Digitum Colección:
http://hdl.handle.net/10201/17710
2024-03-29T13:19:42ZEffects of chronic low-level copper exposure on ultrastructure of the olfactory system in rain bow trout (Oncorhynchus mykiss)
http://hdl.handle.net/10201/18454
Título: Effects of chronic low-level copper exposure on ultrastructure of the olfactory system in rain bow trout (Oncorhynchus mykiss)
Autor/es principal/es: Julliard, A.K.; Saucier, D.; Astic, L.
Resumen: This study investigated the effects of
a chronic exposure to a low level of copper on
cell populations of the olfactory system in yearling
rainbow trout. Fish were sacrificed after 15, 30 and
60 days of copper exposure. Transmission electron
microscopy was used to describe the sequence
of subcellular changes occurring in three tissues,
the sensory epithelium, the olfactory nerve and
the olfactory bulb. Data show that a 15-day exposure
to 20 pg/l of copper causes specific degeneration of
al1 mature receptor cells as well as numerous immature
neurons. Moreover, degenerating receptor cells exhibited
morphological features of a cell death by apoptosis.
After 30 days, and more specifically after 60 days
of exposure, numerous clusters of cells were observed
in the basa1 region of the epithelium, suggesting a
great mitotic activity in this area. In parallel, an
increased number of maturing receptor cells and
goblet cells were observed, but no fully mature
neurons were noted even after 60 days of exposure. In
both the olfactory nerve and the olfactory bulb, the
number of degenerating axons and terminals, which was
high at 15 days, decreased with time and some process
of glomerular reinnervation was detected after 60 days. A reactive hypertrophy of supporting, ensheathing
and astrocytic cells was also observed in exposed
fish, which demonstrates that these cell types
are actively involved in the process of tissue scarring.
Even though some signs of neurona1 regeneration
were reported during the time-course of exposure,
indicating some fish acclimation, results raise the
question of the olfactory function during such
environmental stress.1993-01-01T00:00:00ZStructural and ultrastructural study of the Meissner plexus in amphibians, Rana temporaria
http://hdl.handle.net/10201/18453
Título: Structural and ultrastructural study of the Meissner plexus in amphibians, Rana temporaria
Autor/es principal/es: Fernández Alvarez, B.E.
Resumen: A study of the submucous, periglandular and
intravillous plexus of the frog has been carried out with
light microscopy and conventional electron microscopy.
The existence of a true Meissner plexus, with light
microscopy, as well as the existence of sensitive-like
structures, with light and electron microscopy have been
demonstrated in the frog.1993-01-01T00:00:00Z«Neuroendocrine» differentiation in hepatocellular carcinomas (HCCs): lmmunohistochemical reactivity is related to distinct tumor cell types, but not to tumor grade
http://hdl.handle.net/10201/18452
Título: «Neuroendocrine» differentiation in hepatocellular carcinomas (HCCs): lmmunohistochemical reactivity is related to distinct tumor cell types, but not to tumor grade
Autor/es principal/es: Zhao, M.; Laissue, J.A.; Zimmermann, Astrid
Resumen: We have analyzed neuroendocrine
differentiation (ND) in hepatocellular carcinomas
(HCCs) of fifty patients. It turned out that ND is
frequent in HCCs, and that it is not restricted to
fibrolamellar hepatocellular carcinoma (FL-HCC).
Multiexpression is seen in a quarter of the cases, and
marker coexpression may occur within the same tumor
cell. ND predominates in trabecular and rnixed HCCs,
but does not appear to be related to grade. Most positive
cases showed a hepatocyte-like cell morphology,
frequently associated with bile formation. It thus appears
that the HCC cell type most likely to show ND is a
hepatocyte-like one, i.e. differentiated cell, frequently
polarized and producing bile, rather than a small and
poorly-differentiated cell. Possible pathogenic
mechanisms leading to ND in HCCs are briefly
discussed.1993-01-01T00:00:00Zlmmunohistochemical characterization of transplantable rat squamous cell carcinoma (FF-6) in skin and thymus
http://hdl.handle.net/10201/18451
Título: lmmunohistochemical characterization of transplantable rat squamous cell carcinoma (FF-6) in skin and thymus
Autor/es principal/es: Fujikura, Y.; Inoue, T.; Sawada, T.; Tokuda, N.; Fukumoto, T.
Resumen: FF-6 is a transplantable squamous cell
carcinoma which originally arose in the facial skin of a
DA rat. It was established after maintaining the tumor in
the subcutaneous tissue or peritoneal cavity of DA rats
conventionally for over 30 generations. When the
soybean-sized original FF-6 tumor was transplanted
subcutaneously, it became an oval, hard, whitish, solitary
and thumb-head-sized nodule within one month. After
intraperitoneal transplantation of FF-6, it formed many
nodules ranging from miliary to thumb-head size, which
adhered andlor metastasized to many abdominal organs.
When FF-6, cut into small pieces, was injected into the
lower lip, the tumor grew bigger in situ, and
metastasized to regional lymph nodes. Histologically,
FF-6 was characterized as a well-differentiated
squamous cell carcinoma, showing positive staining with
anti-keratin, anti-laminin, anti-collagen type IV, antifibronectin
and UB- 14 antibodies.
This transplantable tumor may be useful for
analyzing the mechanisms of proliferation and
metastasis of squamous cell carcinoma in vivo, and the
host defence mechanism in rats, as well as being a
suitable model of human squamous cell carcinoma.1993-01-01T00:00:00Z