Alphonse R. Burdi

The chronology of adipose tissue appearance and distribution in the human fetus

Timing of first appearance and subsequent distribution of adipose tissue were assessed in 488 normal-for-age human fetuses. The sample represented each of the three trimesters of normal pregnancies. Light microscopy showed that adipose tissue first appears and progressively develops from the 14th to 24th week of gestation (100-216 mm crown-rump length) in those areas where it characteristically accumulates after birth. No significant sex differences were found in patterns of early fat deposition. It is suggested that the second trimester of gestation is the critical or key period in fat adipogenesis.

Infants and children in the adult world of automobile safety design: Pediatric and anatomical considerations for design of child restraints☆

U.S.A. Abstract-The infant and child differ structurally from the adult in a number of ways which are critical to the design for protection against impact forces and for adequate occupant restraint systems. The purpose of this paper is to bring together a profile of the anatomy, anthropomctry, growth, and development of the infant and child. Age differences related to the proper design of child restraint systems are emphasized. Problems discussed include child-adult structural differences, center of gravity of the body, the head mass in relation to the neck and general body proportions, positions of key organs, and biomechanical properties of tissues.

Growth and development of human adipose tissue during early gestation

805 normal-for-age human embryos and fetuses were used to study early prenatal fat development. The investigation included observations on stages of fat morphogenesis at the light microscopic level and computerized image analyses of fat lobule size and number. The buccal fat pad was selected as a model system for the analyses. Fat tissue differentiates between the 14th and the 16th weeks: there are five morphogenic phases in adipose tissue formation, strongly associated with the formation of blood vessels. Fat lobules are the earliest structures to be identified before typical vacuolated fat cells appear. Concerning fat lobule size and number, we show that after the 23rd week the total number of fat lobules remains approximately constant, while from the 23rd to 29th week the growth of adipose tissue is determined mainly by an increase in size of the lobules. These results suggest that the 14th through the 23rd week is a sensitive period in fat lobule development, and that disturbances of normal adipogenesis during this period may play a role in the etiology of obesity in later life.

Toluidine Blue-Alizarin Red S Staining of Cartilage and Bone in Whole-Mount Skeletons in Vitro

Cartilage and bone of the developing skeleton can be reliably differentiated in whole-mount preparations with toluidine blue-alizarin red S staining after FAA fixation. The recommended staining procedure is based chiefly on the use of newborn white and Swiss-Webster mice, 4-9 days postnatal, but was tested also on mice and rats 3-8 wk of age. Procedure: Sacrifice, skin, eviscerate, remove body fat, and place specimens in FAA (formalin, 1; acetic acid, 1; 70% alcohol, 8) for approximately 40 min. Stain in 0.06% toluidine blue made in 70% ethyl alcohol for 48 hr at room temperature. Use 20 volumes of stain solution to the estimated volume of the specimen. Destain soft tissues in 35% ethyl alcohol, 20 hr; 50%, 28 hr; and 70%, 8 hr. Counterstain in a freshly prepared 1% aqueous solution of KOH to which is added 2-3 drops of 0.1% alizarin red S per 100 ml of solution. Each day for 3 days, transfer the specimen to a fresh 1% KOH-alizarin mixture, or until the bones have reached the desired intensity of red and ...

Prenatal Growth of the Human Vomeronasal Organ

Vomeronasal organs (VNOs) are paired epithelial structures located adjacent to the nasal septum that form in the late first trimester of human fetal development. Although VNOs have long been known to exist in fetal and adult humans, some studies continue to suggest that these structures may be degenerative or functionless. Little is known of the growth of the VNO.

Searching for the vomeronasal organ of adult humans: preliminary findings on location, structure, and size.

