Desarrollo de los Miembros en los Vertebrados / Limb Development in Vertebrates

Los miembros de los vertebrados son estructuras complejas con tres ejes a considerar, proximal-distal, anterior-posterior y dorsal-ventral. La batería de genes involucrados en la formación de estas estructuras está bastante conservada en la evolución. El esbozo del miembro está compuesto de células mesenquimáticas indiferenciadas que derivan del mesodermo lateral somático cubiertas por ectodermo. La cresta apical ectodérmica es un centro productor de señales para el desarrollo y se ubica en el margen distal del esbozo de miembro. La zona de progreso esta a continuación y permite el crecimiento del miembro. El tipo de estructuras formadas a lo largo del eje proximal distal es especificado por los genes Hox. La proteína Sonic Hedgehog está involucrada en la regulación de la actividad de un segundo centro de señales conocido como zona de actividad polarizante. Los miembros también tienen una polaridad dorso ventral. La proteína WNT7A secretada desde el ectodermo dorsal, instruye a las células mesenquimales circundantes a diferenciarse en estructuras dorsales mientras que Engrailed 1 expresado en el ectodermo ventral, inhibe la expresión de WNT7A en esta zona del esbozo de miembro promoviendo la formación de estructuras ventrales.

Members of vertebrates are complex structures with three lines to consider, proximal-distal, anterior-posterior and dorsal-ventral. The battery of genes involved in the formation of these structures is well conserved in evolution. The outline of the member is composed of undifferentiated mesenchymal cells derived from somatic lateral mesoderm covered by ectoderm. The apical ectodermal ridge is a signal producing center for development and is located in the distal margin of the outline of a member. The area of progress is below and allows the growth of the member. The type of structures formed along the proximal distal axis is specified by Hox genes. Sonic Hedgehog protein is involved in regulating the activity of a second signaling center known as the zone of polarizing activity. Members also have a dorsal ventral polarity. The Wnt protein secreted from the dorsal ectoderm, instructs the surrounding mesenchymal cells to differentiate into dorsal structures whereas Engrailed 1 expressed in the ventral ectoderm, inhibit the expression of WNT7A outline in this membership area promoting the formation of ventral structures.

Reprodutibilidade do volume de membros fetais pela ultrassonografia tridimensional utilizando o método XI VOCAL / Reproducibility of fetal limbs volume by three-dimensional ultrasonography utilizing the XI VOCAL method

OBJETIVO: Avaliar a reprodutibilidade do volume do braço e coxa fetais aferido pela ultrassonografia tridimensional utilizando o método eXtended Imaging Virtual Organ Computer-aided AnaLysis (XI VOCAL). MATERIAIS E MÉTODOS: Realizou-se estudo de reprodutibilidade com 43 fetos normais entre 20 e 37 semanas. Para o cálculo do volume do braço e coxa fetais utilizou-se o método XI VOCAL com delimitação de 10 planos consecutivos. Para o cálculo da variabilidade interobservador, um examinador realizou uma medida do volume do braço e coxa dos 43 fetos, enquanto um segundo examinador, sem o conhecimento prévio dos resultados do primeiro examinador, realizou uma segunda medida dos mesmos volumes. Utilizaram-se, para os cálculos estatísticos, o coeficiente de correlação intraclasse (ricc), gráficos de Bland-Altman e teste t-Student pareado (p). RESULTADOS: Observou-se alta reprodutibilidade interobservador. Para o volume do braço, obtiveram-se ricc = 0,996 (intervalo de confiança [IC] 95 por cento: 0,992; 0,998) e média das diferenças = 0,13 ± 1,29 por cento (95 por cento limites de concordância: -2,54; +2,54 por cento). Para o volume da coxa, obtiveram-se ricc = 0,997 (IC 95 por cento: 0,995; 0,999) e média das diferenças = 0,24 ± 7,60 por cento (95 por cento limites de concordância: -7,6; +7,6 por cento). CONCLUSÃO: O volume do braço e coxa fetais aferido pela ultrassonografia tridimensional utilizando o método XI VOCAL apresentou elevada reprodutibilidade interobservador.

