THE CORPUS LUTEUM OF THE SHEEP: RELATIONSHIPS BETWEEN MORPHOLOGY AND FUNCTION DURING THE OESTROUS CYCLE

1966 ◽  
Vol 51 (2) ◽  
pp. 245-263 ◽  
Author(s):  
Helen Wendler Deane ◽  
Mary F. Hay ◽  
R. M. Moor ◽  
L. E. A. Rowson ◽  
R. V. Short
Keyword(s):  
Corpus Luteum ◽  
Venous Blood ◽  
Secretory Activity ◽  
Oestrous Cycle ◽  
Rapid Decline ◽  
Electron Microscopic ◽  
Functional Aspects ◽  
Luteal Tissue ◽  
And Function ◽  
Regressive Changes

ABSTRACT Certain structural and functional aspects of the regression of the corpus luteum in the sheep were studied using biochemical, histological, electron microscopic and histochemical techniques. Alterations in the size and density of mitochondria in the lutein cells on Day 12 or 13 of the oestrous cycle were the first sign of luteal regression seen. This was followed by the appearance of cytoplasmic lipid droplets on Day 13 or 14, in the large, definitive lutein cells. The rapid decline in the secretory activity of the corpus luteum on Day 15 was associated with a reduction in Δ5-3β-hydroxysteroid dehydrogenase and diaphorase activities, as well as with shrinkage of the lutein cells and pyknosis of their nuclei. Despite a general correlation between all the above regressive changes, however, there was in a few instances a lack of complete concordance between the parameters studied. It is therefore not possible to state that any one criterion gives a consistently reliable indication of the functional state of the corpus luteum. A good correlation was found between the progesterone concentration in the ovarian venous blood and that in the luteal tissue during the regression of the corpus luteum. The occurrence of some regressive changes on Day 12 may be related to the fact that this is the time when the ovine corpus luteum must be stimulated by an embryo in the uterus to survive.

Source of ovarian inhibin secretion during the oestrous cycle of the sheep

1989 ◽  
Vol 123 (2) ◽  
pp. 181-188 ◽  
Author(s):  
G. E. Mann ◽  
A. S. McNeilly ◽  
D. T. Baird
Keyword(s):  
Corpus Luteum ◽  
Luteal Phase ◽  
Venous Blood ◽  
Contralateral Side ◽  
Follicular Phase ◽  
Oestrous Cycle ◽  
Secretion Rate ◽  
Antral Follicles ◽  
Luteal Tissue

ABSTRACT The source of inhibin secretion by the ovary in the sheep at different stages of the oestrous cycle was investigated by in-vivo cannulation of the ovarian veins. Twenty-four Scottish Blackface ewes were allocated to four groups of six ewes, i.e. those operated on during the luteal phase (day 10), and those operated on during the follicular phase 24–30, 36 and 60 h following an injection of 125 μg cloprostenol on day 10 of the luteal phase. Samples of jugular and timed ovarian venous blood were collected under anaesthesia before and after enucleation of the corpus luteum. Ovaries were then removed and follicles dissected out. Following injection of cloprostenol, luteal regression occurred as indicated by a fall in the secretion of progesterone. The concentration of inhibin in jugular venous plasma and its ovarian secretion rate were similar at all stages of the follicular phase and during the luteal phase. In contrast, the secretion rate of oestradiol rose from 2·68 ±0·73 pmol/min during the luteal phase to 8·70± 2·24 pmol/min 24 h after injection of cloprostenol (P<0·05). Following enucleation of the corpus luteum the secretion rate of progesterone fell from 809 ± 270 pmol/min to 86 ± 30 pmol/min (P<0·001). There was also a smaller, artifactual fall in the secretion rate of oestradiol following enucleation of the corpus luteum, which was of similar size to a fall seen in the secretion rate of inhibin. This resulted in a significant (P<0·001) fall in the ratio of progesterone to inhibin, while the oestradiol to inhibin ratio remained unchanged. The secretion rate of inhibin from ovaries containing luteal tissue was similar to that from the contralateral side without luteal tissue (1·41±0·30 compared with 1·32±0·30 ng/min), while ovaries with large antral follicles secreted significantly (P< 0·001) more inhibin than those with no follicles ≥3 mm (2·28 ± 0·36 compared with 0·25 ±0·06 ng/min). From these results we conclude that, in the sheep, large antral follicles are responsible for most, if not all, the secretion of inhibin by the ovary at all stages of the oestrous cycle, and that the corpus luteum secretes little or no immunoactive or bioactive inhibin. Due to the fact that, unlike inhibin, the secretion rate of oestradiol rises during the follicular phase of the cycle, when the concentration of FSH is suppressed, it seems likely that oestradiol rather than inhibin is the major ovarian factor modulating the change in FSH secretion seen at this stage of the oestrous cycle. Journal of Endocrinology (1989) 123, 181–188

