Menorrhagia affects approximately 15% of all women, often without identifia
ble cause. Endometrial spiral arterioles are believed to play a major role
in controlling menstruation, and are a major site of menstrual loss. We pos
tulate that, alterations in the growth and, development of spiral arteriole
s, particularly the vascular smooth muscle cells (VSMC), may contribute to
menorrhagia, We examined VSMC proliferation around endometrial arterioles i
n central and menorrhagic tissues and the possible roles of transforming gr
owth factor beta (TGF-beta) and endothelin in this process. Proliferating V
SMC were located immunohistochemically, then evaluated using computer-aided
image analysis. VSMC proliferation was low and constant during the early s
tages of the menstrual cycle, increasing; at the mid to late secretory stag
es (P < 0.002), Menorrhagic women had significantly reduced VSMC proliferat
ion in their spiral arterioles at the mid and late secretory stages (P < 0.
02), VSMC around straight arterioles proliferated at similar rates across t
he cycle, apart from a significant decrease in VSMC proliferation in menorr
hagic women at the late secretary stage (P < 0.002). Endothelin concentrati
ons decreased significantly in the epithelium of menorrhagic women (P = 0.0
5), while TGF-beta demonstrated no significant differences in the mid to la
te secretory tissues studied. The results indicate a significant functional
difference between the spiral arterioles of control and menorrhagic women
that may play a role in menorrhagia, while leaving the roles of endothelin
and TGF-beta undetermined.