The adult human vomeronasal organ (VNO) has been the focus of numerous recent investigations, yet its developmental continuity from the human fetal VNO is poorly understood. The present study compared new data on the adult human “VNO” with previous findings on the fetal human VNO. Nasal septa were removed from twelve adult human cadavers and each specimen was histologically sectioned. Coronal sections were stained with hematoxylin‐eosin and periodic acid‐Schiff‐hematoxylin. The sections were examined by light microscopy for the presence of VNOs and the anterior paraseptal cartilages (PC). VNOs were quantified using a computer reconstruction technique to obtain VNO length, volume, and vomeronasal epithelium (VNE) volume. Histologically, VNOs and PCs were identified in eleven specimens. VNOs had ciliated, pseudostratified columnar epithelium with goblet cells. Variations (e.g., multiple communications to the nasal cavity) were observed in several specimens. Quantification was possible for 16 right or left VNOs. Right or left VNOs ranged from 3.5 to 11.8 mm in length, from 1.8 to 33.8 x 10‐4cc in volume, and from 2.7 to 18.1 x 10‐4cc in VNE volume. Results indicated that the adult human VNO was similar in VNE morphology, lumen shape, and spatial relationships when compared to human fetal VNOs. By comparison with previous fetal VNO measures, mean VNO length, volume, and VNE volume were larger in adult humans. These results support previous suggestions that postnatal VNO growth occurs. Findings on location and spatial relationships of the adult VNO were similar to those seen in human fetuses, but critical questions remain regarding the ontogeny of the vomeronasal nerves and VNE. Microsc. Res. Tech. 41:483–491, 1998.

Mandibular Fractures as Related to the Site of Trauma and the State of Dentition

With sufficient energy imparted to the mandible by an impact, the bone will fracture. But where? Is the location of mandibular fractures haphazard and arbitrary, or are there predisposing factors which tend to influence this location? No doubt the shape of the bone itself plays an important role in determining the location of some of the fractures. The narrow neck of the mandible, with its reduced cross-sectional area, is probably less strong than the body or the symphysis. Also in this regard the magnitude of the energy of the impact will be significant. If the amount of energy imparted to the mandible is above the elastic limit of the bone, a fracture will occur, with most of the energy being dissipated in producing the one fracture. However, if the magnitude of the energy greatly exceeds the elastic limit, more fractures are likely to be produced. Does the state of dentition or the site of trauma have any influence on the location of these fractures? Up to this time, no clinical or experimental evidence has been presented to substantiate or refute these questions. It is the purpose of this report to present data regarding the relationship of the location of mandibular fractures and number of fractures with the site of impact, the state of dentition, and the age of the individual.

Morphogenesis of Mandibular Dental Arch Shape in Human Embryos

Changes in shape of the mandibular dental arch were demonstrated in a developmentally representative sample of human embryos. Each reconstructed arch was described in terms of a conformance to a reference geometric curve; ie, catenary. Cross-sectional sample trends showed that the initial dental lamina is anteroposteriorly flattened during the sixth week and begins a progressive elongation and conformance to the catenary curve in 8½-week embryos.

Developmental Advancement of the Male Dentition in the First Trimester

During postnatal development the female is more advanced than the male in calcification and eruption of all permanent teeth, except for the third molar. In deciduous teeth the direction is reversed; males are slightly more advanced (H. V. MEREDITH, J Dent Res 25:4366, 1946). The direction and the magnitude of prenatal dental dimorphism is of interest, but has not been systematically explored. When reviewing first-trimester human embryos, abnormal specimens were excluded after gross and microscopic examinations. Histologic sections of 52 males and females were then available in the 14 to 58 mm crown-rump (C-R) range. The embryos were matched for sex and for size within + 1.0 mm and comparisons of dental development were made on a matched basis. Except for the embryos where suitable sex and size matches could not be made, males were advanced in all deciduous

Effect of Experimental Surgery on Mandibular Growth in Syrian Hamsters

Enucleation of the incisor germinal center and extraction of molars in the mandibles of young hamsters produced a significant decrease in the size of the mandibular body, loss of normal occlusion, and a shift of the mandibular body medially and cranially. Condylectomies mainly affected the length of the mandible and were closely related to loss of the articular cartilage and impairment of ramal growth.