Partial ablation of endometrial glands in dogs after exposure to progestin during the neonatal period

Bitches with uteri devoid of endometrial glands should be sterile, and consequently could contribute to the population control of dogs. Considering that an inadequate exposure of the female reproductive system to steroids can lead to the formation of the uterine gland knock-out (UGKO) phenotype in some species, the aim of this study was to evaluate the effect of serial applications of medroxyprogesterone acetate (MPA) from birth until the age of six months on the development of endometrial glands in bitches. For this purpose, 16 female mongrel dogs from different litters were distributed into either an MPA group (n = 8), animals treated with 10 mg kg sc (Promone-E®, Pfizer, Brasil) at 3-week intervals, from day one after birth until the age of six months, or a control group (n = 8), composed of animals that only received a 0.9% NaCl solution in place of MPA. At six months of age, ovariohysterectomy was performed and uterine horn samples were collected for histological and immunohistochemical examinations. The bitches from the MPA-treated group presented a 35% decrease in the number of endometrial glands, a larger diameter of the endometrial glands, a greater epithelial height, as well as a greater thickness of the uterine wall, endometrium, and myometrium. However, no significant differences were observed between the two groups in the expression of ER-α, ER-β, and PR on the surface epithelium and endometrial stroma. Therefore, the serial application of MPA from birth until the age of 6 months do not completely ablate the development of the endometrial glands in bitches, but impair it by 35%.

Partial ablation of endometrial glands in dogs after exposure to progestin during the neonatal period

Bitches with uteri devoid of endometrial glands should be sterile, and consequently could contribute to the population control of dogs. Considering that an inadequate exposure of the female reproductive system to steroids can lead to the formation of the uterine gland knock-out (UGKO) phenotype in some species, the aim of this study was to evaluate the effect of serial applications of medroxyprogesterone acetate (MPA) from birth until the age of six months on the development of endometrial glands in bitches. For this purpose, 16 female mongrel dogs from different litters were distributed into either an MPA group (n = 8), animals treated with 10 mg kg sc (Promone-E®, Pfizer, Brasil) at 3-week intervals, from day one after birth until the age of six months, or a control group (n = 8), composed of animals that only received a 0.9% NaCl solution in place of MPA. At six months of age, ovariohysterectomy was performed and uterine horn samples were collected for histological and immunohistochemical examinations. The bitches from the MPA-treated group presented a 35% decrease in the number of endometrial glands, a larger diameter of the endometrial glands, a greater epithelial height, as well as a greater thickness of the uterine wall, endometrium, and myometrium. However, no significant differences were observed between the two groups in the expression of ER-α, ER-β, and PR on the surface epithelium and endometrial stroma. Therefore, the serial application of MPA from birth until the age of 6 months do not completely ablate the development of the endometrial glands in bitches, but impair it by 35%.(AU)

Partial ablation of endometrial glands in dogs after exposure to progestin during the neonatal period.

Bitches with uteri devoid of endometrial glands should be sterile, and consequently could contribute to the population control of dogs. Considering that an inadequate exposure of the female reproductive system to steroids can lead to the formation of the uterine gland knock-out (UGKO) phenotype in some species, the aim of this study was to evaluate the effect of serial applications of medroxyprogesterone acetate (MPA) from birth until the age of six months on the development of endometrial glands in bitches. For this purpose, 16 female mongrel dogs from different litters were distributed into either an MPA group (n = 8), animals treated with 10 mg kg sc (Promone-E®, Pfizer, Brasil) at 3-week intervals, from day one after birth until the age of six months, or a control group (n = 8), composed of animals that only received a 0.9% NaCl solution in place of MPA. At six months of age, ovariohysterectomy was performed and uterine horn samples were collected for histological and immunohistochemical examinations. The bitches from the MPA-treated group presented a 35% decrease in the number of endometrial glands, a larger diameter of the endometrial glands, a greater epithelial height, as well as a greater thickness of the uterine wall, endometrium, and myometrium. However, no significant differences were observed between the two groups in the expression of ER-α, ER-ß, and PR on the surface epithelium and endometrial stroma. Therefore, the serial application of MPA from birth until the age of 6 months do not completely ablate the development of the endometrial glands in bitches, but impair it by 35%.

Sazonalidade na dinâmica folicular ovariana e produção embrionária em novilhas da raça Guzerá / Ovarian follicular dynamic and embryo production seasonality in Guzerá heifers breed

Objetivou-se avaliar os efeitos da sazonalidade sobre a dinâmicafolicular ovariana e analisar a influência de temperaturas elevadas no desenvolvimento embrionário inicial em novilhas da raça Guzerá.Seis animais foram sincronizados e o dia do estro foi considerado D0. A dinâmica folicular foi acompanhada por dois ciclos estrais consecutivos, na época 1 (verão) e 2 (inverno), utilizando-se um ultrasom Scanner 200 Vet (Pie Medical). Após nove dias do término dosegundo ciclo estral, todos os animais iniciaram o tratamento superovulatório, com duração de quatro dias. Os animais foram inseminados artificialmente, 12 e 24 horas após a detecção do estro. A coleta dos embriões foi realizada sete dias após a primeira inseminação. Houve efeito sazonal no número de ondas foliculares, com maior prevalência de ciclos com uma onda no verão. O intervalo estral e ovulatório apresentaram maior duração no verão. Foi encontrado efeito significativo de época sobre a duração do crescimento do folículo ovulatório, ocorrendo maior persistência no verão. A taxa de crescimento folicular foi menor no verão. A temperatura retal oscilou entre as épocas, evidenciando a influência (P< 0,05) da estação do ano sobre a temperatura corporal interna. O THI (índice de temperatura e umidade) observado no verão foi 94 e no inverno 86, sugerindo a condição de estresse dos animais. O número de estruturas viáveis foi maior na época 2, sugerindo os efeitos de época sobre a fertilização dos oócitos. As concentrações de progesterona não apresentaram efeito de época. As alterações na dinâmica folicular em decorrência do estresse térmico, tais como, taxa de crescimento folicular diminuída e aumento na duração do crescimento folicular, podem comprometer a qualidade do oócito e afetar a subseqüente funcionalidade do corpo lúteo.(AU)

