Synchronized Expansion and Contraction of Olfactory, Vomeronasal, and Taste Receptor Gene Families in Hystricomorph Rodents.

Chemical senses, including olfaction, pheromones, and taste, are crucial for the survival of most animals. There has long been a debate about whether different types of senses might influence each other. For instance, primates with a strong sense of vision are thought to have weakened olfactory abilities, although the oversimplified trade-off theory is now being questioned. It is uncertain whether such interactions between different chemical senses occur during evolution. To address this question, we examined four receptor gene families related to olfaction, pheromones, and taste: olfactory receptor (OR), vomeronasal receptor type 1 and type 2 (V1R and V2R), and bitter taste receptor (T2R) genes in Hystricomorpha, which is morphologically and ecologically the most diverse group of rodents. We also sequenced and assembled the genome of the grasscutter, Thryonomys swinderianus. By examining 16 available genome assemblies alongside the grasscutter genome, we identified orthologous gene groups among hystricomorph rodents for these gene families to separate the gene gain and loss events in each phylogenetic branch of the Hystricomorpha evolutionary tree. Our analysis revealed that the expansion or contraction of the four gene families occurred synchronously, indicating that when one chemical sense develops or deteriorates, the others follow suit. The results also showed that V1R/V2R genes underwent the fastest evolution, followed by OR genes, and T2R genes were the most evolutionarily stable. This variation likely reflects the difference in ligands of V1R/V2Rs, ORs, and T2Rs: species-specific pheromones, environment-based scents, and toxic substances common to many animals, respectively.

Lingual Ultrastructural and Histochemical Study in the Patagonian Mara (Rodentia: Caviidae, Dolichotis patagonum) in Relation to Other Hystricomorphs.

The study describes the ultrastructure of the tongue in the Patagonian mara (Dolichotis patagonum) using light and scanning electron microscopy. Histochemical methods were used for evaluation of lingual salivary glands. The tongue is divided into a small and rounded apex, a narrow corpus, and a significantly wider radix, with a well-developed lingual prominence. The tip of the apex is free of papillae. The caudal part of the apex and the corpus are covered by filiform papillae. Round fungiform papillae are scattered among them. Papillae on the narrow stalk are conical. The radix contains caudally bent papillae forming wide flat prominences, slender, hook shaped filiform papillae, foliate papillae, and two oval vallate papillae. Taste buds were found on the lateral sides of the foliate and vallate papillae. Purely serous salivary glands are beneath the vallate and foliate papillae. Serous acini and mucous tubules are in the lingual radix. The Patagonian mara is the only hystricomorph rodent with described hyaline cartilage strengthening the lingual radix. Some typical signs of adaptation to herbivorous diet were found. The structure of the tongue is adapted to grass-feeding, as grasses form the main component of their diet.

Hystricomorph Rodent Analgesia.

Limited information on the analgesic efficacy and safety of even clinically commonly used analgesic drugs in guinea pigs and chinchillas is available. Buprenorphine and meloxicam are currently the most common analgesics routinely used to treat painful conditions in guinea pigs and chinchillas. Hydromorphone has also shown to be an effective analgesic drug in these species, with limited adverse effects. Tramadol in chinchillas does not provide analgesia even at high doses, and no information is available on the efficacy of this drug in guinea pigs. Multimodal analgesic protocols should be considered whenever possible.

Cortisol resistance in the degu (Octodon degus).

Cortisol resistance has also been reported in the degu, Octodon degus, a New World hystricomorph endemic to central Chile. The degu is used as a model for studies of stress and diurnal rhythms, parental behaviour and female masculinization. Another New World hystricomorph, the guinea pig, also exhibits glucocorticoid resistance, a result of amino acid sequences that differ from other mammalian glucocorticoid receptors (GR). Mutations in the ligand-binding domain of the human GR have been identified in familial or sporadic generalised cortisol resistance as have variants in the guinea pig. To address the possibility that the high levels of cortisol observed in the degu are a result of the same or similar sequence variations observed in the guinea pig GR, we have cloned, expressed and characterised the ligand-binding domain (LBD) of the degu GR. Somewhat unexpectedly, neither the amino acids nor the region involved in the resistance observed in the guinea pig GR are relevant in the degu GR. The relative resistance to cortisol observed in the degu GR is conferred by the substitution of two isoleucine residues, which are highly conserved in the GR across species, with a valine doublet. These amino acids lie in the region between helices 5 and 6 of the GR LBD, a region known to be important in determining the affinity of ligand-binding in steroid receptors.

