Chorionic gonadotropin secretion is associated with an inhibition of follicular growth and an improvement in oocyte competence for in vitro maturation in the mare

• Published in: Biology of reproduction Vol. 58; no. 3; pp. 760 - 768
• Main Authors: Goudet, G, Leclerq, L, Bezard, J, Duchamp, G, Guillaume, D, Palmer, E
• Format: Journal Article
• Language: English
• Published: Madison, WI Society for the Study of Reproduction 01.03.1998; Society for the Study of Reproduction - Oxford Academic
• Subjects: Animals; Biological and medical sciences; CELL CULTURE; Chorionic Gonadotropin - blood; Chorionic Gonadotropin - metabolism; Computer Science; CRECIMIENTO; CROISSANCE; CULTIVO DE CELULAS; CULTURE DE CELLULE; Estrogens - blood; EXPERIMENTACION IN VITRO; EXPERIMENTATION IN VITRO; FECONDATION; FECUNDACION; Female; FERTILIZATION; Fertilization in Vitro - veterinary; Fundamental and applied biological sciences. Psychology; GESTACION; GESTATION; GONADOTROPHINE; GONADOTROPIN RELEASE; GONADOTROPINAS; GONADOTROPINS; GRAAFIAN FOLLICLES; GROWTH; HORMONAS; HORMONE; Hormone metabolism and regulation; HORMONES; Horses - physiology; IN VITRO EXPERIMENTATION; IN VITRO FERTILIZATION; In Vitro Techniques; INHIBICION; INHIBITION; JUMENT; Life Sciences; MADURACION; Mammalian female genital system; MARES; MATURATION; OOCYTE CULTURE; OOCYTE MATURATION; Oocytes - cytology; Oocytes - growth & development; Oocytes - physiology; OVA; OVAIRE; Ovarian Follicle - physiology; OVARIES; OVARIOS; OVULE; OVULO; PREGNANCY; Progesterone - blood; Punctures; SECRECION; SECRETION; Vertebrates: reproduction; YEGUA; 17β-Estradiol; Germinal cell; Fecundation; In vitro; Ovarian hormone; Ovary; Vertebrata; Mammalia; Female genital system; Horse; Chorionic gonadotrophin; Perissodactyla; Hormonal investigation; Progesterone; Sex steroid hormone; Ovarian follicle; Ungulata; Oocyte; Oocyte maturation
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod58.3.760

This study reports the follicular growth and oocyte competence for in vitro maturation and fertilization under the influence of circulating eCG. Three to 7 successive ultrasound-guided follicular punctures were performed on 4 pregnant mares from Day 23 until Day 75 of pregnancy and on 5 control mares whose embryonic vesicle was crushed on Day 22. All follicles larger than 5 mm were punctured 24 h after the largest follicle reached 18 mm. Expanded cumulus oocyte complexes (COCs) were stained at recovery to analyze the nuclear stage. Compact COCs were cultured in vitro for 46 h and either stained or processed for in vitro fertilization (IVF) and stained 26 h after IVF. In the control group, no mares showed an increase in eCG levels, whereas all the pregnant mares had concentrations higher than 100 ng/ml from Day 37. The number of follicles flushed during each puncture attempt significantly decreased with time for 3 of 4 pregnant mares. No significant change in this number was observed for the 5 control mares. The maturation rate of the oocytes from follicles 10-14 mm was significantly higher in the pregnant vs. the control group (14 of 17, 82%, vs. 13 of 30, 43%). The difference was not significant for the oocytes from follicles smaller than 9 mm or larger than 15 mm. After IVF, no oocyte was fertilized. The results led us to conclude that eCG is associated with an inhibition of follicular growth and an improvement in oocyte competence for in vitro maturation.