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Histología
La histología (del griego ι&=
#963;τÏŒς:
histós 'tejido' y
«-λογÎ¯α» -logía,
tratado, estudio, ciencia) es la ciencia que estudia todo lo
referente a los tejidos organicos: su estructura
microscópica, su desarrollo y sus funciones. La histología se
identifica a veces con lo que se ha llamado anatomía
microscópica, pues su estudio no se detiene en los tejidos, sino que=
va mas alla, observando también l=
as
células interiormente y otros corpúsculos, relacionand=
ose
con la bioquímica y la citología.
Las primeras investigaciones histológicas fueron posibles a partir <=
st1:place
w:st=3D"on">del
año 1600, cuando se incorporó el microscopio a los
estudios anatómicos. Marcello
Malpighi es el fundador de la histología y su nombre aún
esta ligado a varias estructuras histológicas. En 1665 se descubre la existencia de unidades
pequeñas dentro de los tejidos y reciben la
denominaciónde células. En&nb=
sp;1830,
acompañando a las mejoras que se introducen en
la microscopía óptica, se logra distinguir
el núcleo celular. En 1838 se introduce el
concepto de la teoría celular.
En los años siguientes, Virchow introduce el concepto de q=
ue
toda célula se origina de otra célula (omnis cellula ex cellu=
la).
El desarrollo tecnológico moderno de las herramientas de
investigación permitió un enorme a=
vance
en el conocimiento histológico. Entre ellos pode=
mos
citar a la microscopía electrónica,
la inmunohistoquímica, la técnica de hibridaci&oacu=
te;n
in situ. Las técnicas recientes sumado a =
las
nuevas investigaciones dieron paso al surgimiento de la biología
celular.
La histología jamas había tenido la importancia en el =
plan
de estudios de medicina y biología que ha alcanzado hoy día. =
La
histología es el estudio de la estructura microscópica del
be used to produce hydrogen or methane. In Chapter 7 “Waste to Renewable
Energy: A Sustainable and Green Approach Towards Production of Biohydrogen by
Acidogenic Fermentation”, Mohan provides a detailed review of the state of the
art with regard to biological hydrogen production using waste and wastewater as
substrates with dark fermentation processes. Many biological processes use
mixed cultures operating under non-sterile conditions (e.g. biological hydrogen
and methane production, as discussed above). Watanabe et al. in Chapter 8
“Bacterial Communities in Various Conditions of the Composting Reactor Revealed
by 16S rDNA Clone Analysis and Denaturing Gradient Gel Electrophoresis” demonstrate
the utility of 16S rRNA analysis and denaturing gradient gel electrophoresis
(DGGE) techniques for tracking microbialcommunities within a mixed and changing
culture. Their work uses a composting process, which offers a typically
cost-effective alternative to incineration for the remediation of contaminated
soil. The production of liquid fuel from biomass necessitates the consideration
of various issues such as the effects on the food supply, the rainforest, and
greenhouse gas production, as well as carbon sustainability certiï¬cation.
Some of these issues may require appropriate regulations and in Chapter 9
“Perspectives on Bioenergy and Biofuels”, Scott et al., examine these issues
closely. In addition to its environmental advantages, the use of renewable
energy resources offers the potential for stimulation of the economies of the
nations where they are produced. The potential products of these renewable
materials extend well beyond liquid fuels alone. Owing partly to the enormous
volume of their production, fuels are sold for relatively low prices, and the
successful implementation of renewable fuels depends, at least initially, on
their ability to compete in the marketplace. To this end, it is particularly
important to maximize the efï¬ciency of their production in bioreï¬neries
where secondary products would be derived from the same feedstock as the fuels.
As an example, petroleum reï¬neries have been in operation for over 150 years
and now produce lubricants, plastics, solvents, detergents, etc., all from the
starting crude oil [6]. Similarly, biomass, in addition to being used for the
production of fuels, can be used as a starting material for the production of
other value-addedproducts of microbial bioconversion processes such as
fermentable sugars, organic acids and enzymes. In Chapter 10 “Perspectives on
Chemicals from Renewable Resources”, Scott et al. describe how, with the aid of
biotechnology, Protamylase R generated from starch production, can be used as a
medium for the production of a cynophycin polymer, which is a major source of
arginine and aspartic acid for the production of many industrially useful
compounds including 1 -butanediamine and succinic
acid. In Chapter 11 “Microbial Lactic Acid Production from Renewable
Resources”, Li and Cui describe the production of lactic acid from renewable
resources such as starch biomass, cheese whey etc. Lactic acid has recently
gained attention due its application to the manufacture of biodegradable
polymers. Among other renewable resources, Chapter 12 “Microbial Production of
Potent Phenolic-Antioxidants Through Solid State
Fermentation”, Martin et al. describe the role of agroindustrial residues
including plant tissues rich in polyphenols for the microbial bioconversion of
potent phenolics under solid state
fermentation conditions. Hence, combined with the economy of scale derived from
large reï¬neries, secondary products could be key to
bridging the price gap between fossil fuels and renewables. One critical
advantage of biofuels is their potential to achieve a reduction in greenhouse
gas releases, since the plants from which they are produced derive their carbon
from the atmosphere. The overallbalance of greenhouse gases however, depends in
large measure on the particular feedstocks used and the methods by which they
are produced. Corn ethanol for instance, while being potentially carbon neutral,
is not likely to achieve an overall reduction in greenhouse gas release due to
its requirement for nitrogenous fertilizer and the associated release of
nitrous oxide [7]. An interesting approach to the production of biodiesel is
the use of algae to synthesize oil from the CO2 they capture for growth. Algae
cultivation offers a potential low-cost alternative to physical methods of
carbon sequestration such as pumping liquid CO2 underground or underwater or
chemical methods such as base-mediated capture of CO2 and subsequen
material biológico y de la forma en que se relacionan tanto estructu=
ral
y funcionalmente los distintos componentes individuales. Es crucial para la
medicina y para la biología porque se encuentra en las intersecciones
entre la bioquímica, la biología molecular y
la fisiología por un lado y
los procesos patológicos y sus consecuencias por el otro.<=
br>
Los histólogos prestan cada día mayor
atención a los problemas químicos. Así por ejem=
plo,
cunde entre ellos la aspiración a determinar con exactitud la
composición química de determinadas estructuras de la masa vi=
va,
al estudiar las enzimas, iones, proteínas, hidratos de
carbono, grasas y lipoides, fermentos, etc. en las células y en
los tejidos con el auxilio del microscopio