Fetal bone development in the lowland paca (Cuniculus paca, Rodentia, Cuniculidae) determined using ultrasonography.

Studying the timing of the main events of embryonic and fetal development may clarify the strategies adopted by species to maximize neonatal survival and the consequences of these events for their life history. This study describes bone development during the fetal phase of the lowland paca (Cuniculus paca), comparing it with other precocial or altricial species, and its relationship with the species' adaptive strategies. A total of 102 embryos/fetuses obtained over the course of 17 years through collaboration with local subsistence hunters in the Amazon were analyzed. Measurements of mineralization of the axial and appendicular skeletons were performed by ultrasonography using a 10-18-MHz linear transducer. The chronological order of occurrence of mineralization in relation to the total dorsal length (TDL) was: skull (TDL = 4.1 cm); vertebral bodies (TDL = 4.6 cm); scapula, humerus, radius, ulna, ilium, ischium, femur, tibia, and fibula (TDL = 6.7 cm); ribs (TDL = 7.8 cm); clavicle (TDL = 8.5 cm); metacarpi/metatarsi (TDL = 11 cm); phalanges (TDL = 15 cm); tarsus (TDL = 18 cm); patella (TDL = 23 cm); and carpus (TDL = 27.2 cm). Secondary ossification centers first appeared in the femoral distal epiphysis (TDL = 16.6 cm) and tibial proximal epiphysis (TDL = 18.4 cm). Advanced fetuses (TDL > 30 cm, 97% gestational period) presented mineralization in all primary and most secondary centers. Compared to other species, paca neonates have a well-developed skeletal system at birth, which is important for their independent postnatal locomotion. Our results may contribute to the monitoring of bone development in other wild species, helping us to understand their life history, and serving as parameters for comparisons between precocial and altricial mammals.

Development of urogenital system in the Spix cavy: A model for studies on sexual differentiation.

This study documented, for the first time, the morphological patterns of differentiation of male and female genital organs of Spix cavy (Galea spixii) using histological and ultrastructural analyses, with immuno-localization of steroidogenic enzymes, cytochromes P450 aromatase (P450arom) and 17α-hydroxylase/17, 20-lyase (P450c17), involved in the synthesis of estrogens and androgens respectively throughout fetal sexual development. Undifferentiated gonads of Spix cavy develop into ovaries in females after 25 days of gestation (DG), exhibiting P450arom immunoreactivity. After 25 DG, paramesonephric ducts develop and form oviducts, uterine horns and cranial portion of the vagina. The caudal portion of the vagina originates from the urogenital sinus, and a vaginal closure membrane is present at the end of gestation. Partial channeling of the urethra into the clitoris occurs after 40 DG, but complete channeling never occurs. A preputial meatus emerges near the tip of organ. In males, undifferentiated gonads develop into testes at 25 DG and develop immunoreactivity for P450c17, which is required for androgens synthesis and likely maintenance of mesonephric ducts. Mesonephric ducts develop subsequently, forming the epididymis and ductus deferens. The pelvic urethra develops after 25 DG with channeling into the penis occurring around 30 DG. This is the first morphological study describing the process of sexual differentiation during gestation in a hystricomorph rodent and one of the most comprehensive analyses conducted in any mammal. Male genital organ development follows the general pattern described in other domestic mammals, but does not include formation of the baculum as occurs in mice and rats. In females, clitoral development includes partial canalization by the urethra and development of a preputial meatus. Further studies are required to clarify the mechanisms involved in the differentiative processes described.

Added dietary vegetables and fruits improved coat quality of capybara in Seoul Zoo, Republic of Korea: A case study.

