Expression and localization of estrogen receptor-alpha protein in normal and abnormal term placentae and stimulation of trophoblast differentiation by estradiol

Table 1 Semi-quantitative correlation of placental types with Thy-1 expression, morphology of villous sinusoids and expression of cyclin E low molecular weight variants (cE LMW) for details and quantitative evaluation see Ref. [30], and ERα expression (this study) in normal (NP) and abnormal (AP) basic placental categories and placental types (PT1–PT4).

Basic categories	Placental types	Placental size	Dominant villi	Villous Thy-1	Dilatation of sinusoids	cE LMW variants	ERα protein expression
NP, ERα+	PT1^a	Normal	mature	high	low	all low	strong
	PT2^b	Normal	mature	moderate	moderate	all higher vs. PT1	strong
AP, ERα-	PT3^c	Normal	aged	low	excessive	some higher	traces
	PT4A^d	Hypertrophy	young	traces	low	some higher	traces
	PT4B^e	Atrophy	immature	traces	low	some higher	traces

^aPT1, normal placental type, with occasional development of new mature villi or expansion of existing villi to fulfill the demands of the progressively growing fetus. Rarely, if there is no requirement for villous replacement or expansion, the ERα might not be expressed. ^bPT2, marginal irregularity, which can be interpreted as a compensation of imminent placental aging by enhanced development of new villi associated with expansion of existing mature villi and moderate dilatation of villous sinusoids. ^cPT3, placental senescence associated with the extreme dilatation of villous blood sinusoids and no compensatory villous development or expansion. ^dPT4A, placental hypertrophy – terminal villi persist in a young/immature state with compensatory development of additional young terminal villi (maternal diabetes mellitus associated with fetal macrosomia). ^ePT4B, placental atrophy – terminal villi persist in a young/immature state without compensatory development of additional young terminal villi (intrauterine growth retardation and poor Apgars).

ISSN: 1477-7827