THE SHEEP CORPUS LUTEUM SECRETES INHIBIN

1988 ◽  
Vol 116 (3) ◽  
pp. R3-R5 ◽  
Author(s):  
C. G. Tsonis ◽  
D. T. Baird ◽  
B. K. Campbell ◽  
R. Leask ◽  
R. J. Scaramuzzi
Keyword(s):  
Corpus Luteum ◽  
Luteal Phase ◽  
Venous Blood ◽  
Follicular Phase ◽  
Oestrous Cycle ◽  
Luteal Tissue ◽  
Two Stages

ABSTRACT An experiment was performed in 20 Merino ewes in which ovarian venous blood was collected by venepuncture at surgery and at two stages of the oestrous cycle. The ovarian venous concentrations of inhibin, oestradiol-17β and progesterone were determined. The results demonstrate that during the luteal phase of the oestrous cycle the ovarian venous blood draining an ovary containing luteal tissue contains significantly more inhibin bioactivity than ovarian venous blood from an ovary not containing luteal tissue. During the follicular phase the concentration of inhibin bioactivity in ovarian venous blood was reduced compared with the luteal phase. From this data we conclude that the sheep corpus luteum secretes inhibin bioactivity into the ovarian venous blood.

SECRETION DE LA PROGESTERONE PAR LES CORPS JAUNES DE LA BREBIS APRES HYPOPHYSECTOMIE, SECTION DE LA TIGE PITUITAIRE ET HYSTERECTOMIE

1966 ◽  
Vol 52 (1) ◽  
pp. 72-90 ◽  
Author(s):  
R. Denamur ◽  
J. Martinet ◽  
R. V. Short
Keyword(s):  
Pituitary Gland ◽  
Corpus Luteum ◽  
Secretory Activity ◽  
Oestrous Cycle ◽  
Pituitary Stalk ◽  
Rapid Decline ◽  
Corpora Lutea ◽  
List Type ◽  
Normal Cycle ◽  
Progesterone Secretion

ABSTRACT The purpose of these experiments was to investigate the part played by the pituitary gland and the uterus in the control of the corpus luteum in the sheep. Six experiments were carried out, as follows: Hypophysectomy early and late in the oestrous cycle. Hypophysectomy on days 2–5 allowed the corpus luteum to continue secreting normal amounts of progesterone for up to 9 days, but thereafter the secretion declined. Hypophysectomy on days 9–10 caused the progesterone secretion to fall within 4 days. Thus it seems that the corpus luteum has a limited functional life span, and it normally requires the presence of a pituitary luteotrophin during the second half of the oestrous cycle if it is to secrete normally for 15 days. Pituitary stalk section early and late in the oestrous cycle. Regardless of the time of stalk section, the corpus luteum behaves as it would during a normal cycle. Thus pituitary stalk section does not produce the same effect as hypophysectomy, and seems to allow the severed pituitary gland to continue secreting luteotrophin. Hypophysectomy and hysterectomy carried out simultaneously early in the cycle. The results were similar to those in 1, progesterone secretion having declined significantly by days 12–15. This confirms that the declining secretory activity is due to a deficiency of pituitary luteotrophin, and not to any uterine luteolytic effect in this experiment. Pituitary stalk section and hysterectomy carried out simultaneously early in the cycle. In striking contrast to 3, some corpora lutea were still secreting progesterone normally on day 18. This shows once again that the isolated pituitary gland can continue to secrete luteotrophin. The different responses in this experiment and 2 emphasise the fact that the uterine luteolytic effect is normally dominant to the pituitary luteotrophic stimulus. Thus it would be impossible to demonstrate luteotrophic activity if the uterus were still present. Hysterectomy carried out at mid cycle, followed by hypophysectomy 20–30 days later. Whilst hysterectomy alone prolongs the secretory activity of the corpus luteum, subsequent hypophysectomy results in a rapid decline in progesterone secretion, commencing 48 hours after the operation. Thus the corpora lutea prolonged by hysterectomy, unlike those of the normal cycle, require daily pituitary luteotrophin secretion for their continued existence. Hysterectomy carried out at mid cycle, followed by pituitary stalk section 20–30 days later. Unlike 5, stalk section allows the corpora lutea to continue to secrete progesterone in large amounts for at least 15 days after the operation. This experiment, together with 2 and 4, once again emphasises that the stalk-sectioned pituitary gland can continue to secrete luteotrophin, at least for a time. These experiments therefore support the view that the cyclical corpus luteum of the sheep is under a dual control. There is a pituitary luteotrophin, whose secretion continues after stalk section, and a uterine luteolysin that is dominant to the luteotrophic stimulus, and can still function normally after pituitary stalk section. The fact that the corpus luteum of the hysterectomised animal cannot function for more than about 15 days after stalk section suggests that the luteotrophic stimulus may be complex, possibly envolving more than one hormone.

