Characteristics of the Equine Placenta at First Trimester

Abstract

The equine placenta is a simple apposition of fetal and maternal tissues, becoming more complex with the formation of microcotyledons around days 75 and 100 of gestation. The present study aimed to describe the gross and microscopic morphology of early equine placenta. Embryonic/fetal membranes from thirty-seven mares were submitted to macroscopic description, light, scanning and transmission microscopy. Overall the gross characteristics of membranes were similar with already described for older stages. However, transmission electron microscopy evidenced high metabolic rate in chorion and allantois, and high secretion profile in amnion and even higher in yolk sac. Gene ontologies enrichment, using published data, pointed several common ontologies in allantoic and amniotic fluids, related to oxygen and iron transport, extracellular space and high-density lipoprotein receptor binding. Overall, the morphological and ontology enrichment could indicate allantois and amnion crosstalk.

The transcriptome landscapes of allantochorion and vitelline-chorion in equine day 30 conceptus

“…AC is the main source of the equine fetal placenta ( Franciolli et al, 2020 ), according to the previous study, its rapid proliferation and increasing interaction with endometrium are promoted by the uterus-derived hepatocyte growth factor-scatter factor (HGF-SF) and epidermal growth factor (EGF) ( Lennard et al, 1998 ; Gerstenberg et al, 1999 ), and in accordance with it, we found AC has high-level expression of EGFR and HGFR. It is known that transforming growth factor-beta (TGF-B) plays an important role in embryo implantation ( Maurya et al, 2013 ), consistently, the TFG-B pathway is significantly enriched in AC.…”

Doppler ultrasonographic measurements of the lateral digital palmar artery in pregnant mares

“…Nonetheless, the placenta reaches full maturity only around day 150 of gestation, and cardiovascular alterations are not described in the first trimester of pregnancy. 49 Consequently, longitudinally following the same group of mares has allowed the identification of significant fluctuations, and T1 values might be considered similar to those of nonpregnant mares.…”

“…Another important limitation was the absence of a control group of nonpregnant mares; the study was conducted on Italian Standardbred horse farms, in which most of the animals were pregnant, and there were not enough nonpregnant mares to enroll in the control group. Nonetheless, the placenta reaches full maturity only around day 150 of gestation, and cardiovascular alterations are not described in the first trimester of pregnancy 49 . Consequently, longitudinally following the same group of mares has allowed the identification of significant fluctuations, and T1 values might be considered similar to those of nonpregnant mares.…”