Estudo microscópico e macroscópico, com enfoque radiográfico e de alizarina, no desenvolvimento embrionário e fetal de gatos domésticos (Felis catus) em diferentes idades gestacionais

Central nervous system development of cats (Felis catus L. 1758)

The morphological similarities of vertebrates' embryonic development are used as a criterion for choosing animal models that can be used in biomedical research. This study describes the embryonic and fetal development of the domestic cat's central nervous system from 15 days after conception until birth. In total, fifty-seven samples of embryos and fetuses were carefully dissected and analyzed microscopically. The closure of the neural tube was observed between 14-15th days of gestation. The differentiation of the primordial cerebral vesicles was observed from the 17th day of gestation. On the 19th day of gestation, the formation of the choroid plexus began, and on the 20th day of gestation, the brain and brainstem were well-identified macroscopically. On the 24th day of gestation, four layers of cells from the cerebral cortex were described, and on the 60th day, six layers of cells were present. The cerebellar cortex had the three classic cortical layers at this stage. The morphological aspects of embryonic and fetal development in cats were very similar to the stages of development of the human nervous system. As such, this study provided relevant information that highlights the domestic cat as an animal model option for preclinical research on infectious and non-infectious neurological diseases in humans.

Stereological analysis of metanephros from domestic cat (Felis catus, Linnaeus 1798) embryos and fetus

Kidney diseases are the most common illness for cats with a prevalence seven times higher than in dogs. Metanephros is the last of three renal systems to be formed during the embryonic period, which then becomes the permanent kidney. The current work aimed to analyse the morphology and to quantify the structures present in the development of metanephros from domestic cat (Felis catus) embryos and foetuses. For this purpose, the evaluation of the biometric parameters of metanephros from cat embryos and foetuses was performed in addition to the quantification of renal corpuscles and volume of cortical and medullary layers by stereological analysis. The evaluated biometric parameters were weight, width, height, thickness and volume. The values of the measured biometric parameters increased throughout the gestational stages. The quantity of renal corpuscles gradually increased following the embryo-foetal development, mainly during the middle of the gestational stage. It was during this phase that morphologically, a complete corticomedullary division was observed. Although the difference in the quantity of renal corpuscles between the middle and the end of the gestational stages was not statistically significant, there was an increase in the volume of the medullary layer and a decrease in the volume of the cortical layer between these two stages. These findings suggest that the metanephros presents a progressive growth with the renal corpuscles following this development until the middle of the gestational stage. Starting from this phase, the differentiation of the corticomedullary layers can be seen with a significant increase in the medullary layer.

Development of urinary organs in domestic cat during the embryonic and fetal periods

The embryonic origin of the urogenital system came from the intermediate mesoderm. Kidney development involves three successive renal systems with a fast chronological overlap: the pronephro, the mesonephro, and the metanephro. Due to the lack of specific knowledge about this system in cats the present work aimed to describe their urinary organs development, focusing on the structures seen in pronephro, mesonephro, and metanephro during the embryonic and fetal stages of development. The techniques used in this study were: light microscopy, immunohistochemistry, scanning electron microscopy, and transmission electron microscopy. For that, embryos and fetuses from 12 pregnant mixed-breed domestic cats in different gestational stages were used to describe the proposed organs. The pronephro is present at early stages of embryonary development in embryos from 15 to 19 days with the presence of pronephro's corpuscles, ducts and tubules. The mesonephro is found, in general, between days 17 and 37, and contains mesonephric ducts, mesonephric tubules, and glomeruli. The metanephro is seen since 21 days of pregnancy with the presence of glomeruli, proximal and distal contorted tubules and at day 37, the cortex-medullary region is already differentiated. The evaluation of these structures enhances the knowledge about embryology of the urinary system in cats, aiding a better anatomical understanding of the system in the specie allowing the correlation with other species.

Comparative Development of Embryonic Age by Organogenesis in Domestic Dogs and Cats

The precise determination of the embryonic chronology is very important in reproductive biotechnologies, especially in estimating embryonic age. Thus, there is a need for greater knowledge and standardization for determining the chronology of embryonic development and functional morphology. We describe aspects of embryonic development in two domestic carnivores to add knowledge about organ peculiarities and for application in veterinary practice, in prenatal development and in the biotechnology fields. We found that the development of differential characteristics of embryonic organs occurs in the first trimester of pregnancy for both species. Thus, using the combination of the crown-rump length, macroscopic analysis and optical microscopy, it is possible to predict gestational age more precisely in animals that lack a defined breed and establish an embryonic pattern.

An opportunity for testing multiple paternity in a wild Jaguar (Panthera onca)

We performed a paternity test for three cubs from one wild female jaguar (Panthera onca). The opportunity for this study was generated by an accident involving a vehicle collision with a pregnant jaguar in the central Amazon. The cubs are polyzygotic triplets and were found to have been sired by the same male. Here, we also provide an overview and discuss several aspects of jaguar reproduction.