INDUCTION OF OVULATION IN THE GUINEA-PIG

1971 ◽  
Vol 49 (2) ◽  
pp. 203-211 ◽  
Author(s):  
MAY REED ◽  
W. F. HOUNSLOW
Keyword(s):  
Luteinizing Hormone ◽  
Guinea Pig ◽  
Pituitary Gland ◽  
Guinea Pigs ◽  
Anterior Pituitary ◽  
Single Injection ◽  
Follicle Stimulating Hormone ◽  
Untreated Animal ◽  
Basal Secretion ◽  
Induction Of Ovulation

SUMMARY Ovulation has been induced in the cyclic guinea-pig at a time when the ovaries contain mature follicles, by a single injection of purified luteinizing hormone (LH), follicle-stimulating hormone or guinea-pig gonadotrophins from homogenates of female guinea-pig anterior pituitaries. An injection of any one of the substances given too early only caused follicular luteinization and the ova were retained, even with increased dosage. A single injection of LH in mid-dioestrus caused 'LH effects' on the follicles (destruction of the growing follicles), giving a histological picture similar to that which obtains at the time of ovulation in the untreated animal. Homogenates of anterior pituitaries taken from donor guinea-pigs 1–2 days before ovulation was due (but not at any other time in the cycle) when injected into recipients at middioestrus had similar effects on the follicles. Donor anterior pituitaries taken from guinea-pigs in which ovulation had been inhibited by daily injections of progesterone, caused ovulation in recipients with mature ovarian follicles or 'LH effects' in those in mid-dioestrus. It is suggested that in the guinea-pig there is a basal secretion of gonadotrophins during most of the cycle. A day or two before ovulation occurs and when the ovaries already contain ripe follicles, there is a marked increase in the synthesis of LH which is then released from the anterior pituitary gland and rupture of the follicles occurs.

THE ONSET OF FIRST OESTRUS IN THE GUINEA-PIG AND THE EFFECTS OF GONADOTROPHINS AND OESTRADIOL IN THE IMMATURE ANIMAL

1971 ◽  
Vol 50 (2) ◽  
pp. 329-337 ◽  
Author(s):  
P. G. MILLS ◽  
MAY REED
Keyword(s):  
Guinea Pig ◽  
Anterior Pituitary ◽  
Single Injection ◽  
Follicle Stimulating Hormone ◽  
Vaginal Opening ◽  
Hormonal Activity ◽  
Immature Female ◽  
Hormone Injection ◽  
Premature Ovulation ◽  
Pituitary Homogenate

SUMMARY The immature female guinea-pig approaching first oestrus and ovulation has been studied. A clear relationship between the rate of growth of the animal and the age at puberty has been found. The 'crucial period', a time just before first oestrus, when external signs of endogenous hormonal activity give an indication of the presence of ripening follicles in the ovary, has been defined. At this time premature ovulation can be regularly induced by a single injection of gonadotrophin (guinea-pig anterior pituitary homogenate, purified luteinizing hormone or follicle-stimulating hormone). Injection of oestrogen advanced vaginal opening but, in contrast to the rat, did not cause premature ovulation.

Effect of Starvation on Pituitary and Serum Follicle-Stimulating Hormone and Luteinizing Hormone Following Ovariectomy in the Rat

1972 ◽  
Vol 50 (8) ◽  
pp. 768-773 ◽  
Author(s):  
E. A. Ibrahim ◽  
B. E. Howland
Keyword(s):  
Luteinizing Hormone ◽  
Pituitary Gland ◽  
Follicle Stimulating Hormone ◽  
Female Rats ◽  
Intact Female ◽  
Pituitary Glands ◽  
Ad Libitum ◽  
Stimulating Hormone

The concentration of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in serum and pituitary glands was studied in intact female rats and rats that were ovariectomized on day 0 of the experiment and then starved or fed for 2, 4, 7, or 9 days. Ovariectomy resulted in enhanced rates of synthesis and release of FSH and LH as indicated by the significant (P < 0.01) rises in the concentration of both hormones in the pituitary gland and serum.Starvation resulted in a decrease in body and pituitary weight. The concentration of FSH and LH in pituitary glands of starved rats was higher (P < 0.05) than that in fed rats on days 7 and 9. The concentration of FSH and LH in serum of starved rats was increased after ovariectomy but the levels on days 7 and 9 were lower than those of fed rats.These results suggest that the synthesis of FSH and LH was enhanced in both starved and fed rats following ovariectomy while the rate of release of both hormones was decreased at 7 and 9 days of starvation in comparison with rats fed ad libitum.

Infertility

2013 ◽  
pp. 551-566
Author(s):  
John Reynard ◽  
Simon Brewster ◽  
Suzanne Biers
Keyword(s):  
Luteinizing Hormone ◽  
Male Infertility ◽  
Anterior Pituitary ◽  
Treatment Options ◽  
Follicle Stimulating Hormone ◽  
Reproductive Physiology ◽  
Seminiferous Tubules ◽  
Luteinizing Hormone Releasing Hormone ◽  
Releasing Hormone ◽  
Gonadotrophin Releasing Hormone

Male reproductive physiology 552 Aetiology and evaluation of male infertility 554 Investigation of male infertility 556 Oligozoospermia and azoospermia 560 Varicocele 562 Treatment options for male infertility 564 The hypothalamus secretes luteinizing hormone-releasing hormone (LHRH), also known as gonadotrophin-releasing hormone (GnRH). This causes the pulsatile release of anterior pituitary gonadotrophins called follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which act on the testis. FSH stimulates the seminiferous tubules to secrete inhibin and produce sperm; LH acts on Leydig cells to produce testosterone (...

INDUCTION OF OVULATION IN SHEEP BY INTRA-ADENOHYPOPHYSIAL INFUSION OF HYPOTHALAMIC EXTRACTS

1968 ◽  
Vol 42 (3) ◽  
pp. 383-389 ◽  
Author(s):  
E. DOMÁNSKI ◽  
K. KOCHMAN
Keyword(s):  
Luteinizing Hormone ◽  
Pituitary Gland ◽  
Median Eminence ◽  
Strong Evidence ◽  
Late Phase ◽  
Follicle Stimulating Hormone ◽  
Ovarian Response ◽  
Corpora Lutea ◽  
Seasonal Differences ◽  
Releasing Factors

SUMMARY The follicle-stimulating hormone releasing factor (FSH-RF) and luteinizing hormone-releasing factor (LH-RF) activity in sheep hypothalamic extracts and their action on the release of gonadotrophins from the pituitary gland has been studied by the infusion of extracts of the stalk and median eminence (SME) directly into the adenohypophysis of ewes in various phases of their non-cycling quiescent sexual period. The intra-adenohypophysial infusion of hypothalamic extracts during mid-anoestrus elicited no ovarian response, while similar infusion of the same extracts in the late phase of anoestrus, e.g. in the last 2–4 weeks before the onset of the breeding season, induced the growth and rupture of ovarian follicles as well as development of corpora lutea. This ovulatory response provides indirect but strong evidence for the ability of hypothalamic extracts to release gonadotrophins (FSH as well as LH) from the pituitary gland. The seasonal differences in the response of ewes to intra-adenohypophysial infusions of hypothalamic extracts suggest that the sensitivity of the adenohypophysis to the hypothalamic releasing factors varies during the year.

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