Figure 1.
Anatomy of the mouse female reproductive tract.
The diagram shows the regions at which the corresponding sections, labeled with smooth muscle α-actin conjugated to Cy3, were obtained (1 – vagina, 2 – cervix with surrounding vaginal tissue, 3 – uterine body, 4 – uterine horn). The uterine body and horn present a denser and wider muscle layer than the cervix and vagina.
Figure 2.
Tension recordings from cervical and vaginal strips of smooth muscle held at 5 mN resting tension in PSS with uterine data obtained from longitudinal muscle strips presented for comparative purposes.
Non-pregnant (A) and late pregnant (D) mice uteri exhibited spontaneous contractions. The cervices from non-pregnant mice (B) exhibited spontaneous contractions in estrus and metestrus, but not diestrus and proestrus (see figure 3 for more details); while cervices from pregnant mice (E) always exhibited spontaneous contractions. Vaginal tissues from non-pregnant (C) and pregnant (F) mice were generally not spontaneously active.
Figure 3.
The effect of the oestrus cycle and late pregnancy on uterine and cervical spontaneous activity.
A& C, Frequency of uterine and cervical contractions (per 5 min), indicating that the uterus is spontaneously active throughout the oestrus cycle and the cervix is spontaneously active in estrus, metestrus and in pregnant mice; * mean frequency of cervices from pregnant mice is slightly higher than estrus and metestrus (* P<0.05). This difference is small and has not been further investigated. B & D, the force of uterine and cervical contractions in the different stages of the oestrus cycle and in pregnancy. While significant (* P<0.05), the difference in contraction strength for uterine tisues at proestrus has not been further investigated. Data is presented as the mean ± SE with n = 4–9.
Figure 4.
Contractile responses recorded in response to the potassium channel blocker tetraethylammonium chloride (TEA) or an agonist (oxytocin) on cervical and vaginal smooth muscle with uterine data presented for comparative purposes.
Application of TEA (10 mM) enhanced spontaneous contractions in uterine (A) and cervical (B) tissues and caused vaginal (C) and cervical tissues in diestrus and proestrus (data not shown) to become spontaneously active. Application of oxytocin (1 nM) to uterine (D), cervical (E) and vaginal (F) tissues caused a large contraction that gradually decreased revealing spontaneous contractions at high frequency for all three tissues.
Figure 5.
Expression of c-Kit or vimentin immunoreactivity in the reproductive tract.
Single confocal optical sections taken from wholemount preparations. As previously reported (Duquette et al., 2005) c-Kit or vimentin immunoreactive cells are present in the myometrium (white arrows) (B & F). However these were rarely observed in the cervix (C & G) and not observed in the vagina (D & H). Studies made for comparative purposes under the same conditions show the well reported extensive network of ICCs (white arrows) present in the stomach (A & E). Scale bar = 100µm.
Figure 6.
Spontaneous contractions occur in the presence of CPA, an inhibitor of SR Ca2+ stores.
Shown are the effects of inhibiting the SERCA using 10 µM CPA on contractions in uterine (A, A1), cervical (B, B1) and vaginal (C, C1) smooth muscle strips from non-prenant and pregnant mice. Recordings from vaginal tissues were made in the presence of TEA (10 mM) to reveal contractions. CPA (10 µM) applied for at least 30 minutes modulated but did not abolish the contractions in any of the three tissue types.