Adequate levels of dietary vitamin C are necessary for capybaras (Hydrochoerus hydrocharis) because they cannot synthesize the vitamin endogenously. Beginning in 2013, hair and weight loss, as well as general dermatitis, were observed in all individual capybaras (n = 4) in a mixed exhibit at Seoul Zoo. Seven additional vegetables, leafy greens, and fruits that increased dietary vitamin C concentration from ∼300-400 to >600 mg/kg dry matter were added to the diet since January 2015. Within 6 months, capybaras' skin and coats improved considerably, with hair becoming thicker and glossier. Animals visually appeared healthier and gained weight. In conclusion, hair loss, dermatitis, and weight loss in capybara can be improved by feeding enough fresh green leaves, vegetables, and fruits. Although vitamin C is considered a major factor for alleviation of poor body condition observed, increased status of other nutrients (i.e., vitamin B6 ) provided by the diet change may also have contributed to the improvements seen in the capybara. Zoo Biol. 36:50-55, 2017. © 2016 Wiley Periodicals, Inc.

Profile of plasmatic progesterone on pregnancy, and the postpartum estrus of Dasyprocta prymnolopha (Rodentia: Dasyproctidae) / Perfil de la progesterona plasmática durante durante la preñez y celo posparto del Dasyprocta prymnolopha (Rodentia: Dasyproctidae)

Abstract:The agouti (Dasyprocta sp.) is a hystricomorph rodent found in some regions of the Americas. It is an important cynegetic species, which indicates that the overhunting is a threat to their conservation. Very little is known about this wildlife in relation to what already has been studied in domestic animals. Thus, the knowledge on reproduction of wildlife becomes necessary and essential for the management and conservation of these natural resources. Specifically, studies regarding hormonal monitoring are important as a basic tool for research in modern reproductive biotechnology, and currently, there is no information on the progesterone changes during pregnancy of Dasyprocta sp., compared to other hystricomorphs. The aim of this study was to describe the profile of plasmatic progesterone during pregnancy, and report the restart of ovarian cycle in agouti after parturition. For this purpose, 18 black-rumped agoutis (Dasyprocta prymnolopha) born in captivity were used, and one or more consecutive pregnancies were observed. Copulation was confirmed by the presence of spermatozoa observed in the colpocytological examination. Blood samples were collected two times per week, and concentrations of progesterone, assessed in ten agoutis, were determined by radioimmunoassay. The onset of ovarian activity in six females was observed daily by colpocytological examination, starting on the seventh day postpartum. The gestational period observed in this study was 104.04 days (SD = 1.31) (101-106 days) (Number of cases, N = 26), and the interval between births was 126.03 days (SD = 18.40) (109-184 days). The plasmatic profile of progesterone during pregnancy showed a progressive increase from the 1st to the 5th week. The higher progesterone levels over this period (6.88 ng / mL, SD = 3.01) were detected in the 5th week. This value was similar (One-Way ANOVA, p > 0.05) to that observed in the 4th and 6th weeks, but was statistically different (One-Way ANOVA, p < 0.05) when compared to the other weeks. After the 6th week there was a progressive decrease in plasmatic progesterone levels. The animals showed a postpartum estrus of 12.04 days (SD= 4.29) (7-24 days) (N= 23). It was observed that 80.95 % (N= 19) of copulations during this period were fertile. This work contributed to understanding the dynamic changes in the progesterone levels during the pregnancy in agouti. Nevertheless, more studies are needed for a better appreciation of other endocrine and biological changes, in the mother and feto-placental unit of the agouti. Rev. Biol. Trop. 64 (4): 1519-1526. Epub 2016 December 01.

