Table 1.

Molecular and functional characteristics of extracellular vesicles derived from feto-maternal tissues to aid in pregnancy

Source of EVs	Key characteristics			Functions	References
	Size	Markers	Contents
Embryo/embryonic stem cells	50–200 nm	CD9, CD63, ALIX, HLA-G	mRNAs of the pluripotency genes such as Oct4, Sox2, Klf4, c-Myc, Nanog and mi RNAs	Mediates embryo growth Promotes embryo implantation	[17–21]
Oviduct epithelium	30–100 nm, > 100 nm	OVGP1	Total of 315 proteins with varying distribution among the in vivo and in vitro derived EVs	Promotes early embryonic development	[27]
Endometrial epithelial cells	40–150 nm	Tetraspanins, CD9, CD63	254 proteins and 227 miRNAs	Control trophoblast physiology which can promote embryo implantation	[32–34]
Endometrial stromal cells	30–120 nm	Tetraspanin-6, disintegrin, metalloproteinase domain-containing protein 10	250 proteins and several miRNAs including miR-21, miR-126	Control angiogenesis Promote Cell proliferation Crucial role in embryonic and fetal survival	[37–39]
Placenta	50–150 nm	NKGD2 ligands, FasL, TRAIL, syncytin, placental alkaline phosphatase TGF-β	mRNA, miRNA and proteins	Feto-maternal tolerance Pro-inflammatory, anti-angiogenic and procoagulant activity	[41–49]
Endothelial and adipose tissue	150–200 nm	TNF-α, CD63, HSP-TNF-α HPS70 CD63	231 proteins and miRNAs and proteins	Contribute to the systemic inflammation and insulin resistance seen in obese gestational diabetic pregnancies	[50–52]
Microbial (group B Streptococcus)	< 50 nm, 150–300 nm	Unknown	cAMP factor, Hyaluronate lyase, PcsB protein, DNA, RNA	Degradation of amniotic membranes Mechanical weakening resembling preterm premature rupture membrane (PPROM) Fetal death and preterm delivery	[61]