Gonadotropins are hormones that play a significant role in the reproductive physiology of horses. They are primarily produced by the pituitary gland and include luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These hormones regulate various aspects of equine reproduction, such as the development and function of the ovaries in mares and the testes in stallions. Gonadotropins influence processes like follicular growth, ovulation, and spermatogenesis. Their levels and activity are subject to regulation by factors such as seasonality and age, affecting reproductive efficiency in horses. This page compiles peer-reviewed research studies and scholarly articles that explore the function, regulation, and implications of gonadotropins in equine reproductive health.
Brück I, Bézard J, Baltsen M, Synnestvedt B, Couty I, Greve T, Duchamp G.In mares, the shortage of oocytes and the variability in nuclear maturation at a certain time of the oestrous cycle hinders the optimization of methods for in vitro maturation and in vitro fertilization. Increasing the number of small-to-medium-sized follicles available for aspiration in vivo may increase the overall oocyte yield. The aims of the present study were to investigate whether administration of crude equine gonadotrophins affects follicular development, oocyte recovery rate, in vivo oocyte maturation and follicular concentrations of meiosis-activating sterols. During oestrus, all fo...
McFarlane JR, Coulson SA, Papkoff H.This study describes the presence of immunoactive and bioactive eCG-like material in full-term placentas of both domestic horses and zebras. Term placental extracts were immunoreactive in an LH monoclonal antibody RIA, and methods successfully used previously for the purification of eCG and eLH were employed to further concentrate the immunoreactive materials to the point where additional characterization studies could be performed. Sufficient equine material was obtained to perform a final fractionation on a concanavalin A Sepharose column yielding an unadsorbed fraction, e17A, and an adsorbe...
Driancourt MA.In this review, the main features of folliculogenesis are summarized and compared among species. In the past few years, ultrasonography has clarified follicle growth patterns, and our understanding of follicle maturation has improved considerably. As the follicles develop towards the ovulatory stage, three features appear to be highly conserved across all species: 1) the sequence of events (recruitment, selection and dominance); 2) the sequential need for gonadotropins (FSH for recruitment, LH for dominance) and 3) the large variability of numerical parameters (number of waves per cycle, numbe...
Visutakul P, Bell ET, Loraine JA, Fisher RB.Human chorionic gonadotrophin (HCG), pregnant mare serum gonadotrophin (PMSG) and human menopausal gonadotrophin (HMG) were incubated with varying concentrations of urea at different temperatures for different times.
The luteinizing hormone (LH) activity of HCG was progressively destroyed with increasing concentrations of urea. The degree of inactivation was greater at higher temperatures but the time of incubation did not affect the results.
The follicle-stimulating activity of PMSG was reduced at high urea concentrations; the time of incubation was without effect.
Under the experime...
Khan IU, Khairullah AR, Khan AY, Rehman AU, Mustofa I.This review explores advanced strategies for enhancing fertility and optimizing reproductive outcomes in equine breeding programs. Horses, being seasonal breeders, present unique reproductive challenges influenced by environmental and physiological factors such as photoperiods, hormone cycles, and aging. Key approaches discussed include hormonal therapies, artificial light manipulation, and nutritional supplementation to improve ovulation and conception rates during the breeding season. Specific hormones such as gonadotropin-releasing hormone analogs, equine follicle-stimulating hormone, and p...
de Castro Sasahara TH, Gomes SP, Abdala FCM, Schimming BC, Miglino MA.Sexual differentiation in the equine fetus involves coordinated morphogenetic processes that shape both the gonads and the genital ducts. Although the formation of testes and ovaries has been relatively well documented, the temporal dynamics and morphometric patterns of the mesonephric (Wolffian) and paramesonephric (Müllerian) ducts remain insufficiently characterized. This study aimed to detail the timeline of gonadal and ductal differentiation in male and female equine fetuses during the critical developmental window between 60 and 80 days of gestation. Gross anatomical evaluation, histo...
