigs following Active Immunization against the Inhibin .ALPHA.-Subunit.

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