OBJECTIVE: To assess the reproducibility of fetal thigh and upper arm volumes measurement by threedimensional ultrasonography utilizing the eXtended Imaging Virtual Organ Computer-aided AnaLysis (XI VOCAL) method. MATERIALS AND METHODS: This reproducibility study enrolled 43 pregnant women with healthy singleton pregnancies between 20 and 37 gestational weeks. The XI VOCAL 10 planes was the method utilized for volumetric measurement of the fetal limbs. The calculation of the interobserver reproducibility was based on blind volumetric measurements of fetal thighs and upper-arms performed by two observers in 43 fetuses. Intraclass correlation coefficient (ICC), Bland-Altman plots and paired Student's t-test (p) were utilized in the statistical analysis. RESULTS: A high interobserver reproducibility was observed. For the upper arm volume ICC was 0.996 (confidence interval [CI] 95 percent: 0.992; 0.998) and mean difference = 0.13 ± 1.29 percent (95 percent limits of agreement: -2.54; +2.54 percent). For the thigh volume, ICC was 0.997 (CI 95 percent: 0.995; 0.999) and mean difference = 0.24 ± 7.60 percent (95 percent limits of agreement: -7.6; +7.6 percent). CONCLUSION: Fetal thigh and upper arm volumes measured by three-dimensional ultrasonography with the XI VOCAL method presented a high interobserver reproducibility.

Hemihyperplasia syndromes.

OBJECTIVE: Hemihyperplasia is a heterogenous group of disorders characterized by asymmetric limb growth. There is considerable confusion regarding their classification and ascertainment into various syndromes. We tried to look into the various aspects of hemihyperplasia syndromes. METHODS: Records of 17 consecutive cases of hemihyperplasia were reviewed and were ascertained into various syndromes based on available literature and diagnostic criteria. RESULTS: Of the 17 cases with hemihyperplasia, 3 cases satisfied the diagnostic criteria for Proteus syndrome. One patient each was ascertained as Klippel Trenaunay Weber syndrome and Hemihyperplasia- Multiple lipomatosis. 9 cases were classified as isolated hemihyperplasia. We found two novel associations with hemihyperplasia; namely Ehlers-Danlos syndrome like skin changes and Poland anomaly on the affected side. The remaining 3 cases had miscellaneous disorders with limb asymmetry, namely Neurofibromatosis Type I in 2 cases and Olliers disease in one case. CONCLUSION: Efforts to diagnose syndromes of hemihyperplasia help in genetic counseling.

Histology of vitamin A induced ectopic limbs and normal hind limbs in tadpoles of Polypedates maculatus.

Marked histological similarities were observed between normal and vitamin A induced ectopic limb buds of P. maculatus. However, close association of nephric tubule and lateral plate mesoderm, as seen in normal hind limb bud does not seem to be essential for ectopic limb development. The ectopic limbs tend to develop in pairs.

Stature and limb lengths as indicators for age estimation

In this study five hundered cases with age range from birth to 20 years were taken from Minia district of Upper Egypt. The subjects were divided sexwisely, into 5 age groups : newborn, 5, 10, 15 and 20 years and measured for height, upper limb length and lower limb length. Stature of the newborn was calculated by adding the crown rumb length to the lower limb length. Standards for stature and limb lengths at the different ages are presented in the form of tables and figures. The point at which the lengths of the limbs were equal was at 3 years and 10 months for boys and 3 years and 6 months for girls. After this age, the lower limb becomes longer than the upper limb. The point of intersection is an excellent developmental age markers which may be considered as a very simple identification tool in that age. Furthermore, ratios between segment lengths can be used as a quick and simple tool of age identification in accidents and crimes where parts of cadaver are the only presenting signs

Perfil antropométrico de miembros superiores e inferiores en adolescentes de Antofagasta / Anthropometric profile of the upper and lower extremities in adolescents of Antofagasta

Análisis de crecimiento y desarrollo segmentario de miembros superiores e inferiores realizado en 873 escolares de ambos sexos de la ciudad de Antofagasta, de 10 a 14 años en damas y de 13 a 15 años en varones. Este estudio permite aportar mayores datos para contribuir al intento de definir el perfil antropométrico segmentario de los miembros superiores e inferiores en el hombre chileno en las edades consideradas en el presente trabajo. Las mediciones se cumplieron en escolares de morfología corporal normal y que no habían sufrido enfermedades de larga duración. Se logran conclusiones puntuales en cada una de las comparaciones de crecimiento en los diversos segmentos de las extremidades en relación a sexo y edad de la muestra