Abstract This study aimed to evaluate the effect of synchronization with prostaglandin F2α in Baixadeiro mares during the rainy and dry seasons. Fourteen mares were synchronized by administering two doses of 1 mL prostaglandin PGF 2α and monitored by rectal palpation and ultrasound for the assessment of follicular development and uterine echotexture. Of this total, nine mares allowed the collection of blood, in which the blood was collected by venipuncture of the jugular vein to determine progesterone (P4) by ELISA. Mares showed no differences (P > 0.05) in weight, body score condition (BSC), tone, uterine edema, frequency of ovulation, synchronization interval, estrus, and the total number of follicles between periods. However, there was a difference in large increased follicle diameter (P < 0.05) during the dry season. The average concentrations of P4 in mares differed (P < 0.05) between the pre- and post-ovulatory phases for both seasons and after ovulation, with higher concentrations in the rainy season. Furthermore, statistical differences in daily light (P < 0.05) were observed between the dry and rainy periods. Thus, we conclude that mares from the genetic grouping Baixadeiro showed no reproductive seasonality, though there was a difference in luminosity between the rainy and dry seasons. The treatment with two doses of PGF 2α was effective in synchronizing the mares, promoting the return of estrus in the dry and rainy periods. The mares remaining cyclically active throughout the year provided there were appropriate forage availability and quality levels to allow for normal values of body weight and condition.

SUMMARY: The rabbit is considered an ideal animal model for studies that describe abnormalities in the testicles due to the similar morphogenetic mechanisms of sexual development and diseases commonly found in humans. The aim of this study was to determine the male sexual differentiation of the New Zealand rabbit (Oryctolagus cuniculus) through development. The gestational age was estimated and classified as 9, 12, 14, 16, 18, 20, 23 and 28 gestational days. The morphological and sexual determination were performed by histological analysis of the reproductive tract in the embryos and fetuses (9-28 days) as well as by immunohistochemistry- Desert hedgehog-Dhh- (testis-specific protein on Y chromosome- 16, 20, 23 days and adult rabbits). Gonads were observed from the 14th day in an undifferentiated stage and with homogeneous aspect. Sexual differentiation was observed from the 16th day with presence of cells forming gonadal cords and Dhh+ cells in the gonadal parenchyma. From the 18th gestational day testicular cords were observed, which evolved into organized seminiferous tubules. The formation of the efferent ducts and ductus deferens and epididymis was observed on the 20th and 23rd days, respectively. The differentiation of the external genitalia occurred from the 23rd days from the anogenital distance and was identified to identify the penile structures. In summary, the features of the sexual differentiation were determined by observation of the Dhh+ protein in embryos from the 16th day to adulthood, and the morphological particularities observed from the 18th gestational day, determined by differentiation of the external genitalia from the 23rd day.

RESUMEN: El conejo se considera un modelo animal ideal para estudios que describen anomalías a nivel testícular debido a que presenta mecanismos morfogenéticos similares al desa- rrollo sexual y enfermedades que se encuentran comúnmente en los seres humanos. El objetivo de este estudio fue determinar la diferenciación sexual masculina del conejo de Nueva Zelanda (Oryctolagus cuniculus) a través del desarrollo. La edad gestacional se estimó y clasificó en 9, 12, 14, 16, 18, 20, 23 y 28 días gestacionales. La determinación morfológica y sexual se realizó mediante análisis histológico del tracto reproductivo en los embriones y fetos (9 - 28 días) así como mediante inmunohistoquímica -Desert hedgehog-Dhh- (proteína testicular específica en el cromosoma Y- 16, 20, 23 días y conejos adultos). Las gónadas se observaron a partir del día 14 en un estadio indiferenciado y con aspecto homogéneo. Se observó diferenciación sexual a partir del día 16 con presencia de células formadoras de cordones gonadales y células Dhh+ en el parénquima gonadal. A partir del día 18 de gestación se observaron cordones testiculares, que evolucionaron a túbulos seminíferos organizados. La formación de los conductos eferentes, deferentes y del epidídimo se observó a los 20 y 23 días, respectivamente. La diferenciación de los genitales externos ocurrió a partir del día 23 desde la distancia anogenital y se utilizó para identificar las estructuras del pene. En conclusión, las características de la diferenciación sexual se determinaron mediante la observación de la proteína Dhh en embriones desde el día 16 hasta la edad adulta, y las particularidades morfológicas observadas a partir del día 18 de gestación, determinadas por diferenciación de los genitales externos a partir del día 23.