Resumen:El agouti (Dasyprocta sp.) es un roedor histricomorfo encontrado en algunas regiones de América. Es una especie cinegética importante, lo que indica que la caza excesiva es una amenaza para su conservación. Muy poco es lo que se conoce acerca de la biología de los animales silvestres, en relación al conocimiento acumulado sobre los domésticos. Por lo tanto, el estudio sobre la reproducción de los animales silvestres se hace necesario e imprescindible para el manejo y conservación de la especie como recurso natural. En concreto, los estudios relativos a la monitorización hormonal son una herramienta básica para la investigación en biotecnología reproductiva moderna. No hay información sobre los cambios de progesterona durante la preñez de Dasyprocta sp. en comparación con otros histricomorfos. El objetivo de este estudio fue describir el perfil de la progesterona plasmática durante la preñez, y reportar el reinicio del ciclo ovárico después del parto. Para ello, se utilizaron 18 agoutis de rabo negro (Dasyprocta prymnolopha) nacidos en cautiverio. Fueron estudiadas una o más preñeces consecutivas. La copulación fue confirmada por la presencia de espermatozoides observados en examen colpocitológico. Las muestras de sangre se recogieron dos veces por semana, y las concentraciones de progesterona se determinaron en 10 individuos mediante radioinmunoensayo. Se observó el inicio de la actividad ovárica diaria por examen colpocitológico, comenzando en el día séptimo posparto. El período gestacional observado en este estudio fue de 104.04 días (SD= 1.31, rango entre 101-106 días, N= 26), y el intervalo entre los nacimientos fue 126.03 días (SD= 18.40, rango entre 109-184 días). El perfil plasmático de la progesterona durante el embarazo mostró un aumento progresivo de la 1ª a la 5ª semana. Los mayores niveles de progesterona durante este período (6.88 ng / mL, SD= 3.01) se detectaron en la quinta semana. Este valor fue similar (ANOVA de um factor, p > 0.05) al observado en las semanas cuatro y seis, pero fue estadísticamente diferente (ANOVA de um factor, p<0.05) en comparación con las otras semanas. Después de la sexta semana hubo una disminución progresiva en los niveles plasmáticos de progesterona. Los animales mostraron un estro posparto de 12.04 días (SD= 4.29, rango entre 7-24 días, N= 23). Se observó que el 80.95 % (N= 19) de cópulas durante este período fueron fértiles. Este trabajo contribuyó a la comprensión de los cambios dinámicos en los niveles de progesterona durante la preñez del agouti. Sin embargo, se necesitan más estudios para una mejor comprensión de otros cambios biológicos y endocrinos, y en la unidad materna y feto-placentaria del agouti.

Serological evaluation of ovarian steroids of red-rumped agouti (Dasyprocta leporina) during the estrous cycle phases.

The objective of this study was to evaluate serum progesterone (P4) and 17ß estradiol (E2) concentrations throughout the estrous cycle in the red-rumped agouti (Dasyprocta leporina). A total of eight multiparous, captive-bred females were bled throughout their estrous cycle via saphenous venipuncture, with E2 and P4 concentrations being measured via ELISA of the serum collected. Serum E2 ranged from 1212 to 3500pg/ml with a peak value coinciding with observed estrus. However, two additional peak values for E2 were also recorded, one each in metestrus and proestrus respectively. P4 concentrations reached a maximum of 4.23ng/ml, and increases in P4 immediately followed the second E2 peak in metestrus. The highest concentrations of P4 were recorded in mid diestrus; between days 23-25 of the 31-day cycle. This phase was the longest in the agouti, consisting of approximately 19days and accounted for 61% of the cycle. This study increased the basal scientific reproductive knowledge of this potentially valuable neo-tropical species.

Análise histoquímica das glândulas anexas do aparelho reprodutor do macho de paca (Cuniculus paca) / Histochemical analysis of the accessory glands of male paca (Cuniculus paca)

A paca (Cuniculus paca) é um roedor típico de regiões tropicais. Com a finalidade de estudar esta espécie selvagem para manejo adequado e sua preservação, objetivou-se neste trabalho caracterizar a histoquímica das glândulas anexas do trato reprodutor do macho da paca. Para este fim, cortes histológicos dessas glândulas foram submetidas às reações histoquímicas com Ácido Periódico de Schiff (PAS), Alcian blue (AB), PAS. + AB. e PAS + Amilase. Na glândula bulbouretral foi constatado que o epitélio produz secreção rica em glicoproteínas neutras e ácidas, glicosaminoglicanas, e em algumas regiões produz mais de um tipo de secreção. Não foi observada a presença de glicogênio no epitélio. Na glândula vesicular, seu epitélio em borda em escova corou-se por glicoproteínas neutras e também por substância de composição desconhecida, não contendo glicoproteínas ácidas, glicogênio ou glicosaminoglicanas. Verificou-se presença de pequena quantidade de glicoproteínas ácidas e neutras na próstata, em especial na mucosa, além de glicoproteínas ácidas carboxiladas e sulfatadas em pequena quantidade no tecido conjuntivo da lâmina própria dessa glândula. Por fim, a glândula coaguladora apresentou pequena quantidade de glicoproteínas neutras na borda em escova de seu epitélio e substância de composição desconhecida, sendo ausente o glicogênio. Conclui-se que as glândulas anexas do trato reprodutor da paca apresentam características histoquímicas que compartilham certa similaridade com outras espécies da ordem Rodentia, com a presença de glicoproteínas neutras e ácidas em algumas glândulas, principalmente no epitélio da glândula bulbouretal e na borda em escova do epitélio das demais glândulas.(AU)

