Abstract The onset of gestation is characterized by growth, morphological and functional changes of the placenta. We aim to evaluate the placental compartments in New Zealand rabbits by means of stereological methods. The fetal and maternal portion of placenta (12, 14, 18 and 20 gestational days) was randomly sampled for the stereological analysis. Histological sections were scanned to estimate fetal (labyrinth and junctional) and maternal (decidua) compartment volumes. The total volume of the placenta for the ages of 12, 14, 18 and 20 days was, respectively, 320 mm3, 340 mm3, 940 mm3 and 1300 mm3. The volume of the labyrinth was 56 mm3, 119 mm3, 231 mm3 and 481 mm3, respectively. The volume of junctional zone was 75 mm3, 76 cm3, 238 mm3 and 314 mm3, respectively. The volume of decidua was 174 mm3, 143 mm3, 469 mm3 and 504 mm3, respectively. We concluded that the rabbit´s placenta compartments varied according to the gestational period, increasing continuously over the 20 gestational days. However, on the onset of the development of the placenta the decidua presented faster growth, whereas after the 20 days of development, the labyrinth developed more quickly. This study represents an aid to the understanding of placentation in humans.

Abstract Volumetric muscle loss causes functional weakness and is often treated with muscle grafts or implant of biomaterials. Extracellular matrices, obtained through tissue decellularization, have been widely used as biological biomaterials in tissue engineering. Optimal decellularization method varies among tissues and have significant impact on the quality of the matrix. This study aimed at comparing the efficacy of four protocols, that varied according to the temperature of tissue storage and the sequence of chemical reagents, to decellularize murine skeletal muscles. Tibialis anterior muscles were harvested from rats and were frozen at -20°C or stored at room temperature, followed by decellularization in solutions containing EDTA + Tris, SDS and Triton X-100, applied in different sequences. Samples were analyzed for macroscopic aspects, cell removal, decrease of DNA content, preservation of proteins and three-dimensional structure of the matrices. Processing protocols that started with incubation in SDS solution optimized removal of cells and DNA content and preserved the matrix ultrastructure and composition, compared to those that were initiated with EDTA + Tris. Freezing the samples before decellularization favored cell removal, regardless of the sequence of chemical reagents. Thus, to freeze skeletal muscles and to start decellularization with 1% SDS solution showed the best results.