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Results for “Proestrus”

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At least 127 records · Page 7Linked to original sources
PubMed1985

Porcine follicular fluid treatment at proestrus diminishes the serum progesterone level of rats in early pregnancy.

Proestrous rats were treated with porcine follicular fluid (pFF) or porcine serum (pS) extract, afterwards they were put with males together. Next morning, the sperm positive females were considered as day 1 pregnant animals. On days 2, 8 and 14 of pregnancy serum progesterone level was determined by RIA. On days 2 and 8 of pregnancy serum progesterone level of pFF treated animals was significantly lower than that of pS treated ones, but it was not different from the controls on day 14 of pregnancy. The decreased progesterone level indicates that there are biologically active endogenous substances in the pFF (presumably inhibin or granulosa cell luteinization inhibitor) which may responsible for some forms of corpus luteum insufficiency and for some unexplained infertility cases.

Animals↗
PubMed1978

Cytological changes associated with the functions of the oviduct epithelium during proestrus and estrus in impala, Aepyceros melampus (Lichtenstein, 1812).

This study was carried out on the ampulla epithelium of the oviduct of impala of various ages. The morphological and ultrastructural features of the component epithelial cells were described. The cytological events which take place in the various cell types were documented and discussed. 2 cell types, the ciliated and nonciliated, constituted the cell population of the epithelium. The absence of glycogen in the epithelial cells was recognised.

Animals↗
PubMed2006

Influence of short-term fasting during the luteal phase of the estrous cycle on ovarian follicular development during the ensuing proestrus of ewes.

Short-term fasting of mature ewes during diestrus results in increased serum concentrations of progesterone and a delayed pre-ovulatory surge release of LH. To determine if these changes in reproductive hormones influence subsequent follicular development, mature ewes observed in estrus were assigned randomly to control (n=10) or fasted (n=15) groups. Control ewes had ad libitum access to feed, whereas fasted ewes were not fed from day 7 through 11 of their estrous cycle. Daily blood samples were collected from control and fasted ewes throughout the fasting period. Fasting increased (P<0.001) serum concentrations of progesterone (4.4 ng/mL versus 2.7 ng/mL [+/-0.3]). On day 12, all ewes were treated with 10mg of PGF(2alpha) and fasted ewes were returned to ad libitum feed. Ovaries were collected from ewes (n=5 each group) at 0 and 72 h following PGF(2alpha) in control and 0, 72 and 96 h in fasted ewes. Ovaries were weighed and small (< or =2mm), medium (3-4mm), and large (> or =5mm) follicles were enumerated. Total numbers of follicles were less (P<0.001) in fasted than fed ewes (14.6 versus 30.2 [+/-2.2]) at 0 h, but did not differ (P=0.9) when numbers of follicles were compared at similar times before the anticipated LH surge (i.e., at 72 h versus 96 h in control and fasted ewes, respectively). Within follicular size class, numbers of small and medium follicles were decreased (P=0.04) at 0 h in fasted ewes. Numbers of large follicles did not differ (P=1.0) between groups. Although numbers of small and medium ovarian follicles in fasted ewes recovered by 96 h to values comparable to fed ewes at 72 h following PGF(2alpha), serum concentrations of estradiol 17beta (P=0.08) and FSH (P=0.06) tended to be decreased in fasted ewes before the anticipated surge release of LH. Pituitary content of LH and FSH also tended to be lower (P< or =0.09) at 96 h in fasted ewes than at 72 h in control ewes, but did not differ (P> or =0.4) at hour 0 following PGF(2alpha). Hypothalamic and stalk median eminence contents of GnRH were not influenced (P> or =0.2) by fasting at any time period. Fasting during the luteal phase perturbs gonadotropin secretion and may influence fertility by causing a delay in ovarian follicle development.

Animals↗
PubMed1999

Induction of ovulation with gonadotropin-releasing hormone during proestrus in cattle: influence on subsequent follicular growth and luteal function.

Induction of ovulation by administration of gonadotropin-releasing hormone (GnRH) is commonly practiced in cattle to treat repeat breeders or cows exhibiting long estrous periods. This treatment may, however, disturb normal reproductive functions if timing is incorrect. The objective of the present study was to investigate the effect of exogenous GnRH on estradiol secretion of the ovulatory follicle, occurrence of ovulation, development and function of the corpus luteum (CL) and growth of a dominant follicle after ovulation in the bovine, when GnRH treatment was given before the expected physiological LH-surge. Luteolysis was induced by cloprostenol (PG) in three cows and six heifers. Every animal was assigned once to each of the following treatment or control manipulations, receiving either a single dose (0.1 mg) of GnRH (gonadorelin) at (1) 24 h (T1), (2) 48 h (T2), or (3) 72 h (T3) after PG, or (4) no gonadorelin (control manipulation, C). Ovaries were scanned by ultrasound and blood samples were collected for progesterone (P4) and estradiol-17beta (E-17beta) determination. Growth curves of dominant follicles between treatment I and the control differed significantly (P < 0.01). One day after ovulation, the diameter of the dominant follicle was almost 1 mm larger in T1. This difference remained almost unchanged during the entire follow-up period. The recruitment of a new follicular wave after ovulation seemed to occur earlier. Development of CL and levels and profiles of P4-production remained unaffected. When GnRH was given 1 day after PG injection, two animals showed significantly different development of CL (P < 0.05) and of P4-production (both in concentrations [P < 0.05] and profile [P < 0.01]). After normal ovulation and CL development, luteolysis took place on days 5 or 6 after ovulation, and animals ovulated on days 9 and 10. It is suggested that early induction of ovulation with GnRH can cause shortened luteal function in cattle and, ultimately, reduced fertility.

Animals↗