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      Morfometría macroscópica del ovario y cuerpo lúteo de yeguas criollas de Colombia Translated title: Morfometria macroscópica do ovário e corpo lúteo de éguas criollas da Colômbia Translated title: Macroscopic Morphometry of the Ovary and Corpus Luteum of Native Mares in Colombia

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          Abstract

          El objetivo del presente estudio era realizar una descripción de parámetros morfométricos del ovario y cuerpo lúteo (CL) de yeguas criollas de Colombia. Se utilizaron cincuenta ovarios provenientes de yeguas adultas. Todos los animales se encontraban clínicamente sanos. Los tejidos se obtuvieron después del sacrificio y se fijaron inmediatamente en formalina tamponada. Se pesó y se midió el diámetro mayor y el menor del ovario. Se realizó una incisión longitudinal con la finalidad de observar el parénquima del órgano. Se removió el CL y se registró su peso y diámetro. Los datos se analizaron a través de estadística descriptiva y el grado de asociación de las variables se calculó a través de un modelo de regresión simple. Se transformaron los datos con logaritmo en base natural cuando se requirió. El diámetro mayor del ovario varió desde 2 hasta 6,2 cm. El diámetro del CL varió desde 1,1 hasta 3,6 cm. Se encontró una relación lineal entre el peso y el diámetro del ovario (R² = 0,41; p < 0,01) y entre el peso y el diámetro del CL (R² = 0,48; p < 0,01). Aunque la relación entre el peso del ovario y el cuerpo lúteo es lineal, el coeficiente de determinación fue muy bajo. La yegua criolla colombiana tiene características similares en la morfología ovárica y luteal a las reportadas en la literatura para yeguas de otras razas livianas. Los valores aquí reportados podrían ser el punto de partida para establecer valores de referencia de utilidad clínica.

          Translated abstract

          O objetivo do presente estudo era realizar uma descrição de parâmetros morfométricos do ovário e corpo lúteo (CL) de éguas criollas da Colômbia. Utilizaram-se cinquenta ovários provenientes de éguas adultas. Todos os animais se encontravam clinicamente saudáveis. Os tecidos foram obtidos depois do sacrifício e se fixaram imediatamente em formalina tamponada. Foi pesado e medido o diâmetro maior e o menor do ovário. Realizou-se uma incisão longitudinal com a finalidade de observar o parênquima do órgão. Removeu-se o CL e se registrou seu peso e diâmetro. Os dados se analisaram com estatística descritiva, e o grau de associação das variáveis se calculou através de um modelo de regressão simples. Transformaram-se os dados com logaritmo em base natural quando se requerido. O diâmetro maior do ovário variou desde 2 até 6,2 cm. O diâmetro do CL variou desde 1,1 até 3,6 cm. Encontrouse uma relação linear entre o peso e o diâmetro do ovário (R² = 0,41; p < 0,01) e entre o peso e o diâmetro do CL (R² = 0,48; p < 0,01). Enquanto que, ainda sendo linear a relação entre o peso do ovário e o corpo lúteo, o coeficiente de determinação foi muito baixo. A égua criolla colombiana tem características similares na morfologia ovárica e lútea a as relatadas na literatura para éguas de outras raças leves. Os valores aqui reportados poderiam ser o ponto de partida para estabelecer valores de referencia de utilidade clínica.

          Translated abstract

          The purpose of this study was to describe the morphometric parameters of the ovary and corpus luteum (CL) of native mares in Colombia. Fifty ovaries from adult mares were used. All animals were clinically healthy. The tissues were collected after slaughter and immediately fixed in buffered formalin. The large and small diameters of the ovary were weighted and measured. A longitudinal incision was made in order to observe organ parenchyma. The CL was removed and its weight and diameter were recorded. Data were analyzed with descriptive statistics, and the degree of association between the variables was calculated through a simple regression model. When required, data were transformed with natural base logarithm. The large diameter of the ovary ranged from 2 to 6.2 cm. The diameter of the CL ranged from 1.1 to 3.6 cm. A linear relationship was found between the weight and diameter of the ovary (R² = 0.41; p < 0.01) and between the weight and diameter of the CL (R² = 0.48; p < 0.01). On the other hand, although the relationship between the weight of the ovary and corpus luteum is linear, the determination coefficient was very low. Luteal and ovarian morphology of native mares in Colombia has similar characteristics to those reported in literature for other light breed mares. The values reported herein could be the starting point to establish reference values for clinical utility.

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          Most cited references22

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          Reproductive cycles of horses.

