Km. Abberton et al., Smooth muscle alpha actin and myosin heavy chain expression in the vascular smooth muscle cells surrounding human endometrial arterioles, HUM REPR, 14(12), 1999, pp. 3095-3100
Endometrial spiral arterioles are believed to play a major role in controll
ing menstruation. These arterioles coil and grow through the secretory stag
es of the cycle, unlike the 'straight' endometrial arterioles that remain u
ncoiled, We postulate that alterations in the growth and development of spi
ral arterioles, in particular the vascular smooth muscle cells (VSMC), may
contribute to menorrhagia. We examined smooth muscle alpha actin (alpha SMA
) and myosin heavy chains (MHC), two VSMC differentiation markers, in the e
ndometrial arterioles of 64 women, comparing them in controls, menorrhagic
tissues and across the menstrual cycle. aSMA and MHC expression were determ
ined immunohistochemically then evaluated using computer-aided image analys
is. alpha SMA expression in the straight arterioles of menorrhagic women wa
s reduced in the early secretory stage of the cycle and significantly decre
ased at the mid-secretory stage of the cycle (0.67 +/- 0.03 versus 0.55 +/-
0.04, P less than or equal to 0.05), No other significant differences were
observed in aSMA and MHC expression in straight arterioles, MHC expression
was significantly reduced in the spiral arterioles of menorrhagic tissues
at the early secretory stage (0.57 +/- 0.01 versus 0.38 +/- 0.04, P less th
an or equal to 0.05), Our results demonstrate differences in the VSMC of me
norrhagic women compared with controls, with delayed MNC expression in the
spiral arterioles and reduced alpha SMA expression in straight arterioles d
uring the mid-secretory stage of the cycle.