RESUMO
The study of cranial design and development in Gymnophthalmidae is important to understand the ontogenetic processes behind the morphological diversity of the group and to examine the possible effects of microhabitat use and other ecological parameters, as well as phylogenetic constraints, on skull anatomy. Complete morphological descriptions of embryonic skull development within Gymnophthalmidae are non-existent. Likewise, very little is known about the complete chondrocranium of the family. Herein, the development of the skull of the semi-fossorial lizard Ptychoglossus bicolor is described along with an examination of the chondrocranium of other gymnophthalmid taxa and the teiid Cnemidophorus lemniscatus. Cranial chondrification begins with early condensations in the ethmoid, orbitotemporal and occipital regions of the chondrocranium as well as the viscerocranium. Ossification of the skull starts with elements of the dermatocranium (pterygoid, prefrontal, maxilla and jugal). The orbitosphenoid is the last chondral bone to appear. At birth, the skull is almost completely ossified and exhibits a large frontoparietal fontanelle. In general terms, the chondrocranium of the gymnophthalmids studied is characteristic of lacertiform terrestrial lizards, in spite of their life habits, and resembles the chondrocranium of C. lemniscatus in many aspects. However, the gymnophthalmids show great variation in the orbitosphenoid and a complex nasal capsule. The latter exhibits greater development of some nasal cartilages, which make it more complex than in C. lemniscatus. These characteristics might be related to microhabitat use and the well-developed olfactory and vomeronasal systems observed within this clade.
Assuntos
Lagartos/embriologia , Crânio/embriologia , Animais , Osso Etmoide/embriologia , Osso Occipital/embriologia , Osteogênese/fisiologia , Osso Temporal/embriologiaRESUMO
AIMS: To evaluate the distribution of mucopolysaccharides and glycoproteins in the articular discs of temporomandibular joints (TMJs) in human fetuses at different stages of development in order to test the hypothesis that the development and histological maturation of the articular disc has already begun by the 12th week of gestation. METHODS: Eighteen human fetuses at gestational ages 12, 14, and 16 weeks were used (6 fetuses of each age). Sections (6 microm wide) of the articular discs were stained with trichromic stain for collagen fibers, Mayer's mucicarmine for mucopolysaccharides, and Schiff's periodic acid reaction for glycoproteins. The densities of the stained zones were measured by means of Image J software. The nonparametric Kruskal-Wallis test was used to evaluate the differences among stained zones in the 3 fetus groups. RESULTS: TMJ tissues of four of the six 12-week-old fetuses were stained positive for collagen fibers, mucopolysaccharides, and glycoproteins. In these fetuses the stain was localized to the articular posterior area and was denser in that area than in the middle and anterior areas. The stained areas in the 14-week-old fetuses were distributed throughout the articular discs, with isolated clear unstained areas. The stained areas of all the articular discs of the 16-week-old fetuses were more compact than those of the 12-and 14-week-old fetuses. In all the fetuses examined, the collagen fibers along the articular disc had a wavy appearance. The fossa of the temporal bone was observed in all the fetuses as a straight structure that was similar in the 3 fetus groups. The densities (mean +/- SD) of the stained zones were 38.36% +/- 3.39%, 59.5% +/- 1.56%, and 94.04% +/- 2.04% for 12, 14, and 16 weeks of gestation, respectively; these densities were significantly different (chi2 = 15.16; df = 2, P < .001). CONCLUSION: This study indicates that mucopolysaccharides and glycoproteins as well as collagen fibers are present at 12, 14, and 16 weeks of gestation. This suggests that the histological maturation of the articular disc has already begun at the 12th week and is complete by the 16th week of gestation.
Assuntos
Glicoproteínas/análise , Glicosaminoglicanos/análise , Disco da Articulação Temporomandibular/química , Disco da Articulação Temporomandibular/embriologia , Desenvolvimento Fetal , Colágenos Fibrilares/química , Idade Gestacional , Humanos , Estatísticas não Paramétricas , Osso Temporal/embriologia , Distribuição TecidualRESUMO
A silicone impression method to study the anatomy of the round window region was used in 102 temporal bones belonging to individuals aged from 4 months of fetal life to 3-year-old children as well as adults. A total of 2,142 measurements of the round window, oval window and round window fossula was made in the molds. The data demonstrate that the round window shows a diameter from 1.21 mm (average for the short axis) to 1.74 mm (average for the long axis) and the circular shape was present in 55% of the adult temporal bones and in 18.18% of the fetal and infantile ones. The adult dimensions of the measured structures are reached during fetal development.
