Changes in the physical properties of the uterine cervix of the rat during pregnancy

The effects of oestradiol benzoate, progesterone, relaxin and ovariectomy on cervical extensibility in the late pregnant rat

“…The increases observed in untreated pregnant rats in the present results confirm the observations of Harkness & Nightingale (1962) and Rundgren (1974). The cervix of the late pregnant rat contains smooth muscle which is capable of responding to prostaglandins, oxytocin and neurotransmitters, but on Day 22 maximal responses of spirally cut cervical strips were small relative to those of the uterine horn (Hollingsworth & Isherwood, 1978, 1979, perhaps due to the lower proportion of smooth muscle in the cervix (Harkness & Harkness, 1959). It is therefore reasonable to account for changes in the extensibility of the cervix mainly in terms of changes in the connective tissue.…”

“…The cervix was defined as the less vascular tissue with parallel lumina be¬ tween the uterine horns and the vagina (Harkness & Harkness, 1959;Hollingsworth & Isherwood, 1978). Weight of total products of conception (fetuses, placentas, amniotic fluid and membranes), and numbers of alive and dead fetuses per litter were routinely determined.…”

“…Tensile properties of the isolated cervix were measured by a modification (Hollingsworth & Isherwood, 1977) of the method of Harkness & Harkness (1959) and Harkness & Nightingale (1962). Briefly, the cervix was mounted in a tissue bath containing Krebs-Henseleit (1932) K/l0 (min-1), which is the fractional increase in circumference per min.…”

“…The properties of the rat cervix show two distinct changes during pregnancy. There are increases in both the inner circumference of the cervix (associated with increased tissue mass) and its extensibility or ability to extend continuously under prolonged loading (Harkness & Harkness, 1959; Harkness & Nightingale, 1962;Rundgren, 1974). In the rat both properties increase progressively from about Day 12 until the end of pregnancy.…”

Alterações morfológicas e na contagem de fibras colágenas induzidas pela hialuronidase no colo de ratas prenhes

“…Há décadas a rata vem sendo estudada por suas características bioquímicas, biomecânicas e avaliação das alterações histológicas na cérvice uterina ao longo da gestação, prestando-se adequadamente para esse tipo de investigação 18,19 . Obviamente, o experimento permitiu a obtenção de material histológico do grupo controle, o que seria de difícil execução em seres humanos, esbarrando em problemas éticos.…”