CHANGES IN THE DENSITY AND PROGESTERONE CONTENT OF LUTEAL TISSUE IN THE EGYPTIAN BUFFALO DURING THE OESTROUS CYCLE

1967 ◽  
Vol 39 (2) ◽  
pp. 163-171 ◽  
Author(s):  
A. S. EL-SHEIKH ◽  
FRANÇOIS B. SAKLA ◽  
SAFAA O. AMIN
Keyword(s):  
Corpus Luteum ◽  
Cell Volume ◽  
Distribution System ◽  
Oestrous Cycle ◽  
Luteal Cell ◽  
Corpora Lutea ◽  
Luteal Cells ◽  
Functional Changes ◽  
Parallel Increase ◽  
Luteal Tissue

SUMMARY The histological and functional changes of 31 corpora lutea of Egyptian buffaloes during the various phases of the oestrous cycle were studied. The volumes of the corpora lutea were calculated, the volume per cell, the cell volume and the volume of the intercellular spaces were estimated from transverse serial sections stained with haematoxylin and eosin, Mallory's triple stain or van Gieson's stain. The nuclear volumes were also determined and the cytoplasmic volume was calculated. The progesterone content was estimated using column absorption chromatography and a counter-current distribution system. It was concluded that the luteal cells increase both in volume and in number due to mitosis. The luteal cells decrease in volume after the 15th day after ovulation, the cells lose their distinct outlines in the regressive stage and disappear completely in the corpus albicans. There was a parallel increase in luteal cell volume and progesterone content until the 15th post-ovulatory day followed by a decrease in the regressive phase and disappearance of the hormone in the corpus albicans. A highly significant correlation (r = +0·875) was found between the progesterone content and the cytoplasmic volume. Progesterone concentration/g. luteal tissue increased from the corpus haemorrhagicum to the mature corpus luteum, decreased in the regressive corpus luteum and completely disappeared in the corpus albicans.

Effects of stress on ovarian morphology and oestrus cycles in ewes

1964 ◽  
Vol 15 (6) ◽  
pp. 937 ◽  
Author(s):  
AWH Braden ◽  
GR Moule
Keyword(s):  
Corpus Luteum ◽  
Breeding Season ◽  
Cycle Length ◽  
Acute Stress ◽  
Oestrous Cycle ◽  
Large Cavity ◽  
Severe Stress ◽  
Microscopic Appearance ◽  
Ovarian Morphology ◽  
Luteal Tissue

Observations involving over 600 sheep and extending over 4 years were made on the effect of acute stress on the oestrous cycle and ovarian morphology of ewes. In anoestrous ewes ovulation unaccompanied by oestrus was often induced by severe stress. Injections of ACTH did not induce ovulation in anoestrous ewes. During the breeding season severe stress appeared sometimes to lengthen the oestrous cycle by a few days. The presence of a large cavity in the corpus luteum (C.L.) often seemed to have been induced by stress, but the amount of luteal tissue and its microscopic appearance did not usually appear much different from solid C.L. Oxytocin injections did not affect oestrous cycles or ovarian morphology, but in some circumstances injections of ACTH or stilboestrol appeared to cause an increase in cycle length.

