Home About us Contact
|
Home About us Contact | ||
|
|
||
Ovulatory Follicle (ovulatory + follicle)
Selected AbstractsCase of Pregnancy in Two Cows with Unicorn Horn of the Uterus either by Artificial Insemination at Ipsilateral or Embryo Transfer at Contralateral Corpus Luteum in the OvaryREPRODUCTION IN DOMESTIC ANIMALS, Issue 3 2008C Moriyama Contents Two Holstein heifers and a cow were diagnosed with White Heifer Disease by ultrasonography. Case 1 was a 14 month-old heifer with aplasia of both sides of the uterine horn. In case 2, a primiparous cow and case 3, an 18 month-old heifer, both showed aplasia of the right uterine horn. Case 2 became pregnant by artificial insemination at ipsilateral ovulatory follicle and corpus luteum in the left ovary, while case 3 became pregnant by embryo transfer at 7 days after oestrus with contralateral corpus luteum in the right ovary. [source] Changes in Plasma Concentrations of LH, FSH, Estradiol 17- , and Progesterone During Oestrus in Mithun (Bos frontalis)REPRODUCTION IN DOMESTIC ANIMALS, Issue 2 2006A Dhali Contents The objective of the present study was to establish the changes in plasma concentrations of LH, FSH, estradiol 17- , (E2) and progesterone (P4), as well as to understand their temporal relationships during oestrus in mithun (Bos frontalis). The experiment was conducted on 11 mithuns during third or fourth postpartum oestrous cycle. Since oestrus onset the jugular vein blood samples were collected every 2 h for 72 and 96 h, respectively from the animals without and with standing heat. The LH, FSH, E2 and P4 concentrations were estimated in plasma. The P4 concentration was fluctuated throughout the oestrus period and the average P4 concentration was found significantly (p < 0.05) lower on the day of oestrus onset. The multiple rises in LH and FSH concentrations above the basal level in spike like fashion were observed throughout the oestrus period irrespective of the occurrence of standing heat. A significant (p < 0.01) gradual increase in the average daily E2 concentration was observed till day 2 following oestrus onset irrespective of the occurrence of standing heat. A significant (p < 0.05) simultaneous increase in LH, FSH and E2 concentrations and a transient increase in P4 concentration at approximately the time of standing heat onset were observed. During investigation a definite temporal coupling between LH and FSH rises was absent throughout the oestrus period. The results suggest that (1) the multiple short-duration low-amplitude LH and FSH surges during oestrus may be crucial for the final maturation of ovulatory follicle and subsequent ovulation in mithun; (2) a differential mechanism for controlling LH and FSH secretions probably exists in mithun. [source] Actions of glucocorticoid and their regulatory mechanisms in the ovaryANIMAL SCIENCE JOURNAL, Issue 2 2007Masafumi TETSUKA ABSTRACT Glucocorticoid (G) directly modulates ovarian functions through binding to G receptor. The actions of G are both agonistic and antagonistic depending on the developmental stage of follicles and corpora lutea (CL). During follicular maturation, G suppresses follicular differentiation by downregulating expression of P450 aromatase and luteinizing hormone (LH) receptor in granulosa cells. During ovulation, G protects the ovulatory follicle from inflammatory damage and promotes luteinization, ensuring a smooth transition of the follicle to CL. Throughout life the ovary is exposed to periodic and sporadic waves of G. The Ovary appears to cope with this situation by locally modulating levels of active G. The primary regulatory mechanism consists of two isoforms of 11,-hydroxysteroid dehydrogenase (11,HSD) that catalyze conversion between active and inactive G. During follicular maturation the levels of active G are suppressed by the dehydrogenase activity of 11,HSD, whereas during the ovulatory process, levels of active G are further increased by the oxo-reductase activity of 11,HSD. The expression of these enzymes is under the control of gonadotrpins and local regulatory