Histological analysis of an alkaline based tissue clearing technique for fetal musculoskeletal tissue / Análisis histológico de una técnica de limpieza de tejido de base alcalina para tejido musculoesquelético fetal

SUMMARY: Tissue clearing techniques are frequently used in the observation and description of anatomical structures and pathways without altering the three-dimensional layout of the anatomical specimen. Tissue optical clearing promotes preservation of three-dimensional structures, which allows the study of the internal anatomy in its original position and original spatial interaction. Among these techniques, Potassium Hydroxide (KOH) maceration clearing is one of the most widely used. However, the histological changes of tissue after KOH maceration have yet to be fully understood. Our aim is to describe the microscopical differences between macerated and normal tissue. To better understand said changes, two human fetuses with a gestation period of 16 to 28 weeks were cleared and processed for histological analysis. Microtome slides of the fetuses' lower limbs were obtained and stained with Hematoxylin & Eosin, Periodic Acid Schiff (PAS), and Masson's trichrome with the purpose of observing the histological and macromolecule composition changes in cleared tissue. Remarkable differences at a histological level regarding the composition of the cellular structures, since diaphanized tissues showed a predominance of extracellular matrix composed of collagen fibers with the absence of most of the nucleated cellular tissue. Phospholipid's saponification, nucleic acids degradation and a change on proteins structural properties are the main factors inducing clearing. At the same time, molecular stability of collagen in alkaline conditions allows the specimen to maintain its shape after the process.

RESUMEN: Las técnicas de limpieza de tejido se utilizan con frecuencia en la observación y descripción de estructuras y vías anatómicas sin alterar el diseño tridimensional de la muestra anatómica. El aclaramiento óptico de tejidos promueve la preservación de estructuras tridimensionales, lo que permite el estudio de la anatomía interna en su posición original y la interacción espacial original. Entre estas técnicas, el aclarado por maceración con Hidróxido de Potasio (KOH) es una de las más utilizadas. Sin embargo, los cambios histológicos del tejido después de la maceración con KOH aún no se han entendido por completo. Nuestro objetivo es describir las diferencias microscópicas entre el tejido macerado y el normal. Para entender mejor dichos cambios, dos fetos humanos con un período de gestación de 16 a 28 semanas fueron aclarados y procesados para análisis histológicos. Se obtuvieron microtomos de las extremidades inferiores de los fetos y se tiñeron con hematoxilina y eosina, ácido peryódico de Schiff (PAS) y tricrómico de Masson con el fin de observar los cambios histológicos y de composición de macromoléculas en el tejido aclarado. Diferencias notables a nivel histológico en cuanto a la composición de las estructuras celulares, ya que los tejidos diafanizados mostraban un predominio de matriz extracelular compuesta por fibras de colágeno con ausencia de la mayor parte del tejido celular nucleado. La saponificación de los fosfolípidos, la degradación de los ácidos nucleicos y un cambio en las propiedades estructurales de las proteínas son los principales factores que inducen la depuración. Al mismo tiempo, la estabilidad molecular del colágeno en condiciones alcalinas permite que la muestra mantenga su forma después del proceso.

Some macro and trace elements in various tissues of Van fish variations according to gender and weight / Alguns macro elementos e traços em vários tecidos de variação de peixe Van de acordo com sexo e peso

Van fish is a fish that can live in soda water at pH 9-10. Van fishing area is a very important source of protein for the people. The variations in tissue metal levels according to gender and weight in Van fish (Alburnus tarichi, Güldenstadt 1814) were studied. This study was conducted for the first time in Van fish. Which it is very important for living organisms Calcium(Ca), magnesium(Mg), sodium(Na), potassium(K), cobalt(Co), chromium(Cr) and lithium(Li) elements levels in the muscle, liver, gill, gonad, and brain tissues of Van fish were investigated by using inductively-coupled plasma-optic emission spectroscopy (ICP-OES). The results were evaluated in two groups as macro-elements(Ca, Mg, Na, K) and trace-elements(Co, Cr, Li). Cobalt concentration in brain tissue was found to be higher than those in other tissues. Also, male fish had higher metal concentrations than female fish and their metal levels in brain and gonad tissues varied with their weight (P<0.05). This study shows that consumption of Van fish can be consumed to supply some necessary minerals required for a healthy nutrition.(AU)

Peixes van são a única espécie de peixe vivendo em pH 9-10 no mundo. A área de pescaria Van é uma fonte importante de proteína para a população. As variações de niveis de metal nos tecidos de acordo com sexo e peso do peixe Van (Alburnus tarichi, Güldenstadt 1814) foram estudadas. Esse é o primeiro estudo conduzido com peixes Van. São importantes para organismos vivos o Calcio (Ca), magnésio (Mg), sódio (Na), potássio (K), cobalto (Co), cromio (Cr), e lítio (Li) e foi investigado o nível desses elementos no músculo, fígado, brânquia, gônada, e tecido cerebral dos peixes Van utilizando espectrometria de emissão atômica por plasma acoplado indutivamente (ICP-OES). Os resultados foram avaliados em dois grupos como macro-elementos (Ca, Mg, Na, K) e traços (Co, Cr, Li). Concentração de cobalto em tecido cerebral foi mais alto que em outros tecidos. Peixes machos tinham concentração mais alta de metais que fêmeas e os níveis de metal no cérebro e gônadas variava com seu peso (P<0.05). Esse estudo mostra que o consumo de peixe Van pode suplementar alguns minerais necessários para uma nutrição saudável.(AU)