Abstract Extracellular vesicles (EVs) derived from stem cells (SCs) have regenerative potential and the possibility of being used in treating chronic diseases. EVs present lower risk of tumorigenicity and easily to isolation and storage. Therefore, this research aims to compare the morphological characteristics of the EVs (up to 150nm) derived from stem cells obtained from canine amniotic membranes in different passages during the in vitro culture. For this, cells from the amniotic membranes were isolated, cultured, and characterized. In order to answer our aim, the number of cells was normalized at each passage to generate conditioned media for EVs separation. The cells were differentiated into adipogenic, chondrogenic, and osteogenic tissue, to characterize these cells as mesenchymal stem cells (MSC). Moreover, flow cytometry analysis was performed and showed that the MSC were positive for CD90, CD105 and negative for CD34, CD45, mesenchymal and hematopoietic markers, respectively. For EVs analysis, MSC in different passages (P0-P2) were culture until 80% of confluence, then the medium was replaced by EVs depleted medium. After 48h, culture medium was collected and centrifuged to separate EVs, followed by nanoparticle tracking analysis. The EVs were also characterized by western blot and transmission electron microscopy (TEM). EVs were positive for Alix and negative for Cytochrome C as well as presented the traditional cup-shape by transmission electronic microscopy. Our results demonstrated that the concentration in the different passages was increased in P0 compared to P1 and P2 (p<0.05). No differences were found in EVs size (P0=132nm, P1=130nm and P2=120nm). Together, these results demonstrate that P0 of MSC is enriched of EVs when compared to later passages, suggesting that this passage would be the best to be applied in pre-clinical tests. Despite that, more studies are necessary to identify the EVs content and how the cells will respond to treatment with them.

Abstract The Ocelot (Leopardus pardalis) is the largest species of this genus, despite having broad distribution in the Americas; it is included in the main list of endangered species. Their conservation is widely studied, but there is a lack of studies about their morphology. In order to contribute to the knowledge of its reproductive system, five male and female ocelots were examined macro- and microscopically by histological techniques. Macroscopic analysis of the male reproductive system revealed presence of prostate and bulbourethral gland located caudally to the urinary bladder and a penis with small spicules. Microscopically, the testes were encased by the tunica albuginea and divided it into lobules with 5-10 tubules per lobe. In females, macroscopic analysis demonstrated two ovaries position dorsally in the sublumbar region and caudal to the kidneys. The bicornuate uterus is composed by uterine horns (12 to 14 cm in length), which travels from the ovaries in a caudal direction to form a small uterine body (4 cm in length). The ovary analysis revealed, in longitudinal section, medullary region composed of loose connective tissue, a stroma rich in blood vessels, and an external parenchymal region surrounded by a tunica albuginea. The results of the study confirmed the similarity between ocelot's reproductive system as domestic cat's ones and showing for the first time the complete morphological tool to highlight these organs and tissue in this male and female endangered wild felid specie. The present study open venue for other researchers to consider morphological and preservationist features and aimed to help at long-term conservation of wild felines.

Abstract The immune system is mainly responsible for protecting the organism against agents that may interfere in its homeostasis. Thus, understand how this system develops and operates is very important, for create new therapies to assist this system in its operation, such as its failure. In domestic dogs, few studies show how actually occurs the development, maturation and functioning of the immune system. Therefore, this study demonstrates the development and possible activation of it on dog fetus from late gestational period by in situ and microscopic analyzes.

Resumo: A formalização é a principal forma de conservação de corpos e peças anatômicas, devido principalmente ao seu baixo custo. A técnica baseia-se na utilização do formaldeído (5-20%) como fixador e conservador. Entretanto existem vários fatores negativos à sua utilização, como odor desagradável, escurecimento, aumento de peso e rigidez das peças e sérios problemas ambientais quando descartada de forma incorreta, além de ser um produto classificado pela Agência Internacional de Pesquisas em Câncer como altamente cancerígeno. Existem várias opções para substituir o formaldeído, a glicerinação é uma delas, cujo será tratada neste trabalho. A glicerina atua como antifúngico e bactericida, além de ter muitas vantagens em relação ao formol, tratando-se de odor, textura e coloração, além de não ser prejudicial a saúde. Porém o seu custo ainda é elevado e isso explica sua pouca utilização em laboratórios de anatomia. Este trabalho tem como objetivo mostrar as vantagens do uso da glicerina em relação ao formol e propor uma possível substituição deste produto cancerígeno para preservar a saúde dos alunos, funcionários e professores dentro do laboratório, além de permitir um ambiente mais agradável para o aprendizado.

Abstract: The formalization is the main form of body and anatomic conservation, mainly due to its low cost. The technique is based on the use of formaldehyde (5-20%) as fixative and preservative. However there are several negative factors on their use, unpleasant smell, browning, weight gain and stiffness of parts and serious environmental problems if disposed of incorrectly, and is a product classified by the International Agency for Research on Cancer as highly carcinogenic. There are several options to replace formaldehyde and glicerinação is one of them, whose which will be treated in this work. Glycerin dehydrates the cell and acts as antifungal and antibacterial, and has many advantages compared to formaldehyde. But its cost is still high and this explains their limited use in the anatomy lab. This work aims to show the advantages of using glycerin in relation to formaldehyde and propose a possible replacement of this carcinogen to preserve the health of students, staff and teachers within the laboratory, and allows a more pleasant environment for learning.