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M A Driancourt

Publications and source records attributed to M A Driancourt.

66 records · Page 4Linked to original sources
PubMed1984

Preovulatory follicular events in sheep.

To investigate the number, size and fate of the follicles greater than 2 mm in diameter involved in the differentiation of the preovulatory follicle in-vivo monitoring of growth and regression of individual follicles was performed at different times after a PG-induced follicular phase. In Exp. 1, the 3 largest follicles of each ovary were labelled with ink in the peripheral stroma at 0, 4, 8, 12, 24 or 48 h after a PG injection. At a second laparotomy, it was assessed which follicles had ovulated. In Exp. 2, a similar procedure was applied in 12 ewes which underwent repeated laparotomies at 6, 30 and 54 h after PG and after ovulation. At all times, there was a huge variability in the size at the time of ink labelling of the follicles that finally ovulated ('ovulatory' follicles). A single measurement of follicle size is therefore a poor prediction of the ovulatory follicles. However, a significant reduction in the proportion of non-ovulatory follicles within the size range of ovulatory follicles occurred at 12-24 h after PG, together with a change in follicle hierarchy at 8-24 h after PG. The results of repeated laparotomies showed that only 60% of follicles greater than 2 mm at 6 h after PG had grown by 30 h. Selection occurred between 30 and 54 h after PG as indicated by a significant drop in the number of growing follicles to a level at 54 h that equalled the ovulation rate. The growth rate of the ovulatory follicles was 1.4 and 0.4 mm per day between 6 and 30 h and 30 and 54 h after PG respectively. The shrinkage rate of non-ovulatory follicles was 1.6 mm/day.

Animals↗
PubMed1983

Seasonal effects on ovarian follicular development in pony mares.

To define ovarian follicular kinetics in the equine ovary during anestrus and the breeding season, the follicular population of pony mares was investigated at mid-anestrus and at the beginning and end of the breeding season. There was a clear effect of season on the exit of reserve (primordial and initiated) follicles since at the beginning of the breeding season we noticed a higher mitotic index for the smaller preantral follicles, leading to an accumulation of small and medium antral follicles. In contrast, the ovaries sampled during anestrus or at the end of the breeding season were very similar; only preovulatory development was lacking in anestrous ovaries. However, atresia was unaffected by season.

Anestrus↗
PubMed1983

Hormonal levels after ovarian X-irradiation of ewes.

This paper reports the effects of X-irradiation on ovulation rate, cyclicity and progesterone and FSH levels in Ile-de-France ewes (4 control and 16 irradiated) after they were treated during the breeding season. The doses used (800 and 2 400 R) destroyed 50% of all size classes of the follicular population. Ovulation occurred in 87% of the treated ewes (ovulation rate = 1) when they were irradiated 24 h after luteolysis; 78% of the corpora lutea resulting from these ovulations were normal as to length and progesterone production. FSH in treated ewes started to increase 20 h after treatment and remained higher than in the controls until ovulation time. Later, while these levels were similar between groups on the day of ovulation, high ovulatory levels persisted in irradiated ewes. In the next cycles, the length of the follicular phases, ovulation rate and progesterone and FSH levels were similar between groups.

Animals↗
PubMed1982

Effect of the stage of the oestrous cycle on the follicular population in pony mares.

In the middle of the breeding season, 16 pony mares (n = 4 per day) were slaughtered on four different days (days 6, 14, 17 and the preovulatory day) of the oestrous cycle, day 0 being the day of the last ovulation. All the ovaries were examined histologically; the number, size and atresia (defined by granulosa cell pyknosis) of all follicles larger than 1 mm in diameter were studied, using a Kryotome-video recorder-TV system. Follicular distribution of all the sizes studied (1-5 mm, 5-10 mm, greater than 10 mm in diameter) was very similar in the right and left ovaries. However, compared to the other ovary, the ovary with a luteal structure had fewer (P less than 0.05) healthy follicles larger than 10 mm. All follicles larger than 10 mm in diameter at day 6 were atretic. At day 14, a group of normal follicles larger than 10 mm was found in all the animals, and number of follicles larger than 10 mm was significantly increased (P less than 0.01). The largest normal follicle has increased in size at day 17 compared to day 14. However, a significant increase in the number of follicles undergoing early atresia was observed (P less than 0.05). Except for the large preovulatory follicle, all the follicles larger than 10 mm were atretic just before ovulation. There was a relationship between the follicular population and the duration of the follicular phase; the number of normal follicles 1-10 mm in diameter and the duration of the follicular phase were highly correlated (R = -0.56; P less than 0.02).