A METHOD TO STUDY TEMPORAL CHANGES IN ADRENAL ACTIVITY IN RELATION TO SEXUAL STATUS IN THE FEMALE LABORATORY RAT

1978 ◽  
Vol 77 (3) ◽  
pp. 283-291 ◽  
Author(s):  
J. G. PHILLIPS ◽  
W. POOLSANGUAN
Keyword(s):  
Venous Blood ◽  
Secretory Activity ◽  
Oestrous Cycle ◽  
Ovariectomized Rats ◽  
Arterial Blood ◽  
Significant Difference ◽  
Pattern Of Variation ◽  
Peripheral Arterial ◽  
High Level ◽  
Venous Plasma

There is a temporal relationship between the secretory activity of the rat adrenal gland and the stage of the oestrous cycle. In previous studies, adrenal venous blood has been sampled, but because of the stress of a lengthy operation, the gland is subjected to maximum stimulation. A new surgical approach has been developed in which samples of adrenal venous blood are taken within 3 min of contact. A competitive binding radioassay was used to determine the level of corticosterone in samples of plasma of both adrenal venous and peripheral arterial origin obtained before (3 min) and after (15 min) the onset of (presumably) ACTH-induced secretion. A reassessment of adrenal function indicated that adrenal activity peaked in pro-oestrus with higher values in the afternoon than the morning and both values were significantly higher than at any other stage in the oestrous cycle. The variations in the concentration of corticosterone in adrenal venous plasma were reflected by a similar pattern of variation in the level of corticosterone in peripheral arterial plasma. In samples of adrenal venous plasma obtained at 15 min, the level of corticosterone was approximately 25 times higher than the basal value during pro-oestrus and approximately 140 times higher than the values during the other stages of the cycle; for peripheral arterial blood the values were eight and 22–30 times higher respectively, without any significant difference when samples of either type of blood were obtained under stress. This indicates maximum stimulation by endogenous ACTH. Results obtained after treatment of ovariectomized rats with progesterone and/or oestradiol and the fact that LH, but not ACTH, plays a stimulatory role in the non-stressed metoestrous animal, suggest that the peak of adrenal activity at the time of pro-oestrus might be biphasic: in the morning it is influenced by a high level of oestrogen and a low level of progesterone; in the afternoon this balance is reversed. The effect is secondary to the surge of LH which may have a direct effect on the peak of adrenal activity at this critical period.

THE EFFECT OF HYPOPHYSIAL STALK-SECTION ON THE CORPUS LUTEUM OF THE GUINEA-PIG

1971 ◽  
Vol 50 (4) ◽  
pp. 625-635 ◽  
Author(s):  
DOREEN V. ILLINGWORTH ◽  
J. S. PERRY
Keyword(s):  
Growth Rate ◽  
Guinea Pig ◽  
Corpus Luteum ◽  
Guinea Pigs ◽  
Oestrous Cycle ◽  
Corpora Lutea ◽  
Normal Cycle ◽  
Luteal Regression ◽  
Normal Regression ◽  
And Function

SUMMARY The effects of hypophysial stalk-section on the growth and function of the corpus luteum of the non-pregnant guinea-pig have been compared with the effects of hypophysectomy (as previously described) and with the effects of prolactin administered to hypophysectomized animals. Stalk-section soon after ovulation did not impair the growth of the corpora lutea nor their ability to secrete progesterone. Stalk-section before day 9 of the oestrous cycle prevented the normal regression of the corpora lutea; they continued to grow and 3 weeks after ovulation were as large as those of pregnant animals, or of non-pregnant hysterectomized guinea-pigs. The corpora lutea regressed irregularly during the following 2 weeks. When performed on, or later than day 9, stalk-section did not prevent luteal regression at the normal time. Administration of prolactin (10 i.u./day) to hypophysectomized guinea-pigs restored the growth-rate of the corpora lutea, which reached sizes comparable to those of the normal cycle, and those of stalk-sectioned animals, by 10 days after ovulation. Our results indicate that prolactin can have substantial luteotrophic activity in the guinea-pig.

OVARIAN PROGESTERONE SECRETION DURING THE OESTROUS CYCLE, PREGNANCY AND LACTATION IN DOGS

1963 ◽  
Vol 44 (3) ◽  
pp. 461-466 ◽  
Author(s):  
G. Telegdy ◽  
E. Endröczi ◽  
K. Lissák
Keyword(s):  
Body Weight ◽  
Corpus Luteum ◽  
Human Placenta ◽  
Early Stage ◽  
Venous Blood ◽  
Placental Tissue ◽  
Oestrous Cycle ◽  
Gradual Decrease ◽  
Progesterone Secretion ◽  
Pregnancy And Lactation

ABSTRACT The concentration of progesterone in the ovarian venous blood of female dogs varied between 0.13 and 2.70 μg/h per ovary and per kg body weight, in the different phases of the oestrous cycle. There was no evidence of progesterone secretion in the absence of the corpus luteum. The highest values of progesterone secretion were detected in the early stage of pregnancy (12.9-16.2 μg/h per ovary and per kg body weight). In the course of pregnancy, a gradual decrease in progesterone secretion was found which fell below detectable amounts 48 hours after parturition. The ovarian venous blood did not contain any progesterone in the presence of a corpus luteum of lactation. There was some progesterone in the extracts of placental tissue, however, though in much smaller quantities than in the human placenta.