factors such as cytokines, allowing the mechanism to act in coordination with major reproductive events. Thus the G system is an integral part of ovarian physiology, which ensures that the ovary experiences only beneficial effects of G. [source] Regulation of uterine function by cytokines in cows: Possible actions of tumor necrosis factor-,, interleukin-1, and interferon-,ANIMAL SCIENCE JOURNAL, Issue 3 2006Kiyoshi OKUDA ABSTRACT When animals do not become pregnant, regression of the corpus luteum (CL) is essential for normal cyclicity because it allows the development of a new ovulatory follicle. Luteal regression is caused by a pulsatile release of prostaglandin (PG) F2, from the uterus in the late luteal phase in most mammals including cattle. Although it has been proposed in ruminants that pulsatile PGF2, secretion is generated by a positive feedback loop between luteal and/or hypophyseal oxytocin and uterine PGF2,, the bovine endometrium may possess other mechanisms for initiation of luteolytic PGF2, secretion. There is increasing evidence that several cytokines mainly produced by immune cells modulate CL and uterine function in many species. Tumor necrosis factor-, (TNF-,) stimulates PGF2, output from bovine endometrium not only at the follicular phase but also at the late luteal phase. Administration of TNF-, at a high concentration prolongs luteal lifespan, whereas administration of a low concentration of TNF-, accelerates luteal regression in cows. The data obtained from the authors' previous in vitro and in vivo studies strongly suggest that TNF-, is a crucial factor in regulating luteolysis in cows. The authors' recent study has shown that interleukin-1, mediates PG secretion from bovine endometrium as a local regulator. Furthermore, interferon-, (IFN-,) suppresses the action of TNF-, on PGF2, synthesis by the bovine endometrium in vitro, suggesting that IFN-, plays a luteoprotective role by inhibiting TNF-,-induced PGF2, production in early pregnancy. The purpose of the present review is to summarize current understanding of the endocrine mechanisms that regulate uterine function by cytokines during the estrous cycle and early pregnancy in cows. [source] Induction of alpha-caveolin-1 (,CAV1) expression in bovine granulosa cells in response to an ovulatory dose of human chorionic gonadotropinMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 11 2006Mame Nahé Diouf Abstract Caveolins are implicated in endocytosis, cholesterol trafficking and signal transduction. A cDNA fragment corresponding to caveolin-1 (CAV1) was identified in a mRNA profiling expression study in bovine granulosa cells (GC) following human chorionic gonadotropin (hCG)-induced ovulation. Thus, we have characterized CAV1 cDNA and studied its spatio-temporal expression pattern in bovine ovarian follicles. The full-length bovine ,CAV1 cDNA was cloned and encodes a putative 22 kDa protein. Expression of ,CAV1 was studied in bovine GC obtained from follicles at different developmental stages: small follicles (SF: 2,4 mm), dominant follicles (DF), ovulatory follicles (OF: 24 hr post-hCG), and corpus luteum (CL). Semiquantitative RT-PCR analysis showed a 6.5-fold increase in ,CAV1 mRNA in GC of OF versus DF (P,<,0.0001), whereas CAV2 mRNA was increased by only twofold (P,<,0.0007). Temporal expression of ,CAV1 mRNA from OF recovered at 0, 6, 12, 18, and 24 hr after hCG injection showed an 8.5-fold increase of ,CAV1 mRNA after 24 hr compared to 0 hr (P,<,0.0018) whereas no significant variation was detected for CAV2. Immunoblot demonstrated an initial increase in ,CAV1 protein level 12 hr post-hCG, reaching a maximum at 24 hr. Immunohistochemical localization of CAV1 was observed in GC of OF isolated 18 and 24 hr after hCG injection, whereas no signal was detected in GC of DF and SF. The induction of ,CAV1 in GC of OF suggests that ,CAV1 likely contributes to control the increase in membrane signaling that occurs at the time of ovulation and luteinization. Mol. Reprod. Dev. 73: 1353,1360, 2006. © 2006 Wiley-Liss, Inc. [source] | ||||||||||