Abstract The interaction between early embryo and maternal immune system for the establishment of pregnancy is the focus of several studies; however, it remains unclear. The maternal immune response needs to keep a balance between avoiding any damage to the conceptus and maintaining its function in combating microbes as well. When conceptus-maternal crosstalk cannot achieve this balance, pregnancy losses might occur. Intercommunication between mother and conceptus is fundamental during early pregnancy to dictate the outcome of pregnancy. In ruminants, the embryo reacts with the maternal system mainly via interferon tau (IFNT) release. IFNT can act locally on the embryo and endometrial cells and systemically in several tissues and cells to regulate their response via the expression of interferon-stimulated genes (ISGs). Also, IFNT can induce the expression of inflammatory-related genes in immune cells. Day 7 embryo induces a shift in the maternal immune response towards anti-inflammatory (Th2) immune responses. During maternal recognition of pregnancy, peripheral mononuclear cells (PBMCs) and polymorphonuclear cells (PMNs) express markers that configure an anti-inflammatory response. However, PMNs response is more sensitive to the effects of IFNT. PMNs are more likely to express interferon-stimulated genes (ISGs), transforming growth factor-beta (TGFB), interleukin 10 (IL10), and arginase-1 (ARG1), configuring one of the most rapid immune responses to early pregnancy. This review focus on the local and peripheral immune responses during early pregnancy in ruminants, mainly the PMNs function in the immune system.

SUMMARY: The aim of this study was to know the embryonic and fetal development of the female rabbit genital system (Oryctolagus cuniculus), describing its main phases and the moment of sexual differentiation. Eleven pregnant New Zealand female rabbits were used in different gestational phases. The day of coitus was determined as day 0. For each stage a minimum of two animals was considered. The samples were obtained every two days from the ninth day post-coitus (dpc) until the 28th dpc. The gestational period was divided in two: animals with undifferentiated sex (group 1) and animals with differentiated sex (group 2). The ages of embryos and fetuses were estimated through the crown-rump method. Subsequently, embryos and fetuses were dissected, fixed and processed to be embedded in paraffin (Histosec). The histological analysis was performed on sections stained with hematoxylin and eosin. Immunohistochemical analysis to determine sexual differentiation was performed on samples from the 16th, 18th and 28th dpc. Desert Hedgehog (Dhh) and Indian Hedgehog (Ihh) primary antibodies, respectively, were used to identify cells of the male and female germinal epithelium. The immunohistochemical results showed that at the 16th dpc, female sexual differentiation was evident, since positive expression of the Ihh protein was observed. Sexual differentiation was obtained through histological analysis on the 18th dpc and through anatomical observation of the external genitalia on the 24th dpc. Knowing the characteristics of the embryonic and fetal development of the female rabbit genital system as well as the moment of sexual differentiation make it possible to establish bases for future research that address the physiology and pathology of these organs. Thus, any alteration in the chain of events of sexual determination and differentiation must search for an explanation from the knowledge of the possible normal mechanisms affected.

