. 2011 Aug;32(8):539–545. doi: 10.1016/j.placenta.2011.05.001

Table 1.

Comparison of the maternal-fetal interface in humans and mice.

Feature	Human	Mouse
Similarities in placenta type	Discoidal, chorio-allantoic [29]	Discoidal, chorio-allantoic [29]

Haemochorial placentation	Yes	Yes

Decidualised endometrium	Yes, during each menstrual cycle [29]	Yes, triggered by implantation [29]

Disproportionate feto-placental growth	Fetal growth disproportionally higher compared with placental growth in late gestation [29]	Fetal growth disproportionally higher compared with placental growth in late gestation [29]

Syncytial transport and barrier trophoblast	Chorionic villi with syncytiotrophoblast barrier formed by cell fusion. Diploid nuclear DNA content [30].	Labyrinth with syncytiotrophoblast barrier formed by cell fusion. Diploid nuclear DNA content [30]


Invasive trophoblast	Non-proliferative, mononuclear polyploid cytotrophoblast [30]. Invasion of decidua basalis and inner third of the myometrium and differentiation into trophoblast giant cells. EVT face maternal immune system [29].	Non-proliferative, mononuclear polyploid trophoblast with giant cells [30]. Invasion of decidua basalis. Trophoblast giant cells face maternal immune system [29]

Selective MHC class I expression by trophoblast	HLA-C, HLA-G and HLA-E; no HLA-A or HLA-B [12]	H2-K; no H2-D or Qa1 (in C57BL/6 mice [31])

Unique uNK phenotype	CD69⁺ CD117⁺/-KLRG1^high CD56^superbrightCD9⁺CD94^bright[3, 4]	CD69⁺ CD117⁺ KLRG1^high NK1.1-DX5- [32]^a


Activating NKR on uNK cells	NKG2D, NKp46, KIR2DS1 [6, 18]	NKG2D, NKp46, Ly49H, CD16 [32]


Inhibitory NKR on uNK cells	KLRG1, KIR2DL1/2/3, NKG2A [3, 6]	KLRG1, Ly49A, Ly49C, Ly49G2 [31, 32]

Vascular changes concomitant with uNK infiltration of uterus	uNK cells accumulate at site of placentation during the first trimester concentrating around spiral arteries [1]	High degree of uNK cell infiltration at gestational day 9.5 [30] around the spiral artery [7]

Highly polymorphic receptor/ligand systems	KIR on uNK/HLA-C on EVT [18]	Ly49s on uNK/H2-K on trophoblast giant cells [31, 32]

Expression of paternal MHC	Yes [18]	Yes [31]

Impact of paternal MHC on reproductive success	Combination of maternal KIR-AA and fetal HLA-C2 genotypes increases the risk for pre-eclampsia, FGR and RM [15,17,18]	Antigenic disparity between parental H2-linked genes affects transformation of the uterine vasculature, as well as fetal growth and placental efficiency [31]

A different immunophenotype of decidual NK cells in C57BL/6 mice was reported by Mallidi et al., although the cells analysed in this study were mostly DBA- NK1.1⁺[31].