Cranial growth centers: facts of fallacies?
Explore the source record for details and available documents.
SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The rapid proliferative expansion and complex morphogenetic events that coordinate the development of the face underpin the sensitivity of this structure to genetic and environmental insult and provide an explanation for the high incidence of midfacial malformation. Most notable of these malformations is cleft lip with or without cleft palate (CLP) that, with an incidence of between one in 600 and one in 1000 live births, is the fourth most common congenital disorder in humans. Despite the obvious global impact of the disorder and some recent progress in identifying causative genes for some prominent syndromal forms, our knowledge of the key genetic factors contributing to the more common isolated cases of CLP is still remarkably patchy. The current understanding of the molecular and cellular processes that orchestrate morphogenesis of the midface, with emphasis on events leading to fusion of the lip and primary palate, is detailed in this review. The roles of crucial factors identified from relevant animal model systems, including BMP4 and SHH, and the likely events perturbed by key genes pinpointed in human studies [such as PVRL1, IRF6p63, MID1, MSX1, and PTCH1] are discussed in this light. New candidates for human CLP genes are also proposed.
The relation between bone surface patterns and the rate of bone formation and destruction was studied by observing surface sections and ground sections. The material used consisted of the dried skulls of three pigs. Observations on surface sections revealed two prinicipal types of bone surface patterns, i.e. a type characterized by smoothness and regularity and a type characterized by roughness and irregularity. Observations on corresponding ground sections revealed that these patterns represent appositional surfaces and resorptive surfaces, respectively. Within each type of surface pattern, variations occurred. As judged from the corresponding ground section, these variations might express variations in growth rates.
Explore the source record for details and available documents.
Craniofacial growth has been the subject of numerous studies in which different techniques have been elaborated aiming to model this dynamic phenomenon in a rational manner. One of the methods employed is cephalometric analysis applied to the fetus. Generally, however, these studies are confined to the exploration of a single spatial plane (sagittal plane), whose orientation is never defined in a rigorous and perfectly reproducible manner. Thus, none of these analyses offers a formal growth model. This has led us to propose a new method of fetal cephalometric study taking into account criteria for proper reproducible analysis: spatial exploration of the head performed through three-dimensional tomodensitometric images and precise location of landmarks and reproducibility of the orientation of each image, which is assured by reference to the vestibular orientation (based on the external semicircular canals), as has been described by Girard and Perez and further developed by Fenart. When the labyrinth is developed, this orientation does not change during the growth stages of the head, even with craniofacial deformities. This permits application of this orientation on fetuses and the superposition of images of different subjects. The methodology is presented using two normal human fetuses, and the advantages of this computerized tool are discussed.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
This study was undertaken to ascertain the changes of fetuses in craniofacial dimension and to evaluate the growth and development during fetal period. Lateral cephalograms by soft X-ray were taken from 64 fetuses and were measured in linear and angular aspects. The following conclusions were obtained. 1. The linear increase rates of anterior cranial base length exceeded those of the posterior cranial base length. 2. Growth increments on horizontal dimension were greater than vertical dimension in the maxilla. 3. The cranial base angle was almost constant after fetal period 13 weeks with the average angle of 130 degrees. 4. The angle between anterior cranial base and palatal plane was decreased gently during fetal period.
The aim of this study was to investigate dynamics of the cranial base angle changing during the second trimester of the normal intrauterine growth and development. The material consisted of 35 fetuses, both sexes, derived from artificial abortions of the uncomplicated pregnancies, gestational ages from the 14th to the 23rd week. Measurements of the cranial base angle were assessed from tracings of lateral cephalometric radiographs. It was found that cranial base angle decreased with the age for about 2.25 degrees per week; from 160 degrees in the 14th week to 140 degrees in the 23rd week. However, significant individual variations of the cranial base angle changes also existed. Thus, among the 99% of fetuses investigated, angle of the cranial base decreased from about 2.00 degrees to 2.50 degrees per week.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.