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The aortic valve was investigated in 58 sheep and 60 swine without heart disease.After fixation in 4% formalin, the distance between the ostia and the elements of the right/left aortic sinuses was measured. For the left coronary ostium (LCO), it was found that in sheep 81% were below and 19% at the level of intercomissural line (IL). In pigs, 88.3% were below and 11.7% at the IL level. In sheep, the OCL was close to the right valve commissure (CVR) in 98.3% and close to the left valve commissure (CVV) in 1.7%. In pigs, it was close to RVC at 83.3% and close to LVC at 16.7%. Regarding to RCO, it was found that in sheep 69% was below, 1.7% was above and 29.3% at the IL level. In pigs, 20% were below, 15% above and 65% at the IL level. The distance of the RCO in relation to the valve commissures was 56.9% close to LVC and 43.1% close to RVC in sheep. In pigs, 81.7% were close to LVC and 18.3% close to RVC. The position of LCO was balanced between sheep and swine, while the RCO in swine was closer to CVE when compared with sheep. The accessory coronary ostium was observed in 18.6% of sheep and 10% of pigs. Thus, it is concluded that in sheep and swine the left coronary artery is perfused only in ventricular diastole. Perfusion of the right coronary artery occurs more frequently in diastole and less frequently in ventricular systole.

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A placenta possui sistemas vasculares essenciais e intimamente associados. A sua efetividade está relacionada ao tipo de fluxo sanguíneo entre as circulações materno e fetal e assim com a morfologia da vascularização. Esta pesquisa teve como objetivo, estudar os aspectos anatômicos da vascularização macro e microscópica da placenta de ovinos, mestiços das raças Corriedale e Ideal, que vivem próximos do nível do mar e a sistematização dos vasos fetais desde o funículo umbilical até o leito capilar. Os cotilédones dos ovinos são esferóides na sua maioria e recebem de um a quatro ramos vasculares em sua concavidade central. Anastomoses dos vasos do funículo umbilical ocorrem somente entre artérias. Entre os ramos dos vasos coriônicos, as anastomoses são mais freqüentes em veias do que nas artérias. Foram encontrados 187 tipos de arranjos arteriocotiledonários diferentes. A artéria coriônica dirigida ao corno gestante possui um trajeto mais curto e emite menos ramos cotiledonários que a do corno não gestante. A veia coriônica é formada pela confluência de dois ramos e recebe confluentes colaterais que freqüentemente se anastomosam entre si. A microvascularização do cotilédone fetal foi estudada em microscopia eletrônica de varredura e está representada pela presença de árvores vilosas cônicas e com relato de alças capilares em forma de leque. As características microscópicas da placenta refletemas características do desenvolvimento viloso placentário determinada pela altitude na qual os animais vivem (a 95 m do nível do mar).

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The present study describes the embryonic and fetal development of the central nervous system in rabbits from the seventh day after conception until the end of the full-term fetal period. A total of 19 embryonic and fetal samples were carefully dissected and microscopically analyzed. Neural tube closure was observed between 7.5 and 8 days of gestation. Primordial encephalic vesicle differentiation and spinal canal delimitation were observed on the 12th day of gestation. Histologically, on the 15th day of gestation, the brain, cerebellum, and brain stem were delimited. On the 18th day of gestation, the cervical and lumbar intumescences of the spinal cord were visible. On the 28th day of gestation, four-cell layers could be distinguished in the cerebral cortex, while the cerebellar cortex was still differentiating. Overall, the morphological aspects of the embryonic and fetal developmental phases in rabbits were highly similar to those in humans. Thus, the present study provides relevant information highlighting rabbits as an excellent candidate animal model for preclinical research on human neurological diseases given the high adaptability of rabbits to bioterium conditions and the similarity of morphological events between rabbits and humans.

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