1,721,121 research outputs found
Metodi di macerazione per l'esposizione di strutture subcellulari per lo studio al microscopio elettronico a scansione
No full textFine Structural Markers of Human Oocyte Quality in Assisted Reproduction
No full textAfter completing its maturation, the human oocyte acquires very peculiar
fine structural features. In this review we describe by LM, TEM and SEM the
nuclear and cytoplasmic changes, as well as the changes in the texture of the
ZP, occurring in the human oocyte during the final stages of maturation. Oocytes
were obtained during ART cycles and destined to morphological evaluation after
the informed consent of the patients. The critical analysis of the data reviewed
leads us to emphasize that: 1. Both the completion of the maturative changes
in the preovulatory period and the absence of degenerative alterations in the
cytoplasmic microdomains of the human mature oocyte ultimately render the
female gamete competent for fertilization; 2. Several minute cellular aberrations,
detectable only by electron microscopy analysis, may occur in the human
oocyte as the consequence of the application of ART protocols (IVM and
cryopreservation, in particular) and could be responsible for ART failures, even
affecting early embryo development.
Keywords: Oocyte; Assiste
La zona pellucida (ZP) in follicoli in sviluppo ed atresici del topo. Studio ultrastrutturale con l'uso del rosso rutenio e del Triton X100
No full textCellular and microvascular changes of the ovarian follicle during folliculogenesis: a scanning electron microscopic study
No full textIn order to study the three-dimensional topographic arrangement of the oocyte and
zona pellucida, follicular cells and follicle microvasculature, this study
applied alkali maceration methods for tissue exposure, the ruthenium
red-detergent method for the extracellular matrix visualization, and the vascular
corrosion cast technique to rabbits, guinea-pigs and mice ovaries at different
stages of follicular development. Macerated samples showed a gradual
differentiation of the oocyte surface. This, in primordial follicles, appeared
rather smooth, but, with the follicular development, displayed a gradual increase
of blebs and microvilli. The latter widely covered the surface of oocytes
contained in large or mature follicles. The outer surface of the zona pellucida
showed numerous fenestrations, whereas the inner one was smooth. The ruthenium
red-detergent method permitted a well detailed view of the filamentous texture of
the zona pellucida. The three-dimensional distribution of the contacts between
oocyte and neighbouring follicular cells was clearly evaluated in macerated
samples. Follicular cells of primary follicles were characterized by their short
cytoplasmic processes reaching the oocyte surface. In secondary follicles, these
processes issued secondary processes. In larger follicles, the secondary
processes of the corona cells were much longer and thinner, and took a tortuous
course to reach the oocyte surface, which ran among the numerous oocyte
microvilli. This microvillous arrangement greatly increases contact between the
oocyte and corona cells, and suggests a coordinated reciprocal control of the
activities of both cell types. These data also showed that the spongy and
filamentous nature of the zona pellucida is closely dependent upon the temporal
differentiation and enormous increase in number of follicular cell projections
and their ramifications. Maceration revealed the theca cells surface. In smaller
follicles these appeared as fusiform cells which resembled fibroblasts. In larger
or mature follicles, many theca cells differentiated to possess morphological
features of steroidogenic cells. In addition, these cells delimited a series of
intercellular communicating lacunae, continuous with wide pericapillary spaces.
The gradual differentiation of the follicle towards a structure having an
endocrinal role was further emphasized in vascular corrosion casts. A simple
microvascular net made of thin capillaries supplying primary follicles was seen
to transform into an elaborate sinusoidal network made of thick permeable
capillaries, supplying mature follicle
Sulla presenza di 'ponti trasversali intrasinusoidali' nel fegato di Praomys. Studio ultrastrutturale
No full textSaponin, ruthenium red, osmium-thicarbohidrazide and high resolution scanning electron microscopy in the study of the extracelullar matrix and mucus
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