Oxytocin receptors in the ovine corpus luteum

1989 ◽  
Vol 121 (1) ◽  
pp. 117-123 ◽  
Author(s):  
C. Sernia ◽  
R. T. Gemmell ◽  
W. G. Thomas
Keyword(s):  
Corpus Luteum ◽  
Specific Binding ◽  
Direct Action ◽  
Oestrous Cycle ◽  
Head Size ◽  
Corpora Lutea ◽  
Fetal Head ◽  
A Value ◽  
Oxytocin Receptors ◽  
Luteal Tissue

ABSTRACT There is inconclusive evidence that oxytocin acts directly on the corpus luteum and affects steroidogenesis. Since any such action would probably be mediated by oxytocin receptors, these should be present in luteal tissue. In this study, homogenates of corpora lutea from both pregnant and non-pregnant ewes were examined for oxytocin receptors by radio-receptor assay. Specific oxytocin binding was not observed in luteal tissue during the oestrous cycle. However specific binding was found in the corpora lutea of pregnant ewes; appearing at a fetal head length of approximately 0·65 cm (about 30 days of pregnancy) and persisting to a head size of 11 cm, the largest size examined in this study. The affinity (Kd) of the receptor was calculated as 2·9 ± 0·3 nmol/l (s.e.m.; n = 9), a value similar to that obtained for the uterus. The receptor number ranged from a low of 8·7± 3·2 fmol/mg protein (n = 6) at a head size of <0·65 cm, to a maximum of 40·1 ± 6·5 fmol/mg protein (n = 25) at a head size of 2·5–3·75 cm. These values were lower than our estimate of 588 ± 39 fmol/mg protein (n = 5) for the uterus. It is concluded that a direct action of oxytocin on the corpus luteum is possible but only after the first month of pregnancy and not in the corpus luteum of the oestrous cycle. Journal of Endocrinology (1989) 121, 117–123

Transient development and function of rabbit corpora lutea after hypophysectomy

1984 ◽  
Vol 247 (6) ◽  
pp. E808-E814
Author(s):  
K. C. Yuh ◽  
C. H. Bill ◽  
P. L. Keyes
Keyword(s):  
Estrogen Receptor ◽  
Corpus Luteum ◽  
Pituitary Hormones ◽  
Corpora Lutea ◽  
Serum Progesterone ◽  
Lh Receptor ◽  
Luteal Tissue ◽  
Wet Weight ◽  
And Function

The requirement of the pituitary gland and the role of 17 beta-estradiol in the early development of the corpus luteum was investigated in rabbits hypophysectomized the day after sterile mating (day 1). Serum progesterone in hypophysectomized rabbits was normal for 2 days after hypophysectomy. Luteal tissue from hypophysectomized and sham-hypophysectomized rabbits had similar wet weight (4.0 +/- 0.4 vs. 5.3 +/- 0.2 mg/corpus luteum) and similar concentrations of available cytoplasmic estrogen receptor (1.2 +/- 0.2 vs. 1.5 +/- 0.3 fmol/micrograms DNA) and luteinizing hormone (LH) receptor (4.0 +/- 0.2 vs. 6.1 +/- 1.4 fmol/micrograms DNA) on day 4 of pseudopregnancy. Serum progesterone in hypophysectomized rabbits began to decline on day 4 and was undetectable by day 6. Estrogen receptor and luteal weight in hypophysectomized animals also declined after day 4 to low values by day 6, and serum estradiol was undetectable. However, if estradiol was administered by Silastic capsule implanted subcutaneously at the time of hypophysectomy or 3 days after hypophysectomy, serum progesterone, luteal weight, estrogen receptor, and LH receptor were maintained on day 6 of pseudopregnancy. These results indicate that after a preovulatory gonadotropin surge, the function of newly formed corpora lutea is normal for 3–4 days in the absence of pituitary hormones. However, by 4 days after ovulation, estradiol is required to sustain the structural and functional integrity of corpora lutea.

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