The inguinal canal is an anatomically complex region. Although much has been written about the gubernaculum and the descent of the testis, little is known about the development of the abdominal wall itself. We dissected this inguinal canal in 75 fetuses between 10 and 25 weeks of gestation, 42 males and 33 females. We identified the anterior body-wall muscular layers, located the gonads and uterus, and observed the formation of the scrotum. The gubernaculum was dissected, from the deep to the superficial ends and its distal attachments were determined. We proved that the muscular-fibrous layers of the wall were well-differentiated and observed how the inguinal canal enlarged with embryological development. In only one of the cases, an abnormal testis was found located in the scrotum. The upper end of the gubernaculum inserted into the inferior pole of the testis or the lateral angle of the uterus, according to gender. The lower end was attached by one or multiple tails, mainly on the pubic bone. This fact explained the clinical findings of ectopic testis. Observations of the abdominal wall and its relationship with the gubernaculum assisted us in explaining the development of the inguinal region, the formation of the inguinal canal, and the presence of the gubernaculum, in both genders. We intend to explain how the deep inguinal ring moves upwards, bringing the gubernaculum along with it, and thus determines the final form of the inguinal canal.
En la etapa fetal se observa un rápido incremento de la masa corporal y de todas las dimensiones. La literatura evidencia discrepancias sobre los criterios para determinar el estadio fetal post-mortem, en relación a los parámetros morfométricos utilizados, por lo que nuestro objetivo fue comparar la medición morfológica directa (vertex-coxis, tabla de Hansmann) con la ultrasonografía (medición del fémur), para establecer el grado de confiabilidad en la determinación post-mortem del estadío fetal. Se utilizaron 120 fetos: 1) grupo A (60 fetos) estadificado ecográficamente y 2) grupo B (60 fetos) estadificado por tabla de Hansmann. A ambos grupos se le realizaron múltiples mediciones siguiendo parámetros probados según la literatura internacional. Se utilizó calibre de precisión. Parámetros evaluados: longitud vertex-coxis, circunferencia cefálica, diámetro cefálico occipito-frontal, biparietal, longitud mentón-vertex, perímetro toráxico-transverso, circunferencia abdomi-nal y longitudes de brazo, antebrazo, mano, muslo, pierna y pie. Estos valores fueron agrupados por semanas, obteniéndose la media y aplicándose la prueba t de Student. Los resultados demostraron que la diferencia entre los parámetros medidos en el grupo A y en el grupo B eran significativas en todas las semanas, por lo que se observa disparidad en la determinación del estadio fetal por ecografía y los registros correspondientes a la medición vertex-coxis (tabla de Hansmann) postmortem. Concluímos que los resultados obtenidos por ambas modalidades de medición son diferentes para una misma edad gestacional y, por ende, resultaría más apropiado referirse a fetos con ciertas dimensiones según alguno de estos parámetros que a “edad gestacional”.In fetal stage, body mass and measurements quickly increase. Scientific literature shows differences on the criteria to determine the post-mortem fetal stage, depending on morphometric parameters. Our objective was to compare both methods, direct morphologic measures (crown-rump length, Hansmann table) and ultrasonography (femur measurement), to establish their reliability on post-mortem determination of fetal age. One hundred and twenty fetuses were studied: 1) group A (60 fetuses) sonographically staged and 2) group B (60 fetuses) staged according to Hansmann table. Many measurements were performed on both groups, following internationally determined parameters. We used a precision gauge. Considered parameters were: crown-rump length, head circumference, occipito-frontal diameter, bi-parietal length, chin-vertex length, thoracic transverse perimeter, abdominal circumference, arm, forearm, hand, thigh, leg and foot lengths. Obtained information was grouped by weeks. We calculated the data mean and significant difference was managed by Student t-test. Results demonstrated significant difference in the considered parameters between group A and B, and then, to determine the fetal age.We conclude that results obtained by both measuring modalities were different for the same gestational age, and therefore, it should be more appropriate to consider fetuses by measures obtained following certain parameters than by “gestational age”.
El timo se origina de la tercera bolsa faríngea, durante la 5ª semana de gestación, cuando migra junto con las paratiroides inferiores, hasta alcanzar su posición definitiva. El crecimiento y desarrollo del timo continúa después del nacimiento hasta la pubertad, ocupando una posición cervico-torácica. En este trabajo se miden y correlacionan los cambios en forma y tamaño del timo fetal, y se correlaciona su aspecto macroscópico con variaciones clínicas. Se estudiaron 80 fetos entre 14 y 21 semanas de gestación. El timo fue disecado conservando sus relaciones anatómicas más importantes. Observamos que la longitud de la glándula crece abruptamente entre la semana 17 y 18. Luego de la semana 18 el crecimiento en longitud de la glándula se mantiene de manera progresiva. El ancho del timo tiene un crecimiento notable entre la semana 15 y 16. El crecimiento total de la glándula, de la semana 14 a la 21, fue: 74,96% en su longitud, y 119,5% en el ancho. Analizando los datos obtenidos surge que el aumento de longitud y ancho del timo se acompaña del desarrollo anatómico del aparato cardiovascular y respiratorio respectivamente, en las mismas etapas, pudiendo confirmar que esto se deba a la relación existente entre la cápsula tímica, pleura y pericardio, que acompañan su crecimiento por arrastre. Destacamos el estudio de las dimensiones tímicas en el control prenatal, actuando como parámetro predictivo para la detección de patologías relacionadas con el sistema inmune y con patologías que afectan a otros órganos o sistemas relacionados. During the fifth week of gestation, appears the third branchial pouch that will migrate originating the thymus and the superior parathyroid glands. Thymus growth and development will continue after birth until puberty, and always occupying a cervico-thoracic position. In this study we show shape and size variations of fetal thymus, and the correlation between its macroscopic aspect and clinical variations. We studied 80 fetuses between 14 and 21 weeks of gestation. The thymus was dissected respecting the relationship with the main anatomical structures. We demonstrated that the gland length suddenly grows between the week 17th and 18th. After that length growth continues progressively. Thymus breadth evidently grows between the weeks 15th and 16th. General growth of the gland, between the weeks 14th and 21st was 74.96% in length and 119.5% in breadth. Considering these data it appears as evident that the increasing in length and breadth of the thymus is related to the anatomical development of the cardio-vascular and respiratory systems respectively, in the same stages, confirming the relationship between the thymus capsule, pleura and pericardium, that determines the morphology of this growth by “traction”. We emphasize the study of thymus measures in pregnant controls as a predictive parameter for the detection of pathologies associated to the immunological system and other related organs or systems.
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