Paca is a wild rodent typical of the tropical region. In order to study this species with focus on the proper management and preservation, this study aims to characterize the histochemistry of the accessory glands of the reproductive tract of the male paca. For this purpose, histological sections were stained with Periodic Acid-Schiff (PAS), Alcian Blue (AB), PAS + AB e PAS + Amilase. In the histochemical reaction of the bulbouretral gland was found that the epithelium produces secretion rich in neutral and acid glycoproteins, glycosaminoglycans, and in some regions produces more than one type of secretion. The epithelium did not contain any glycogen. In the vesicular gland the epithelium had bush border stained by neutral glycoproteins, but no acid glycoproteins, glycogen or glycosaminoglycan. The coagulating gland showed small amount of neutral glycoproteins in the brush border of the epithelium, without glycogen. It is concludes that the accessory glands of paca have histochemical characteristics that share some similarity with other species of the Order Rodentia, with some glands with neutral and acid glycoproteins, mainly in the epithelium of the bulbouretral gland and in the brush border of the other glands.(AU)

Análise histoquímica das glândulas anexas do aparelho reprodutor do macho de paca (Cuniculus paca) / Histochemical analysis of the accessory glands of male paca (Cuniculus paca)

Paca is a wild rodent typical of the tropical region. In order to study this species with focus on the proper management and preservation, this study aims to characterize the histochemistry of the accessory glands of the reproductive tract of the male paca. For this purpose, histological sections were stained with Periodic Acid-Schiff (PAS), Alcian Blue (AB), PAS + AB e PAS + Amilase. In the histochemical reaction of the bulbouretral gland was found that the epithelium produces secretion rich in neutral and acid glycoproteins, glycosaminoglycans, and in some regions produces more than one type of secretion. The epithelium did not contain any glycogen. In the vesicular gland the epithelium had bush border stained by neutral glycoproteins, but no acid glycoproteins, glycogen or glycosaminoglycan. The coagulating gland showed small amount of neutral glycoproteins in the brush border of the epithelium, without glycogen. It is concludes that the accessory glands of paca have histochemical characteristics that share some similarity with other species of the Order Rodentia, with some glands with neutral and acid glycoproteins, mainly in the epithelium of the bulbouretral gland and in the brush border of the other glands.

A paca (Cuniculus paca) é um roedor típico de regiões tropicais. Com a finalidade de estudar esta espécie selvagem para manejo adequado e sua preservação, objetivou-se neste trabalho caracterizar a histoquímica das glândulas anexas do trato reprodutor do macho da paca. Para este fim, cortes histológicos dessas glândulas foram submetidas às reações histoquímicas com Ácido Periódico de Schiff (PAS), Alcian blue (AB), PAS. + AB. e PAS + Amilase. Na glândula bulbouretral foi constatado que o epitélio produz secreção rica em glicoproteínas neutras e ácidas, glicosaminoglicanas, e em algumas regiões produz mais de um tipo de secreção. Não foi observada a presença de glicogênio no epitélio. Na glândula vesicular, seu epitélio em borda em escova corou-se por glicoproteínas neutras e também por substância de composição desconhecida, não contendo glicoproteínas ácidas, glicogênio ou glicosaminoglicanas. Verificou-se presença de pequena quantidade de glicoproteínas ácidas e neutras na próstata, em especial na mucosa, além de glicoproteínas ácidas carboxiladas e sulfatadas em pequena quantidade no tecido conjuntivo da lâmina própria dessa glândula. Por fim, a glândula coaguladora apresentou pequena quantidade de glicoproteínas neutras na borda em escova de seu epitélio e substância de composição desconhecida, sendo ausente o glicogênio. Conclui-se que as glândulas anexas do trato reprodutor da paca apresentam características histoquímicas que compartilham certa similaridade com outras espécies da ordem Rodentia, com a presença de glicoproteínas neutras e ácidas em algumas glândulas, principalmente no epitélio da glândula bulbouretal e na borda em escova do epitélio das demais glândulas.

