Stereological analysis of the New Zealand rabbits (Oryctolagus cuniculus) placenta

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.

Key words
decidua; junctional zone; labyrinth; placentation; stereology