Sexual dimorphism in placental development and function: Comparative physiology with an emphasis on the pig

Abstract

Across mammalian species, it has been demonstrated that sex influences birth weight, with males being heavier than females; a characteristic that can be observed from early gestation. Male piglets are more likely to be stillborn and have greater preweaning mortality than their female littermates, despite the additional maternal investment into male fetal growth. Given the conserved nature of the genome between the sexes, it is hypothesized that these developmental differences between males and females are most likely orchestrated by differential placental adaptation. This review summarizes the current understanding of fetal sex‐specific differences in placental and endometrial structure and function, with an emphasis on pathways found to be differentially regulated in the pig including angiogenesis, apoptosis, and proliferation. Given the importance of piglet sex in agricultural enterprises, and the potential for skewed litter sex ratios, it is imperative to improve understanding of the relationship between fetal sex and molecular signaling in both the placenta and endometria across gestation.

Uterine dynamics, blood profiles, and electronic fetal monitoring of primiparous and multiparous bitches classified according to their weight

“…The relationship between higher birth weight and male sex is observed in different mammal species. This is attributed to sexual dimorphism, as males tend to be larger than females, as reported in newborn piglets ( 76 ). Moreover, as previously discussed, the body weight of the bitches also influences the birth weight of the newborns.…”

Effects of foetal size, sex and developmental stage on adaptive transcriptional responses of skeletal muscle to intrauterine growth restriction in pigs

“…Limited knowledge is available on the molecular mechanisms driving altered skeletal muscle development in growth-restricted pigs, with only a few studies focusing on early developmental events 24,25 . Moreover, the effects of foetal sex have often been overlooked in previous large animal studies, and must be included to fully understand the mechanisms involved in developmental programming 26,27 . Building on the results of previous www.nature.com/scientificreports/ transcriptome-wide profiling in late-stage pig foetuses 12,23 , the present study reports on the expression dynamics of different transcripts involved in key aspects of the adaptive response of foetal muscle to IUGR.…”