RESUMEN: El objetivo de esta investigación fue conocer el desarrollo embrionario y fetal del sistema genital femenino de conejo (Oryctolagus cuniculus), describiendo sus principales fases y el momento de la diferenciación sexual. Se utilizaron 11 conejos hembras gestantes neozelandesas, en diferentes fases gestacionales. El día del coito se determinó como día 0. Para cada etapa fue considerado un mínimos de dos animales. Las muestras fueron obtenidas cada dos días, a partir del noveno día post-coito (dpc) hasta el 28 dpc. El periodo gestacional fue dividido en dos: animales con sexo indiferenciado (grupo 1) y, animales con sexo diferenciado (grupo 2). Las edades de los embriones y los fetos fueron estimadas a través del método de crown-rump. Posteriormente, embriones y fetos fueron disecados, fijados y procesados para su inclusión en parafina (Histosec). El análisis histológico se realizó en secciones teñidas con Hematoxilina y Eosina. El análisis inmunohistoquímico para determinar la diferenciación sexual fue realizado en muestras de 16, 18 y 28 dpc. Para identificar células del epitelio germinativo masculino y feminino se utilizaron los anticuerpos primarios Desert Hedgehog (Dhh) e Indian Hedgehog (Ihh), respectivamente. Los resultados inmunohistoquímicos mostraron que a los 16 dpc se evidenció diferenciación sexual femenina, ya que se observó expresión positiva de la proteína Ihh. La diferenciación sexual, a través del análisis histológico fue obtenida a los 18 dpc y a través de la observación anatómica de los genitales externos a los 24 dpc. Conocer las características del desarrollo embrionario y fetal del sistema genital femenino de conejo, así como, el momento de la diferenciación sexual, permiten sentar bases para futuras investigaciones que aborden la fisiología y patología de estos órganos. Así, cualquier alteración en la cadena de eventos de la determinación y diferenciación sexual deberá buscar una explicación a partir del conocimiento de los posibles mecanismos normales afectados.

RESUMO: Buscou-se estudar o desenvolvimento do pulmão do preá ( Galea spixii ) com ênfase nas características macroscópicas, histológicas e imunohistoquimicas, bem como acompanhar a proliferação celular. Para tanto, foram utilizados 8 fetos, os quais, de acordo com o tamanho (crown-rump - CR), foram divididos em 3 grupos: Grupo I (33-35 dias), Grupo II (38-40 dias) e Grupo III (43-45 dias). Macroscopicamente, não houve diferenças quanto à morfologia do pulmão entre os grupos. Em relação à maturação pulmonar, no grupo I, observou-se o início da formação dos brônquios e bronquíolos, os quais estavam rodeados por grande quantidade de mesênquima e vasos sanguíneos de pequeno calibre, caracterizando o estágio pseudoglandular. Os indivíduos do Grupo II apresentaram maior quantidade de formações tubulares no parênquima pulmonar, assim como redução da quantidade de mesênquima, atingindo, dessa forma, a fase canalicular. No Grupo III, os pulmões apresentaram-se completamente formados, atingindo a fase alveolar. Nas análises de imunohistoquimica, os pulmões dos indivíduos dos Grupos I e II apresentaram marcação para Pcna, Oct-4 e VEGF. Por outro lado, não houve marcação no Grupo III. A anatomia do pulmão do preá se assemelha ao pulmão da cutia ( Dasyprocta sp.) quanto ao número de lobos e fissuras. No que se refere ao desenvolvimento pulmonar, o pulmão do preá apresentou maior similaridade com o pulmão de fetos humanos, visto que ambos, ao nascer, encontram-se na fase alveolar, contrário a outras espécies de roedores.

ABSTRACT: The aim of this research was to study the development of the lung in Galea spixii , by gross anatomy, histological analysis and immunohistochemical techniques. Totally, 8 fetuses were used and allocated into three groups of age: Group I (33-35 days), Group II (38-40 days), and Group III (43-45 days) with given crown-rump - CR lenghts. According to the gross morphology, there were no differences in relation to the lung morphology among groups. In relation to lung maturation, the Group I showed early formation of the bronchi and bronchioles, which were richly surrounded by mesenchyme and small blood vessels, typical features of the pseudoglandular stage. Individuals from Group II showed higher amounts of tubular formations in the lung parenchyma and reduced mesenchyme, reaching the canalicular stage. The lung from individuals of the Group III was completely formed, reaching the alveolar phase. In the immunohistochemical analysis, the lung of individuals from both Groups I and II were positive for Pcna, Oct-4, and VEGF. In contrast, there was not labbeling on samples from Group III. Thus, the G. spixii lung anatomy resembles the agouti ( Dasyprocta sp.) lung, in relation to the number of lobes and fissures. In regard to the lung development, G. spixii showed more similarity with the human fetal lung, since both are born in the stage of the alveolar phase, different to other rodent species.