Estrutura, ultraestrutura e morfometria da veia cava de paca (Cuniculus paca Linnaeus, 1766) criada em cativeiro / Structure, ultrastructure and morphometry of the Vena cava in the paca (Cuniculus paca Linnaeus, 1766) raised in captivity

A paca (Cuniculus paca) é o segundo maior roedor da fauna brasileira. Apresenta carne de excelente qualidade, o que incentiva a criação comercial. Além disso, este animal pode tornar-se uma opção válida em experimentação embora poucas sejam as informações detalhadas sobre sua morfologia. Assim, objetivou-se descrever a morfologia, morfometria e ultraestrutura de segmentos das porções cranial e caudal da veia cava de quatro pacas (Cuniculus paca) adultas excedentes do plantel do Setor de Animais Silvestres do Departamento de Zootecnia da FCAV-Unesp. Os segmentos venosos foram analisados à microscopia de luz e à microscopia eletrônica de varredura. Foram mensuradas as espessuras do complexo formado pelas túnicas íntima e média, além da túnica adventícia e analisou-se os resultados pela estatística descritiva, teste "T" pareado (p<0,05). Em relação à espessura das túnicas estudadas, comprovou-se que os valores da espessura das túnicas íntima, média e adventícia, para todos os animais, foram significativamente maiores no segmento cranial. As camadas das paredes dos vasos apresentaram variações entre si quanto à estrutura e espessura, supostamente devido a uma adaptação à exigência funcional.

The paca (Cuniculus paca) is the second largest rodent of the Brazilian fauna. The excellent meat quality of this specie encourages the development of their commercial production. Moreover, this animal can become a viable alternative for animal experimentation although there exists scarce detailed information concerning their morphology. Therefore the purpose of this study is to describe the morphology, morphometry and ultrastructure in segments of the cranial and caudal portions of vena cava in four adult males and females of Cuniculus paca from the squad of Wild Animals Sector of Animal Science Department of FCAV-Unesp. Parts of the segments were examined by light microscopy and part by scanning electron microscopy. Thickness measures of the tunica intima and media complex and tunica adventitia of the vena cava were taken and analyzed using "T" test (p<0.05). In vena cava the thickness values of the intima, media and adventitia, for all animals, were significantly higher in the cranial segment. The layers of the vessel walls showed variations in structure and thickness, presumably due to an adaptation to functional demand.

Estrutura, ultraestrutura e morfometria da aorta de paca (Cuniculus paca, Linnaeus, 1766) criada em cativeiro / Structure, ultrastructure and morphometry of the aorta in the paca (Cuniculus paca, Linnaeus, 1766) raised in captivity

Descreveram-se a morfologia, morfometria e ultraestrutura de segmentos das porções torácica e abdominal da aorta de quatro pacas (Cuniculus paca) adultas. Os segmentos aórticos foram analisados à microscopia de luz e à microscopia eletrônica de varredura. Mensuraram-se as espessuras do complexo formado pelas túnicas íntima e média, além da túnica adventícia. Os valores referentes à espessura do complexo formado pelas túnicas íntima e média da aorta torácica cranial foram significativamente maiores (média: 702,19µm) que os valores de outros segmentos aórticos analisados (médias: 354,18µm; 243,55µm). As camadas das paredes do vaso apresentaram variações entre si quanto à estrutura e espessura, supostamente em razão de adaptação à exigência funcional.

The aim of this study was to describe the morphology, morphometry and ultrastructure of segments of thoracic and abdominal aorta portions in four male and female paca (Cuniculus paca). Parts of the segments were examined by light microscopy and part by scanning electron microscopy. Thickness measurements of the tunica intima and media complex and tunica adventitia of the aorta were taken. In all animals the thickness values for the tunica intima and media complex of the cranial thoracic aorta were significantly higher (mean: 702.19µm) when compared to the values of other aortic segments analyzed (means: 354.18µm; 243.55µm). The layers of the vessel walls show variations in structure and thickness, presumably due to an adaptation to functionaldemand.

