Effect of Feed Restriction and Realimentation with Monensin Supplementation on Placental Structure and Ultrastructure in Anglo-Nubian Goats

The aim of this study was to evaluate the effect of feed restriction followed by a realimentation with monensin supplementation on morphological, ultrastructural, and apoptotic characteristics in the term placenta of Anglo-Nubian does. Treatments were a control group ( C = 5 ), a group fed at 0.70 of that consumed by controls ( R = 7 ), and the same as R with monensin ( M = 7 ). After parturition, 27 placentas were gathered, C: 7, M: 10, and R: 10. No differences were detected between treatments in relation to morphological and ultrastructural analysis. The greatest values of binucleate cells were detected in placentas from R, and it could be due to the need to compensate and satisfy nutritional differences of restriction. We detected the highest apoptotic index in R as a consequence of nutritional treatment. We describe for the first time the structural and ultrastructural morphology and remodeling by apoptosis of Anglo-Nubian placenta at term of goats subjected to nutritional restriction during peripubertal period and the use of monensin as a growth promoter. 1. Introduction Caprine placenta is classified as cotyledonary and characterized by the development of restricted areas of interdigitation between fetal and maternal tissues known as placentomes [1]. This placenta has been also classified as synepitheliochorial due to the occurrence of migration of fetal chorionic binucleate cells across the microvillar junction to fuse with the maternal epithelial cells and to form the syncytium [2]. As other ruminants, the goat has a characteristic placental epithelium with two morphologically and functionally distinct cell types in the trophectoderm that are the mononucleate and the binucleate trophoblast cells [3]. Mononucleate cells are the most commonly found in the interface and are primarily involved in the nutrient exchange. Binucleate cells produce hormones, such as placental lactogen and progesterone [3], and through the fusion process with an uterine epithelial cell or with the fetomaternal syncytium release their content to the maternal connective tissue [4]. Binucleate cells are also involved in villi development [4] and are a unique feature in ruminants [5]. In caprines, their role in maturation and delivery of placenta is yet unknown [6]. The placenta is designed to allow an efficient exchange between mother and fetus to optimize the growth and development [7]. Furthermore, a correlation between placental and litter weight has been determined [8, 9]. In turn, the term placental efficiency has been considered as an indicator of uterine capacity,