          Horses are long-day breeders. During the breeding season, cycle length is about 22 days with 5-7 days of oestrus. Gonadotroph cells are localized in the pars distalis as well the pars tuberalis of the pituitary and heterogeneity in the pattern of LH and FSH storage within the gonadotroph population is considered the basis for the differential regulation of gonadotrophin secretion throughout the reproductive cycle. No short and distinct periovulatory LH peak exists in the mare. The equine ovary has an extreme large size and weight. One to two major follicular waves develop per cycle. The preovulatory follicle reaches an average size of 40 mm. Only granulosa cells develop into luteal cells. Progesterone increases at the time of ovulation and reaches maximal concentrations on day 8. Functional luteolysis occurs around day 15 and is initiated by endometrial secretion of PGF(2α). In contrast to other species, no significant luteal oxytocin synthesis exists in the mare. During the oestrous cycle, uterus, vagina and endometrium undergo pronounced changes related to variations in the endocrine milieu. Seasonal reproductive activity is stimulated by photoperiod together with exogenous factors. The anovulatory season can be differentiated into an autumn transitional phase, a mid-anovulatory period and a spring transitional phase bringing the mare back into cyclic activity. During the mid-anovulatory period, follicular development is minimal. The beginning of the spring transitional period is characterized by the development of 1-3 anovulatory follicular waves before ovulation occurs and the most important factor for the re-initiation of ovulatory activity is the occurrence of repeated pronounced increases in circulating LH.
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            Follicle growth, corpus luteum function and their effects on embryo development in postpartum dairy cows.

            Absent or irregular ovarian cycles in lactating dairy cows are caused by failure to ovulate the dominant follicle at the appropriate time. The follicle then either regresses or develops into a cyst. This process can be triggered by a variety of metabolic and disease factors that act at the hypothalamus and pituitary gland to inhibit pulsatile LH secretion and the LH surge, and at the ovary to reduce follicular growth and oestradiol production. Cows of poor energy status have low circulating concentrations of insulin-like growth factor I (IGF-I). Predisposing factors include calving difficulties, inappropriate diet, reduced intake of dry matter and a high rate of body condition score loss. Various stressors predispose the follicle to cyst development by inhibiting the LH surge and ovulation; these include common infections, such as mastitis. Even when ovulation does occur, poor follicular development may result in production of an inadequate corpus luteum. The timing of the increase in progesterone in the early luteal phase (days 4-5) appears to be a key determinant of fertility, probably because it alters the secretory activity of the reproductive tract, thus influencing embryonic growth and interferon-tau production. A period of negative energy balance after calving can reduce fertility even though metabolic parameters have apparently improved at the time of service.
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              A comparative study of the corpus luteum.

              R. GEMMELL (1995)
              The corpus luteum (CL) is a transitory organ which has a regulatory role in reproduction. Sharks, amphibians and reptiles have corpora lutea that produce progesterone which influences the rate of embryonic development. The egg-laying monotremes and the two major mammalian groups, eutherian and marsupial, have a CL that secretes progesterone. Most eutherians have allowed for the uterine development of their young by extending the length of the oestrous cycle and the CL or placenta actively secretes progesterone until birth. Gestation in the marsupial does not extend beyond the length of an oestrous cycle and the major part of fetal development takes place in the pouch. Where the extension of the post-luteal phase in the eutherian has allowed for the uterine development of young, the marsupial has extended the pre-luteal phase of the oestrous cycle and has evolved an alternative reproductive strategy, embryonic diapause. The mechanism for the secretion of hormones from the CL has been controversial for many years. Densely-staining secretory granules have been observed in the CL of sharks, marsupials and eutherians. These granules have been reported to contain relaxin, oxytocin or mesotocin, and progesterone. A hypothesis to suit all available data is that all hormones secreted by the CL are transported within such granules. In conclusion, although there are obvious differences in the mode of reproduction in the two main mammalian groups, it is apparent that there is a great deal of similarity in the hormonal control of regression of the CL and parturition.
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                Author and article information

                Journal
                rmv
                Revista de Medicina Veterinaria
                Rev. Med. Vet.
                Universidad de La Salle (Bogotá, Distrito Capital, Colombia )
                0122-9354
                2389-8526
                December 2013
                : 26
                : 57-65
                Affiliations
                [03] Bucaramanga orgnameUniversidad Cooperativa de Colombia orgdiv1Grupo de Investigación en Ciencias Animales (Grica) Colombia miguel.bedoya@ 123456campusucc.edu.co
                [02] Bucaramanga orgnameUniversidad Cooperativa de Colombia orgdiv1Grupo de Investigación en Nutrición, Toxicología y Reproducción Animal (Grupontra) Colombia
                [01] Bucaramanga orgnameUniversidad Cooperativa de Colombia orgdiv1Grupo de Investigación en Nutrición, Toxicología y Reproducción Animal (Grupontra) Colombia
                [04] orgnameUniversidad Cooperativa de Colombia orgdiv1Grupo de Investigación en Nutrición, Toxicología y Reproducción Animal (Grupontra) angela.gonella@ 123456campusucc.edu.co
                Article
                S0122-93542013000200006 S0122-9354(13)00002606
                dbc8caf9-ce43-4ecc-b729-c94fa9505d71

                This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

                History
                : 19 September 2013
                : 19 October 2012
                Page count
                Figures: 0, Tables: 0, Equations: 0, References: 13, Pages: 9
                Product

                SciELO Colombia

                Categories
                Artículos

                gonads,morphology,luteal,Equines,morfologia,lútea,gônadas,equinos,morfología,gónadas

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