Marina Bonatelli

Placentation in the paca (Agouti paca L)

BackgroundThe paca is a South American rodent with potential as a commercial food animal. We examined paca placenta as part of a wider effort to understand the reproductive biology of this species.MethodsThirteen specimens between midgestation and term of pregnancy were studied by light and transmission electron microscopy.ResultsThe placenta is divided into several lobes separated by interlobular trophoblast. Maternal arterial channels and fetal veins are found at the centre of each lobe. In the labyrinth, maternal blood flows through trophoblast-lined lacunae in close proximity to the fetal capillaries. The interhaemal barrier is of the haemomonochorial type with a single layer of syncytiotrophoblast. Caveolae occur in the apical membrane of the syncytiotrophoblast and recesses in the basal membrane, but there is no evidence of transtrophoblastic channels. The interlobular areas consist of cords of syncytiotrophoblast defining maternal blood channels that drain the labyrinth. Yolk sac endoderm covers much of the fetal surface of the placenta. The subplacenta comprises cytotrophoblast and syncytiotrophoblast. There are dilated intercellular spaces between the cytotrophoblasts and lacunae lined by syncytiotrophoblast. In the junctional zone between subplacenta and decidua, there are nests of multinucleated giant cells with vacuolated cytoplasm. The entire placenta rests on a pedicle of maternal tissue. An inverted yolk sac placenta is also present. The presence of small vesicles and tubules in the apical membrane of the yolk sac endoderm and larger vesicles in the supranuclear region suggest that the yolk sac placenta participates in maternal-fetal transfer of protein.ConclusionThe paca placenta closely resembles that of other hystricomorph rodents. The lobulated structure allows for a larger exchange area and the development of precocial young.

Development of the Inverted Visceral Yolk Sac in Three Species of Caviids (Rodentia, Caviomorpha, Caviidae)

Guinea pig related rodents possess numerous derived placental characters. We attempt to identify diversity within the visceral yolk sac and its association with the chorioallantoic placenta in three species of caviids, two of them possessing a capsule formed by the decidua that covers the chorioallantoic placenta. The results verify that in early pregnancy all three species have an inverted yolk sac placenta. In advanced pregnancy the species differ: Galea spixii, as representative without a capsule, bear a yolk sac in apposition to the chorioallantoic placenta with signs of exchange activity until term. Galea is similar to other caviomorphs in this respect. In Dasyprocta leporina and Cuniculus paca, the representatives possessing a capsule, the yolk sac endoderm lacks signs of substance exchange. Evidently, the presence of a capsule prevents such an interaction. The variations established here must be considered if animal models for human placentation are required which have restricted access to the chorioallantoic placenta from the outside.

Placentation in dolphins from the Amazon River Basin: the Boto, Inia geoffrensis, and the Tucuxi, Sotalia fluviatilis

A recent reassessment of the phylogenetic affinities of cetaceans makes it timely to compare their placentation with that of the artiodactyls. We studied the placentae of two sympatric species of dolphin from the Amazon River Basin, representing two distinct families. The umbilical cord branched to supply a bilobed allantoic sac. Small blood vessels and smooth muscle bundles were found within the stroma of the cord. Foci of squamous metaplasia occurred in the allanto-amnion and allantochorion. The interhemal membrane of the placenta was of the epitheliochorial type. Two different types of trophoblastic epithelium were seen. Most was of the simple columnar type and indented by fetal capillaries. However, there were also areolar regions with tall columnar trophoblast and these were more sparsely supplied with capillaries. The endometrium was well vascularised and richly supplied with actively secreting glands. These findings are consistent with the current view that Cetacea are nested within Artiodactyla as sister group to the hippopotamids.

Fissura placentária de gatas SRD, Felis catus - Linnaeus, 1758: aspectos macro e microscópicos

This research consists of study of shematic macroscopy cats placenta and placental characterization as its type, zonary placenta, that 62,5% of cases presents a fissure at distal area of umbilical cord. This is formed by a joustfetal area, joustplacental area and middle area, histological findings: two arteries, a vein, two vitelline pedicule and two allantois pedicule. In the fissure, an allantoic epithelium covering this area at 10% of the cases and 90% found a trophoblast decrease compared with others placental areas out of the fissure. So, the feline placenta, in its maternal/fetal relationship shows a imcomplete zonary placenta, different of that occurs in other carnivores.

