Palate In Fetal Mice Research Articles

Susceptibility of Day‐12.5 and Day‐13.5 Fetal Mouse Palates Cultured in Vitro to 5‐Fluorouracil and Hydroxyurea

Abstract The maxillary regions of day‐12.5 and day‐13.5 ICR mouse fetuses were cultivated in a chemically‐defined serumless medium by a suspension culture technique to examine the toxic effects of 5‐fluorouracil (5‐FU) and hydroxyurea (HU) on cultured palates and to compare the sensitivity of fetal mouse palates at different stages of development. The palates of day‐12.5 and day‐13.5 fetal mice were explanted and exposed in vitro for 72 hr to 0.1–50 μg 5‐FU/ml or to 5–76 μg HU/ml. 5‐FU inhibited the growth and fusion of day‐12.5 palatal shelves in vitro dependently on its concentrations. Day‐13.5 palates were significantly less sensitive to 5‐FU than day‐12.5 palates, and the minimal toxic concentrations (MTCs) of 5‐FU were 0.1 and 10 μg/ml for day‐12.5 and day‐13.5 fetal palates, respectively. HU inhibited the in vitro growth and fusion of day‐12.5 fetal palatal shelves in a concentration dependent manner, but only slightly suppressed the growth of day‐13.5 fetal palates. The MTCs of HU were 19 and 76 μg/ml for day‐12.5 and day‐13.5 fetal palates, respectively. Therefore, day‐12.5 fetal mouse palates (at stage‐1 or earlier stages of palatogenesis) seemed significantly more susceptible to these teratogenic chemicals than day‐13.5 fetal palates (at stages 2–3 of palatogenesis). The palates of day‐12.5 ICR fetal mice may be more suitable than day‐13.5 palates for in vitro teratogen screening and for the study of mechanisms of normal and abnormal palatogenesis.

Cytochemical identification of programmed cell death in the fusing fetal mouse palate by specific labelling of DNA fragmentation.

The process of palate fusion was examined in 13- and 14-day-old mouse fetuses by using in situ staining for nuclear DNA fragmentation (TUNEL method) and immunofluorescent staining for keratin, with special reference to the disruption of the midline epithelial seam. TUNEL-positive cells were found in the disappearing midline seam and the oral and nasal epithelial triangles at some late stages of palate fusion, but not in the palatal shelves prior to contact or in the intact midline epithelial seam. It seems that DNA fragmentation or apoptosis is required for the midline epithelial seam to disrupt, but may not be necessary for initial contact of palatal shelves or for the epithelial fusion of opposing palatal shelves. A similar sign of apoptotic cell death was observed in the disappearing epithelial seam between the fusing nasal septum and dorsal palate. We have demonstrated that apoptotic programmed cell death does occur at some stages of palate fusion, although the present results do not exclude the possibility of epithelial-mesenchymal transformation and the oral and nasal migration of midline epithelial cells.

Expression of the epidermal growth factor receptor in developing fetal mouse palates: An immunohistochemical study

Epidermal growth factor (EGF) stimulates the growth of various tissues and, therefore, EGF receptor expression in fetal tissues may play a key role in organogenesis. We have examined immunohistochemically the ontogeny and localization of the EGF receptor in the fetal mouse palate during in vivo and in vitro palatogenesis using the anti-human EGF receptor rabbit antibody. Immunoreactive products against the EGF receptor were observed in the palatal tissue examined on days 12, 13, and 14 of gestation. On days 12 and 13, the immunoreactive products were predominantly positive on the oral and medial edge epithelia but were minimal on the epithelium of the vertical shelf. The EGF receptor immunoreactivity was less intense in the posterior palate as compared with the midpalatal region. In the fusing palate of day 14 fetuses, the cells forming the midline epithelial seam were continuously positive for EGF-R immunoreactivity. The mesenchyme of palatal shelves also showed regional heterogeneity and temporal sequence in EGF receptor expression. The localization of the EGF receptor in fetal mouse palates cultured in a serumless medium generally simulated that observed in vivo.

Development of the Fetal Mouse Palate in Suspension Organ Culture

Explanted palates of day 12 and day 13 mouse fetuses were cultured in a chemically defined serumless medium for 48-72 h by a suspension culture technique. The palate of day 12 fetuses closed successfully within 72 h and that of day 13 fetuses within 48 h. Both macroscopically and histologically, the in vitro fusion of palatal shelves simulated the palatogenetic process in vivo. This novel technique for culturing the fetal mouse palate may be of potential use for the study of palatogenesis and in developmental toxicology.

Immunohistochemical study on epidermal growth factor receptor in developing fetal mouse palates

Immunohistochemical study on epidermal growth factor receptor in developing fetal mouse palates

Influence of H-2-linked genes on glucocorticoid receptors in the fetal mouse palate.

The binding of 3H-dexamethasone to cytosolic receptors in fetal jaws and in cytosols and nuclei of primary cell cultures of fetal palates was studied in various congenic strains of mice. The amount of specific binding was greater in palatal tissues from B10.A and B10.A(2R) mice than in B10 or B10.A(5R) preparations. These differences were not observed in the liver. Since the strains with higher levels of glucocorticoid receptor are known to be more susceptible to cortisone-induced cleft palate than the strains with low receptor levels, it is suggested that quantitative variation in receptor levels may be involved in determining H-2-linked differences in cleft-palate susceptibility. Whether or not this is the case, it appears that an H-2-linked gene affects the quantity of a cytosolic glucocorticoid-binding protein which translocates to the nucleus.