Os histricomorfos sul-americanos: uma análise comparativa do desenvolvimento embriológico / South-American hystricomorphs: a comparative analysis of embryological development

O objetivo do estudo foi realizar uma análise embriológica dos roedores histricomorfos (paca, cutia, preá e capivara), a fim de comparar com a de outros roedores e com a morfogênese humana um padrão embriológico. Utilizaram-se 8 espécimes de roedores sendo, 2 embriões para cada espécie coletada, ambas em inicio de gestação. Estes foram retirados dos úteros gestantes através de ovariosalpingohisterectomia parcial, seguido de fixação em solução de paraformaldeído 4 por cento. Para as mensurações de Crow-Rump, adotou-se como referência a crista nucal numa extremidade e da última vértebra sacral na extremidade oposta. De forma geral, os embriões analisados mostraram as seguintes características morfológicas: divisão dos arcos branquiais, o não fechamento do neuróporo cranial em alguns embriões estudados, a curvatura cranial acentuada e os somitos delimitados e individualizados. O broto dos membros apresentava-se em desenvolvimento em formato de remo, além da impressão cardíaca e fígado. Na região caudal, visualizou-se a curvatura crânio-caudal, a vesícula óptica com e sem pigmentação da retina, a abertura do tubo neural na região do quarto ventrículo encefálico, a fosseta nasal e a formação das vesículas encefálicas. Concluímos que desenvolvimento embriológico dos roedores histricomorfos pode ser comparado à morfogênese de ratos, cobaios, coelhos e humanos nos diferentes estágios de desenvolvimento, tomando apenas o cuidado com as particularidades de cada espécie, além da implementação de tecnologias reprodutivas, especialmente a de embriões, a qual requer o conhecimento do desenvolvimento pré-implantação referente às fases de desenvolvimento.

The aim of this study was to perform an embryology analysis of South-American hystricomorph rodents (paca, agouti, capybara, and rock cavy) to compare these data with the ones from other rodents and with the human embryologic morphogenesis. We used 8 samples of rodents, 2 embryos for each species, collected during early gestation. The embryos were removed from the pregnant uterus through partial ovarysalpingohysterectomy, followed by fixation in 4 percent paraformaldehyde solution. For crow-rump measurements, we had as reference the nuchal crest at one extremity and the last sacral vertebra on the opposite side. The embryos examined showed the following morphological characteristics: Division of the branchial arches, the cranial neuropore open in some embryos studied, the cranial curvature developed, and the somites delimited and distinct. The hindlimb and forelimb were in development, and showed "row" form; so we found the cardiac impression and the liver region. In the caudal region we observed the head-flow curve, the optic vesicle with and without pigmentation of the retina, the opening of neural tube in the fourth ventricle region of the brain, the nasal cavity, and the encephalic vesicles formation. We conclude that the embryo development of hystricomorph rodents can be compared with the morphogenesis in rats, guinea pigs, rabbits and humans in the early stages of development, being aware of the particularities for each species, in addition to the implementation of reproductive technology, especially of embryos, what requires knowledge of the pre-implantation stages for the different development phases.

Morfologia do útero de cutias nulíparas e não nulíparas / Morphology of the uterus of nulliparous and non nulliparous agoutis

Descreveu-se a morfologia do útero de cutias nulíparas e não nulíparas por meio de ovariossalpingoisterectomia. A análise macroscópica do útero foi realizada in loco e na peça retirada. Segmentos das porções proximal, média e distal do órgão foram colhidas, fixadas e preparadas histologicamente, sendo as amostras analisadas à microscopia de luz, e realizada a histomorfometria das camadas uterinas. Topograficamente, o útero localiza-se na região sublombar, caudalmente aos rins, em continuação aos ovários e às tubas uterinas, estendendo-se até à entrada da pelve, onde se posiciona dorsalmente à bexiga. Caracteriza-se como do tipo duplo, embora culmine em apenas um óstio cervical externo. Microscopicamente, a mucosa uterina é formada por variações do epitélio, de cilíndrico a pseudoestratificado, que se apoia em tecido conjuntivo frouxo, onde se observam glândulas endometriais revestidas por epitélio cilíndrico, além da presença de vasos sanguíneos. A camada muscular subdivide-se em interna ou submucosa, média ou vascular e externa ou subserosa. A camada serosa é composta por tecido conjuntivo e mesotélio. Na histomorfometria, verificou-se que a espessura uterina total e a espessura da camada mucosa, em média, foram maiores nas fêmeas não nulíparas.

