Biomedical subjects

Renata Peterková

Publications and source records attributed to Renata Peterková.

4 recordsLinked to original sources

PubMed2004

Origin and developmental fate of vestigial tooth primordia in the upper diastema of the field vole (Microtus agrestis, Rodentia).

OBJECTIVE: Odontogenesis in voles is a convenient model to test hypotheses on tooth development generated from investigations in the mouse. Similar to other rodents, the functional dentition of the vole includes a toothless diastema. At its mesial end, a vestigial tooth bud has been found in the upper jaw of vole embryos. The aim of this study was to analyse the developmental dynamics of vestigial tooth structures in the upper diastema of the field vole and to compare it with the situation in the mouse. DESIGN: The development of odontogenic structures in the upper diastema of the field vole was investigated using serial histological sections and three-dimensional (3D) computer-aided reconstruction. RESULTS: A transient continuous dental lamina in the upper diastema of the field vole extended mesially to the first molar primordium, but was not continuous with the dental lamina in the incisor region. At its mesial limit, a large vestigial tooth primordium was regularly present. A further distinct vestigial bud was located mesially to the first molar primordium. The segmentation of the dental lamina suggested a potential to give rise to further vestiges in the upper diastema of the vole. CONCLUSIONS: In the prospective diastema of the vole exists as in the mouse a continuous dental lamina. Beside the prominent vestigial tooth bud in the mesial diastema, a further large bud was transiently located in front of the molars. The incorporation of dental epithelium into the first upper molar (M(1)) primordium in the vole differs from that in the mouse.

Animals↗

PubMed2003

The developing mouse dentition: a new tool for apoptosis study.

Developing limb or differentiating neural and blood cells are traditional models used to study programmed cell death in mammals. The developing mouse dentition can also be an attractive model for studying apoptosis regulation. Apoptosis is most extant during early odontogenesis in mice. The embryonic tooth pattern is comprised not only of anlagen of functional teeth (incisor, molars), but also of vestiges of ancestral tooth primordia that must be suppressed. Apoptosis is involved in (a) the elimination of vestigial tooth primordia in the prospective toothless gap (diastema) between the incisor and molars and (b) the shaping of germs in functional teeth. This type of apoptosis occurs in the dental epithelium according to a characteristic temporo-spatial pattern. Where apoptosis concentrates, specific signaling is also found. We proposed a hypothesis to explain the stimulation of apoptosis in the dental epithelium by integrating two concepts: (1) The regulation of epithelial budding by positional information generated from interactions between growth-activating and growth-inhibiting signals, and (2) apoptosis stimulation by the failure of death-suppressing signals. During the budding of the dental epithelium, local excess in growth inhibitors (e.g., Bmps) might lead to the epithelial cells' failure to receive adequate growth-activating (apoptosis-suppressing) signals (e.g., Fgfs). The resulting signal imbalance leads to cell "suicide" by apoptosis. Understanding of apoptosis regulation in the vestigial tooth primordia can help to elucidate the mechanism of their suppression during evolution and to identify factors essential for tooth survival. The latter knowledge will be important for developing a technology of tooth engineering.

Animals↗

PubMed2002

Evolutionary implications of the occurrence of two vestigial tooth germs during early odontogenesis in the mouse lower jaw.

The study of closely-spaced developmental stages reveals the occurrence of three distinct dental segments during early odontogenesis in the ICR mouse lower jaw: the mesial (MS), the second rudimentary (R2), and the molar segments. At embryonic day (ED) 12.5, the MS displays an accessory bud, which regresses rapidly and disappears at ED 13.5. The R2 segment reaches a wide bud stage at ED 13.5 and then merges with the mesial end of the emerging first lower molar (M1) cap before ED 15.0. The MS and R2 segments never develop into functional teeth and are classified as vestigial tooth germs. Depending on their developmental chronology and on the position they occupy along the prospective mandibular tooth row, MS and R2 segments are putatively assigned to primordia of a third (dP3) and fourth (dP4) lower deciduous premolar, respectively. Evolutionary implications of these developmental data are discussed.

Animals↗

PubMedDate not supplied

Chernobyl: prenatal loss of four hundred male fetuses in the Czech Republic.

The long-standing higher male birth fraction is considered an indicator of reproduction stability and health. In contrast, a decrease in the male birth fraction has been reported after prenatal exposure to environmental chemical factors. There is generally higher vulnerability of boys to prenatal damage by environmental stress. We formulated a hypothesis that the Chernobyl disaster might also have had a greater negative impact on male than on female fetuses, leading to their selective loss and to a decrease in the male birth fraction. To test this hypothesis, we examined demographic data on monthly natality in the territory of the Czech Republic from 1950 to 1999. The male birth fraction was higher in the Czech Republic each month between 1950 and 1999 except November 1986, when it was significantly (P< 0.05) reduced. This finding suggests a selective negative effect of the Chernobyl accident on male fetuses during the 3rd month of prenatal development.

Abortion, Spontaneous↗