Análise morfológica da placenta da paca (Agouti paca, Linnaeus, 1766: Estudo ao microscópio de luz e à microscopia eletrônica de transmissão

Morphological aspects of the placenta of paca (Agouti paca, L., 1766) were studied by means of analysis with light microscopy and transmission electron microscopy of tissue samples corresponding to the portion of greatest placental connection of nine placentas in different pregnant females, in intermediary and final phases of pregnancy. We performed this study because there was, associated with the necessity of searching new specimen that might act as fine experimental models, the availability of this rodent in our environment. In the other hand, an improved knowledge of the reproductive aspects of these animals offers subsidizes to the establishment of rational raising centers of this species, since its preservation is necessary, besides the big commercial interest on its meat. The results showed that this rodent presents one vitelline and one chorio-allantoic placenta, which is a hemochorial and labyrinthine organ, histologically composed by lobules divided into three different portions: lobule center, labyrinth, and interlobule. In the lobule center portion the presence of arteries and veins was noticed, and in its peripheral portion there were two tubular systems set in a parallel way, where blood lacunas and capillaries were in close contact, constituting the labyrinth portion. Arteries and veins composed the interlobule. The main component of the placenta was the trophoblast, which independently from its site, presented a syncytio origin. Regarding the ultrastructure, the placenta barrier of paca was classified as hemomonochorial.

Glândula mamária do mocó (Kerodon rupestris - Wied Neuwied, 1820): aspectos morfológicos

Procurando colaborar com a exploracao zootecnica racional dos mocos (Kerodon rupestris) foi descrita a morfologia da glândula mamaria destes roedores, que por sua vez podem tornar-se uma fonte de alimento para populacao nordestina. Foram utilizados cinco animais cedidos pelo Centro de Multiplicacao de Animais Silvestres (CEMAS) da pela Escola Superior de Agricultura de Mossoro (ESAM) registrado junto ao IBAMA como criadouro cientifico sob o numero 12.492-0004. As glândulas mamarias foram retiradas atraves de dissecacao e foram fotografadas. Cada animal apresentou duas glândulas mamarias localizadas na regiao inguinal. Histologicamente a glândula mamaria era composta por uma grande quantidade de lobulos, repletos de glândulas tubulos-alveolares com epitelio simples cubico. Na papila mamaria fibras musculares apresentaram-se dispostas de modo circular, o que possivelmente auxilia na contracao para excrecao do leite.

Vascularização arterial e estrutura das tubas uterinas em caprinos sem raça definida

Thirty sets of genital organs from adult goats were collected in specialized slaughter houses. Two procedures were utilized in this experiment: 1) injection of red dyed neoprene latex 450 followed by fixation in a 10% formaldehyde water solution; 2) injection of cinabrium dyed gelatin followed by a diafanization process using the method of Spalteholz. It was observed that the vessels responsible for the blood irrigation of the womb tubes come from the ovarian arteries. The ovarian arteries in all samples had their origin in abdominal aortas varying only in their position, uterine, lateral or uterine lateral. Besides being responsible for the blood irrigation of the ovaries, the ovarian arteries also created branches to the womb. The womb tube divides into a mid tube artery, which irrigates the mid portions of the tubes and into a stream tube artery, which is responsible for the irrigation of the caudal portion of the womb tube and the extremity of the uterus. It also irrigates the skull tube artery, that originates from the womb tube artery and arterially supplies the skull portions of the womb tubes. Histologically, all the segments of the tubes (isthmus, phial and inphundibulum) showed a simple, cylindrical, ciliated epithelium and were also constituted by the mucous and the muscular layers by a serous membrane.

Estudo anatômico das artérias e veias do funículo umbilical, sua ramificação e disposição na placenta de gatos (Felis cattus, Linnaeus, 1758)

A pesquisa consta de estudo macroscopico do sistema arterial e venoso do funiculo umbilical e da placenta de fetos de gato e caracterizacao placentaria quanto ao tipo, zonaria que em 62,5% dos casos apresenta uma fissura em regiao distal ao funiculo umbilical. O funiculo e formado por uma porcao justafetal, uma porcao justaplacentaria e um terco medio, encontrando-se: duas arterias umbilicais, uma veia umbilical, dois pediculos vitelineos e dois pediculos alantoideos.