Animals↗
PubMed1982

Short and long-term effects of X-irradiation on ovarian follicular populations in the ewe.

The effects of X-irradiation on the total number of follicles larger than 50 microns in diameter have been studied 10 and 42 days after treatment (short vs long-term animals). A comparison of short-term and control animals showed a sharp reduction in the healthy-follicle population; only 50 p. 100 of the preantral follicles and 40 p. 100 of the antral follicles survived irradiation. The mitotic index of the antral follicles was also reduced and the between-ovary equilibrium per animal was altered. When compared to short-term animals, long-term ewes did not show follicular compensation similar to that seen after hemicastration. Furthermore, the mitotic index did not increase over the control values. Cyclic ovarian activity was maintained despite this.

Animals↗
PubMed1982

Ovarian follicular populations in pony and saddle-type mares.

Five pony and 5 saddle-type mares were used to compare total ovarian follicular populations between breeds. The animals were hemi-ovariectomized at the preovulatory stage during the breeding season and the ovary bearing the large preovulatory follicle was studied using histological techniques. Pony and saddle-type mares did not differ as to mean number of primordial follicles, mean number of growing follicles, the variability of these numbers and follicular distribution into various size classes. No difference was detected either in the initiation processes of follicular growth, oocyte growth, granulosa cell multiplication and follicular atresia. However, significant differences were found in the pattern of antral formation (P less than 0.01). The present data suggest that pony mares are a valuable tool for the study of follicular populations in equines. The main features of the equine ovary are the small number of follicles (35 950 primordial and 100 growing follicles) and the high individual variability of this number (5 600 to 75 000 primordial and 20 to 300 growing follicles).

Animals↗
PubMed1982

Seasonal and individual effects on ovarian and endocrine responses of mares to a synchronization treatment with progestagen-impregnated vaginal sponges.

The 8 saddle-type mares were treated with progestagen-impregnated vaginal sponges for 8 days and prostaglandin on the day of sponge removal. The treatment was given at random days of the cycle in April, May, July and September. Sponge insertion induced a sharp decrease in LH levels; at sponge removal, there was an immediate increase in LH and a large FSH rebound. Ovulation was synchronized 11 +/- 2 . 8 days (s.d.) after the end of treatment. In April the interval from sponge removal to ovulation was longer (14 days compared with 10 . 1, 10 . 7 and 10 . 2 days), the basal and peak LH levels lower, and follicular growth more delayed than in the 3 other months. In July, there was a prolonged oestrogen preovulatory rise and reduced FSH levels. Numerous individual differences were shown, but none was significantly linked to the interval from sponge removal to ovulation. Within the 3 months when response was unaffected by season, the interval from end of treatment to ovulation was correlated with progesterone (r = 0 . 45 and r = 0 . 50) and FSH (r = -0 . 48 and r = -0 . 49) levels at Days 5 . 6 and 7 . 8 after sponge insertion. This means that in treated mares that have an active corpus luteum at the end of treatment there will be low FSH levels at this time and ovulation will be late. A good prediction of the ovulation time after such a synchronization treatment must therefore take into account season, animal and time of treatment in the oestrous cycle.

Animals↗
PubMed1981

A rapid technique for the histological examination of large ovarian follicles.

A rapid technique for counting and classifying large ovarian follicles of domestic animals is described. Using a cryostat, 250-micrograms thick sections were cut from the frozen ovary; an image of the surface of each ovarian section was recorded on videotape. By replaying the videotape, the largest profile of each follicle larger than 1 mm in diameter was readily identified and measured. The presence or absence of atresia was determined by applying standard histological methods to fragments of individual follicles taken from the frozen sections. The results obtained are similar to those found using previous methods and demand only one-quarter of the time.

