Effects of Restrained Fetal Movement on the Development of the Rat Hip Joint

Abstract

The effect of fetal movement on the development of the hip joint was examined by restraining the leg movement using exo utero operation in rat fetuses. At embryonic day (E) 16.5, when the hip joint cavity starts to form, one side of the hind limb was sutured onto the embryonic membrane. After exo utero development to E18.5, the hip joint of the operated side was compared morphologically with those of the unoperated side, sham‐operated and unoperated in utero controls. The largest diameter of the femoral head (FH) and the gross morphology of the joint cavity of the operated side was not different from those of controls. By light microscopy (LM), the surface of the control E18.5 FH and acetabulum was smooth and covered by thin scale‐shaped cells which were partially pyknotic, and oval‐shaped cells underneath were rather regularly arranged in a thickness of a few cells. By transmission electron microscopy (TEM), scale‐shaped cells covered the FH surface incompletely, and the spaces in‐between were filled with the intercellular matrix. Oval‐shaped cells underneath had well developed rough endoplasmic reticulums. By scanning electron microscopy (SEM), mounds and grooves on the FH surface were evident at E17.0 but became unclear at E18.5. Subsurface collagen fibers formed a coarse meshwork at E17.0 but formed bundles at E18.5. On the operated side, by LM, the surface of the FH and acetabulum was irregular and lined by spindle‐shaped cells, whereas the underlying mesenchymal cells also showed an irregular cell shape and arrangement. By TEM, collagen fibrils in intercellular spaces were dense but did not generally form bundles. By SEM, the FH surface was rugged with banks and subsurface collagen fibers did not form bundles but remained as a dense meshwork. These results suggest that the fetal hind limb movement influences development of the surface structure of the FH and acetabulum and that this system may be useful to study prenatal etiology of the congenital dislocation of the hip.

Application of the mouse exo utero development system in the study of developmental biology and teratology

“…The significance of fetal joint movement in normal joint development remains unknown. Kihara et al . (1998) examined the effect of restraining fetal hip movement on joint development by binding the hindlimb to the embryonic membrane with a 9–0 thread in E16.5 rat fetuses.…”

Perinatal development of the rat hip joint with restrained fetal movement

“…The animals used were the same as above. We performed the ex0 utero operation at E16.5 as in the previous study (Kihara et al, 1998). At E16.5, pregnant rats were anesthetized with 50 m a g body weight pentobarbital for the fetal operation.…”

“…Immobilization of the hip joint in postnatal rats for the dislocation of the hip joint induced progressive acetabular dysplasia and anatomical abnormalities of the head and neck of the femur during the postnatal period (Sijbrandji, 1965). We previously studied the effects of fetal movement of the hind limb on the formation of the hip joint in rats, and reported that the fetal hind limb movement influenced the development of the femoral head (FH) and acetabulum (Kihara et al, 1998). We tied the hind limb on one side onto the embryonic membrane to restrict the range of motion at the hip joint at embryonic day (E) 16.5 using a technique of ex0 utero development (Muneoka et al, 1986;Hatta et al, 1994aHatta et al, , 1994bNaruse el al., 1996;Sekimoto et al, 1997;Zhang et al, 1998, Hatta et al, 2002, Matsumoto et al, 2002.…”

“…We tied the hind limb on one side onto the embryonic membrane to restrict the range of motion at the hip joint at embryonic day (E) 16.5 using a technique of ex0 utero development (Muneoka et al, 1986;Hatta et al, 1994aHatta et al, , 1994bNaruse el al., 1996;Sekimoto et al, 1997;Zhang et al, 1998, Hatta et al, 2002, Matsumoto et al, 2002. The surface of the FH of the operated fetuses was irregular and rugged with banks, and subsurface collagen fibers did not form bundles but remained as a dense meshwork at E 18.5 in light and scanning electron microscopy (LA4 and SEM) (Kihara et al, 1998). We observed the hip joint of rat fetuses at E18.5 in the previous study; however, the findings were not sufficient to evaluate the effect of fetal movement on the development of the hip joint till term or to analyze the results correlatively with those from postnatal studies.…”

Mouse exo utero development system: Protocol and troubleshooting

“…This experimental system allows researchers to manipulate or operate on mid-to-late-gestation live embryos of mice or rats and keep them alive in situ until the analysis of their effects at a desired time point either pre-or postnatally. For example, we can examine the effects of injecting bioactive molecules or cells into targeted parts of a live embryo (Hatta et al 1994;Zhang et al 1998;Hatta et al 2002), transferring DNA into cells in a limited area (Takiguchi-Hayashi et al 2004), destroying specific embryonic regions (Naruse & Kameyama 1990;Naruse & Keino 1993;Naruse et al 1996), or performing fetal surgery (Kihara et al 1998;Habib et al 2005). In principle, the exo utero system enables us to make a time-and region-specific intervention into developmental phenomena simply by allowing us to choose the desired time and region for manipulation.…”