The uterine morphology was studied through ovarysalpingohysterectomy in nulliparous and non nulliparous agoutis (Dasyprocta azare). The uterus macroscopic analysis was done "in loco" and in the removed specimens. Fragments of the proximal, media and distal portions of this viscerae were collected, fixed and histologically prepared, and the samples analyzed through light microscopy and through the histomorphometry of the uterine layers. Topographycally, the uterus of this rodent is located on the sub lumbar area, caudally to the kidneys, and following the ovaries and uterine horns, getting through the pelvic entrance, where it is located dorsally to the bladder. It is characterized as a double uterus, although there is only an external cervical os. Microscopically, the uterine mucous is formed by epithelial elevations, from cylindrical to pseudostratified epithelium, which is supported by a loose connective tissue where endometrial glands covered by cylindrical epithelium can be observed, besides blood vessels. The muscle layer is subdivided in inner or submuscous, median or vascular and outer or subserous. The serous layer is composed of a connective tissue and mesothelium. In the histomorphometry analysis, the total uterine thickness and the mucous layer thickness, in average, were bigger on non nulliparous females.

Actividad ovárica del tepezcuintle Agouti paca (Rodentia: Agoutidae) en cautiverio / Ovarian activity of Agouti paca (Rodentia: Agoutidae) under captivity

The ovarian activity of Agouti paca was characterized by hormonal profiles and ovarian structures. Samples of blood were taken from eight females (seven adults and one juvenile) at the breeding grounds of the Facultad de Medicina Veterinaria y Zootecnia in Yucatsn, Mexico. Sampling lasted approximately two months and was done every three and six days. Blood was collected from anesthetized animals, and the levels of progesterone (P4) and 17 beta estradiol (E2) were analized by radioimmunoassay technique. Macroscopic and microscopic analyses were carried out in ovaries of dead animals. The estrous cycle lasted 29+/-8.4 days, levels of 1.61+/-0.65 ng/ml for P4 and 39+/-24 pg/ml for E2 were observed for a follicular phase, 6.18+/-3.70 ng/ml and 29+/-16 pg/ml for P4 and E2 respectively in the luteal phase. Statistically significant differences were found between phases for P4 but not for E2. The presence of extragonadal steroids with levels of P4 of 1.9+/-0.77 ng/ml and E2 of 22+/-17 pg/ml were observed, which are not produced by the effects of managing stress. The changes in the levels of P4 during the cycle are indicators of luteal activity, with the intersticial tissue acting probably as active steroids-producing gland. Follicular growth was observed during the entire cycle.

Se caracterizó la actividad ovárica de A. paca por medio de perfiles hormonales y estructuras ováricas. Se muestrearon ocho hembras (siete adultas y una juvenil) en el criadero de la Facultad de Medicina Veterinaria y Zootecnia en el estado de Yucatán, México, durante aproximadamente dos meses. Se recolectaron muestras sanguíneas cada 3 y 6 días en animales anestesiados. Se estimaron los niveles de progesterona (P4) y 17 beta estradiol (E2) sanguíneos por radioinmunoanálisis. Las estructuras ováricas de animales muertos durante el periodo de muestreo fueron analizadas macro y microscópicamente. El ciclo ovárico duró 29±8.4 días, con niveles de 1.61±0.65 ng/ml para P4 y de 39±24 pg/ml para E2 durante la fase folicular, y de 6.18±3.70 ng/ml y 29±16 pg/ml para P4 y E2 respectivamente, en la fase luteal. Hubo diferencias (p<0.05) en los niveles de P4 entre las fases folicular y luteal, no así para E2. Se detectó la presencia de esteroides extragonadales, con niveles de 1.9±0.77 ng/ ml para P4 y de 22±17 pg/ml para E2, los cuales no son secretados por efecto del estrés por manejo. Los cambios en los niveles de P4 durante el ciclo son indicadores de actividad luteal, funcionando el tejido intersticial probablemente como una glándula productora de esteroides. De igual forma se observó que el crecimiento folicular ocurre durante todo el ciclo.