Animals↗
PubMedDate not supplied

Control of oocyte growth and maturation by follicular cells and molecules present in follicular fluid. A review.

The aim of this review is to summarize the interactions between the oocyte and its surrounding granulosa cells which are involved in the control of oocyte growth or apoptosis as well as those playing a key role in the ability of the oocyte to undergo nuclear (resumption as meiosis to reach the MII stage) or cytoplasmic maturation (ability to fertilize and develop to the blastocyst stage). The respective roles of the oocyte and of the granulosa cells in controlling the initiation of growth are poorly understood. During the preantral follicular stage when most oocyte growth is achieved, a local regulation appears to be in operation involving growth factors such as fibroblast growth factor (FGF) or epidermal growth factor/transforming growth factor alpha (EGF/TGF alpha), together with two proteins (c-kit present on the oocyte's membrane and its ligand KL produced by granulosa cells). In-situ techniques used to detect apoptosis demonstrate apoptotic oocytes in the reserves of primordial follicles but seldom within preantral follicles (because it is too fast?). Proteins involved in cell death (bax) or cell survival (bcl2) are present in oocytes as well as compounds (TNF alpha, Fas) involved in the initiation of apoptosis. However, the molecular and cellular mechanisms triggering oocyte apoptosis are not fully clarified. Three approaches have been used to identify compounds which are relevant to the oocyte's nuclear or cytoplasmic maturation. a) Correlation between amounts of specific compounds in follicular fluid or within follicle cells and the oocyte's ability to mature. b) Analysis of the consequences of pharmacological disruption of mechanisms such as steroidogenesis on oocyte maturation. c) Analysis of the consequences of addition of graded amounts of specific compounds on oocyte maturation in defined media. Factors playing a key role in stimulating nuclear maturation appear to be epidermal growth factor (EGF) and the inhibin (cattle)/activin (rodents) family, while testosterone has an inhibitory effect. Cytoplasmic maturation of the oocyte appears to be stimulated by oestradiol, EGF and inhibin.

Animals↗
PubMedDate not supplied

[In vitro folliculogenesis: a woman is not a mouse!].

The informations obtained using in vitro folliculogenesis in rodents have shown that ovulation of preantral follicles or granulosa-cumulus complexes can be obtained after a few days of in vitro culture and that live young can be obtained following fertilization and development of these oocytes. In addition, initiation of follicular growth from primordial follicles could be achieved in organ culture in vitro. Hence, when the two techniques were combined, all folliculogenesis (from the primordial stage to ovulation) could be achieved in vitro. The situation is more complex in primates/human owing to the lower number of follicles initiating growth per day and to the longer duration of folliculogenesis. A few reports suggest that preantral follicles can survive and grow in culture for a few days and one study demonstrates that in 2 months, follicles can grow from 150 microns to 1.6 mm in diameter. The short term interest of such studies is to improve our understanding of the mechanisms involved in basal folliculogenesis. In the longer term, such techniques may prove useful to maintain some reproductive potential to women submitted to total body irradiation, to improve the management of reproduction of women suffering from early menopause or to generate oocyte banks to donate oocytes.

Animals↗
PubMedDate not supplied

[Oocyte apoptosis: when, how, why?].

The store of primordial follicles used for folliculogenesis is formed during oogenesis. Its size is the consequence of three processes: oogonia multiplication, time of meiosis initiation and extent of loss of germ cells (atretic oogonia, oocytes at the pachytene stage and newly formed primordial follicles). Apoptosis is causing this loss but its mechanisms are poorly documented. Both death signals (TNT alpha, Fas ligand) and survival signals (LIF, kit ligand) are present in the embryonic gonad. The apoptotic cascade then involves bclz, bax and caspases since knock out of these genes alters the store of primordial follicles. Apoptosis also exists within primordial follicles in adult ovaries and involves oocyte death. Its control has not been extensively studied.

Adult↗