Assuntos
Feto/embriologia , Janela da Cóclea/embriologia , Janela da Cóclea/crescimento & desenvolvimento , Elastômeros de Silicone , Osso Temporal/embriologia , Adulto , Envelhecimento/fisiologia , Cefalometria , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , MorfogêneseRESUMO
The fate of mesenchyme, which lines the fetal and newborn bony middle ear, is not well understood. The authors wished to test previous observations that a greater amount of mesenchyme was found in Potter's sequence (renal anomalies, pulmonary hypoplasia, and oligohydramnios). Using celloidin-embedded neonatal temporal bones (68 cases, 123 ears), with clinical and autopsy information, middle ear volumes were compared among diagnostic groups using analysis of variance. In 16 ears of Potter's sequence cases the volume of mesenchyme increased in proportion to the size of the middle ear. Conversely, in all other cases the volume of mesenchyme remained constant compared to increasing middle ear size. Both the volume of the bony middle ear and the volume of the air cavity increased at 15 mm3/500 g of body weight (gbw). Mesenchyme percentage decreased by 2%/500 gbw. Middle ear mesenchyme appears to recede rather than reabsorb. However, in Potter's sequence cases the volume of mesenchyme increases, raising issues of a missing renal signal that inhibits mesenchymal growth under normal circumstances.
Assuntos
Anormalidades Múltiplas/embriologia , Orelha Média/embriologia , Endoderma/patologia , Osso Temporal/embriologia , Anormalidades Múltiplas/patologia , Orelha Média/patologia , Humanos , Rim/anormalidades , Pulmão/anormalidades , Oligo-Hidrâmnio/patologia , Osso Temporal/patologiaRESUMO
The study, learning and teaching of the temporal bone complexity requires different methods. One of them, it's the corrosion cast technique (repletion-corrosion). Using soft masses in its final solid state permits to obtain casts of a big discriminating power. This methodology permits to study size, extension and relations of the temporal bone contents, working on with the classic methods of studying this bone.
Assuntos
Molde por Corrosão , Osso Temporal/anatomia & histologia , Resinas Acrílicas , Adulto , Feto/anatomia & histologia , Humanos , Osso Temporal/embriologiaRESUMO
Using a computer-aided three-dimensional reconstruction and measurement method, the authors studied the shape and dimensions of Scarpa's ganglion and interrelations of the ganglion to nearby important anatomical structures in 10 normal human temporal bones obtained from 10 individuals of different ages (12 gestational weeks to 72 years). In the postnatal cases, Scarpa's ganglion was shaped like a distorted hourglass. Although the shape of the ganglion varied somewhat among specimens, a superior division, inferior division, and isthmus ganglionaris were distinguishable in each case. Volume of the ganglion was relatively consistent after birth, so that width and height of the ganglion were inversely correlated with each other (linear regression analysis, P less than .05). There seemed to be, however, a possible postnatal increase in the distances from the ganglion to neighboring structures and in the length of the internal auditory canal; these increases were probably the result of postnatal growth of the temporal bone. Moreover, the width of the ganglion in any single specimen was found to correlate significantly positively with the distances from the ganglion to the vestibular end-organs and the length of the internal auditory canal in that specimen (linear regression analysis, P less than .01). This finding suggests that Scarpa's ganglion may be elongated secondary to the elongation of the vestibular nerve due to the growth of the temporal bone. In fetuses, each portion of the ganglion was less clearly identifiable than that portion in postnatal cases. The dimensions of Scarpa's ganglion were found to have reached maturity around the time of birth.
Assuntos
Nervo Vestibular/anatomia & histologia , Adolescente , Adulto , Idoso , Pré-Escolar , Feminino , Feto , Gânglio Geniculado/anatomia & histologia , Humanos , Processamento de Imagem Assistida por Computador , Lactente , Recém-Nascido , Terminações Nervosas/ultraestrutura , Sáculo e Utrículo/inervação , Canais Semicirculares/inervação , Lâmina Espiral/inervação , Osso Temporal/anatomia & histologia , Osso Temporal/embriologia , Osso Temporal/inervação , Nervo Vestibular/embriologiaRESUMO
Thirty right temporal bones of Brazilian fetuses (ranging from 14th to 36th weeks) were studied by the allometric method in order to define the pattern of the whole temporal bone weight growth and the weight growth of the temporal bone portions: squamous, petrous and tympanic. These data were compared to fetal weight. The increase of the data of the temporal bone shows a positive allometry except for the tympanic portion (isometry). The squamous portion shows the highest allometric coefficient. These data are important to the knowledge of the human skull growth.
Assuntos
Desenvolvimento Embrionário e Fetal , Osso Temporal/embriologia , Feminino , Humanos , Masculino , Tamanho do Órgão , Análise de RegressãoRESUMO
Foi feito um estudo, quantitativo do crescimento dos ossos temporal (pporçäo petrosa) e esfenóide (asas e corpo), em trinta fetos humanos brasileiros de ambos os sexos, aplicando o método alométrico (Huxley, 1932): Log Y = Log X + Log b, onde X representa a idade gestacional (em semanas pós-concepçäo, s.p.c.), o comprimento vértex-cóccix (em milímetros) e o peso do feto (em gramas), e Y, as medidas lineares dos ossos. Os resultados sugerem que o crescimento do esfenóide e da porçäo petrosa do temporal é alométrico positivo em relaçäo a idade gestacional e ao comprimento cértice-cóccix, e alométrico negativo em relaçäo ao peso do feto