[Cervical spondylosis, cervical neurology and thoracic syndrome].
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Adult↗
Biomedical subjects
B Lefèvre
Publications and source records attributed to B Lefèvre.
Lead accumulation in the mouse ovary after treatment-induced follicular atresia.
Although the main target of lead (Pb) toxicity is the red blood cell, Pb-associated changes in the nervous system, the kidney, and the reproductive system have also been described. The few Pb studies conducted on females revealed mostly miscarriages, premature delivery, and infant mortality in humans and animals. This study was done to correlate Pb accumulation in the ovary with damage to folliculogenesis. Pb burden was assayed by atomic absorption spectrometry in bone, liver, adrenal glands, ovary, and fetuses taken from mice exposed according to 2 protocols: intraperitoneal (i.p.) injection of Pb(NO(3))(2) 10 mg/kg/day for 15 days or 10 mg/kg/week for 15 weeks. Ovaries were examined histologically. Pb accumulation in the various soft tissues of acutely exposed mice was similar, and significantly higher than in the organs of chronically exposed mice. A low Pb concentration in the ovary caused dysfunction of folliculogenesis, with fewer primordial follicles and an increase in atretic antral follicles.
Adrenal Glands↗
The germinal vesicle of the mouse oocyte contains elements of the phosphoinositide cycle: what is their role at meiosis resumption?
The role of the nuclear phosphoinositide (PI) cycle during meiotic resumption in mouse oocytes was examined. First, using indirect immunofluorescence staining with specific monoclonal antibodies (mAbs) against elements of this cycle, the presence of inositol trisphosphate receptors (IP3Rs) (IP3R-1 or IP3R-3) or phosphoinositide-phospholipase (PLC) isoforms (PLC beta 1 or PLC gamma 1) was monitored in the germinal vesicle (GV). Using confocal laser scanning microscopy, we analysed the effects of the nuclear microinjection of these antibodies on both spontaneous nuclear calcium oscillations and meiosis resumption. Immunostainings showed that IP3R-1 and PLC beta 1 isoforms were both present in the GV, whereas IP3R-3 and PLC gamma 1 isoforms were not. The anti-IP3R-1 mAbs or the anti-PLC beta 1 mAbs microinjected into the GV, induced inhibition of both the nuclear Ca2+ oscillations and the meiotic process, whereas the anti-IP3R-3 mAbs and the anti-PLC gamma 1 mAbs did not. We concluded that a specific nuclear PI cycle is present in the mouse oocyte and meiosis resumption requires a specific nuclear phosphoinositide-dependent Ca2+ signal.
Animals↗
[Oocyte maturation. From animal experiments to human reproduction techniques].
The control of the oocyte growth and maturation are complex processus implicating endocrines (gonadotropines) and paracrine factors (growth factors, cytokines, steroids...), the paracrine regulation being under the endocrine control. The control of the cytoplasmic and nuclear maturation is realized by substances going through gap junctions from the follicular cells to the oocyte. Two of these substances, which are present in the follicular fluid, are responsible for maintaining the meiotic arrest: cyclic AMP and purines. Hormones or growth factors, which are able to affect the oocyte maturation both in vivo and in vitro, when they interact with their receptors stimulate enzymes which in turn stimulate the release of second messengers. Actually, the whole process that is oocyte maturation followed by fertilization in vitro does not give good results. This difficulty does not permit yet the freezing of immature oocytes which could be a solution in some cases encountered in Medically Assisted Procreation.
Animals↗