The objective was to verify the effects of seasonality on ovarian follicular dynamic and evaluate the influence of heat stress on early embrionic development in Guzerá heifers. Six animals were sincronized and the estrus day was considered D0. Follicular dynamic was followed by two consecutive estrous cycles, at times 1 (summer) and 2 (winter),using an ultrasonographic Scanner 200 Vet (Pie Medical). After nine days of the end of second estrous cycle, all the animals were submitted to superovulatory treatment, with duration of four days. The animals were artificially inseminated, 12 to 24 hours after estrus detection. Embryo collection was realized seven days after the first insemination.There was seasonal effect on the number of follicular waves, with agreater prevalence of cycles with one wave in the summer. The intervals between estrus and ovulations showed a greater duration in the summer. There was a significant effect of time on the duration of the ovulatory follicle growth that was longer in the summer. The follicular growth rate was smaller in the summer. Rectum temperature oscillated between times, become evident the influence (P < 0.05) of season on the internal body temperature. The THI observed on summer was94 and winter was 86, these values suggest the animal stress condition.The number of viable structures was higher in winter, suggesting the effects on time 2 on fertilization of the oocytes. Progesterone concentrations did not have seasonal effect. Thermal stress alterations on follicular dynamic, such do reduced follicular growth rate and increase on duration of follicular growth. Might prejudice the quality of oocyte and affect the subsequent corpus luteum functionality.(AU)

Sazonalidade na dinâmica folicular ovariana e produção embrionária em novilhas da raça Guzerá / Ovarian follicular dynamic and embryo production seasonality in guzera heifers breed

Objetivou-se avaliar os efeitos da sazonalidade sobre a dinâmicafolicular ovariana e analisar a influência de temperaturas elevadas no desenvolvimento embrionário inicial em novilhas da raça Guzerá.Seis animais foram sincronizados e o dia do estro foi considerado D0. A dinâmica folicular foi acompanhada por dois ciclos estrais consecutivos, na época 1 (verão) e 2 (inverno), utilizando-se um ultrasom Scanner 200 Vet (Pie Medical). Após nove dias do término dosegundo ciclo estral, todos os animais iniciaram o tratamento superovulatório, com duração de quatro dias. Os animais foram inseminados artificialmente, 12 e 24 horas após a detecção do estro. A coleta dos embriões foi realizada sete dias após a primeira inseminação. Houve efeito sazonal no número de ondas foliculares, com maior prevalência de ciclos com uma onda no verão. O intervalo estral e ovulatório apresentaram maior duração no verão. Foi encontrado efeito significativo de época sobre a duração do crescimento do folículo ovulatório, ocorrendo maior persistência no verão. A taxa de crescimento folicular foi menor no verão. A temperatura retal oscilou entre as épocas, evidenciando a influência (P< 0,05) da estação do ano sobre a temperatura corporal interna. O THI (índice de temperatura e umidade) observado no verão foi 94 e no inverno 86, sugerindo a condição de estresse dos animais. O número de estruturas viáveis foi maior na época 2, sugerindo os efeitos de época sobre a fertilização dos oócitos. As concentrações de progesterona não apresentaram efeito de época. As alterações na dinâmica folicular em decorrência do estresse térmico, tais como, taxa de crescimento folicular diminuída e aumento na duração do crescimento folicular, podem comprometer a qualidade do oócito e afetar a subseqüente funcionalidade do corpo lúteo.

The objective was to verify the effects of seasonality on ovarian follicular dynamic and evaluate the influence of heat stress on early embrionic development in Guzerá heifers. Six animals were sincronized and the estrus day was considered D0. Follicular dynamic was followed by two consecutive estrous cycles, at times 1 (summer) and 2 (winter),using an ultrasonographic Scanner 200 Vet (Pie Medical). After nine days of the end of second estrous cycle, all the animals were submitted to superovulatory treatment, with duration of four days. The animals were artificially inseminated, 12 to 24 hours after estrus detection. Embryo collection was realized seven days after the first insemination.There was seasonal effect on the number of follicular waves, with agreater prevalence of cycles with one wave in the summer. The intervals between estrus and ovulations showed a greater duration in the summer. There was a significant effect of time on the duration of the ovulatory follicle growth that was longer in the summer. The follicular growth rate was smaller in the summer. Rectum temperature oscillated between times, become evident the influence (P < 0.05) of season on the internal body temperature. The THI observed on summer was94 and winter was 86, these values suggest the animal stress condition.The number of viable structures was higher in winter, suggesting the effects on time 2 on fertilization of the oocytes. Progesterone concentrations did not have seasonal effect. Thermal stress alterations on follicular dynamic, such do reduced follicular growth rate and increase on duration of follicular growth. Might prejudice the quality of oocyte and affect the subsequent corpus luteum functionality.