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Biomedical subjects

A Clavert

Publications and source records attributed to A Clavert.

At least 55 records · Page 3Linked to original sources
PubMed1979

The use of avian double monsters in studies on induction of the nervous system.

Ninety-eight duck double monsters (siamese twins) were studied between 48 and 72 h of incubation in whole-mount or serial-sectioned preparations. Each case was classified into one of four categories depending on the orientations of the two embryonic axes. In all classes, defects in primary neural induction of various parts of the embryonic nervous system were observed which depended to a large extent on the distance separating the anterior tips of the two notochords or on the relative positions of the notochords. Our observations suggest that: when the same inducing field of one embryo overlaps to a critical extent with that of the twin, the two inducers act as one; induction of forebrain and optic vesicles is purely prechordal; the notochord exerts an inhibition on induction of forebrain by prechordal mesoderm; and the presence of rhombencephalic structures depends on both prechordal and chordamesodermal interactions.

Animals↗
PubMed1978

[Study of the formation and the normal and pathological evolution of the eye neural primordium (author's transl)].

The analysis of duplicate embryos, cyclops and colobomic fissure defects show that: 1. - optic vesicle and colobomic fissure are inducted by the prechordal plate. The combined inductive influence of prechordal plate and notochord carry eye absence out; 2. - initial failure of the colobomic fissure is always associated with retina folds and produce lens, vitreous and optic nerve anomalies; 3. - colobomic fissure is one indispensable anatomic structure to the optic fiber migration from the retina to the optic pedicle. Retina cutting in 4 days old chick embryos determine the disappearing of the pedicle cells. Contact between the optic fiber and the pedicle cells determine the glial cells differentiation. The colobomic fissure is a very important period of the eye evolution and the eye organisation.

Animals↗
PubMed1978

Abnormalities resulting from intra-adnexal injection of glucose in the rabbit embryo--an experimental model of "amniotic disease".

Intra-adnexal injections of glucose into the rabbit embryo have induced amputations of digits or segments of limbs, congenital grooves, amniotic bands, club feet, syndactyly, hare lip, anencephaly, and ulcerations of the scalp. We have thus reproduced all the anomalies which are encountered in the clinical syndrome of "amniotic disease." These anomalies result from destruction of the cutaneous epithelium and the subjacent mesenchymatous cells, and extravasation of blood with hematoma formation around the superficial vessels. This general mechanism explains most of these anomalies. Intra-adnexal injections of glucose thus constitute an external trauma for the embryo and is good experimental model of amniotic disease.

Abnormalities, Drug-Induced↗
PubMed1977

[Reduction of glucose embryotoxicity by intra-ovulary injection of insulin].

The injection of 10 mg glucose and 0.4 U.I. of insulin in the ovulary fluid of 14th day rabbit embryo, produces less anomalies than the injection of the same concentration of glucose alone. This result shows that the insulin receptor is probably present in the 14th day rabbit embryo, before the differentiation of B cells in the pancreas.

Abnormalities, Drug-Induced↗
PubMed1977

[Congenital cystic dilatation of biliary tract (author's transl)].

The congenital cystic dilatation of biliary tract is un frequent affection and there are many types described (classification of Alonso Lej). The authors present the observation of a little girl of 12 years who presented a complete cystic dilatation ob biliary tract, diagnosed before the operation by intravenous biligraphy. This association of intra and extra hepatic cystic dilatation has been described in 1964 by Arthur and Stuart, and the diagnosis is to be done by intraveinous biligraphy in 30% of cases.

Bile Ducts↗
PubMed1976

[Period of sensitivity of the rabbit fetus to the embryopathic and lethal action of D-glucose in intraovular injection].

We studied the effect of injection of D-glucose in rabbit foetus ovulary liquid at the 14th, 16th and 18th day of pregnancy. Injection of 14th and 16th day determined a high percentage of foetal death and limb necrosis. On and after the 18th day of pregnancy, the foetus is insensible to the treatment. The 18th day is, in the rabbit, the period of a new hormonal equilibre establishment.

Abnormalities, Drug-Induced↗
PubMed1976

[Effect of short-term cyclophosphamide administration on rabbit sperm].

Daily injection in the rabbit of 60 mg cyclophosphamide, during four days, product during 8 to 9 weeks one importance decrease of the number and the mobility of the ejaculated spermatozoa. This interval correspond with the spermatogenesis and epididymal transit period. Low doses injections product only one mobility decrease.

Animals↗
PubMed1975

[Teratospermia and migration of spermatozoa in vitro and in vivo].

The comparative study of morphological anomalies of spermatozoon before and after penetration shows that in vivo or in vitro migration causes a selection of the spermatozoon. This selection is not complete. Anomalies of the midpiece or of the flagella inhibe the spermatozoon progression but morphological anomalies of the head are not a handicap for the migration. this observation seems to indicate that spermatozoa with chromosomic failures can paticipate to the fertilization.

Congenital Abnormalities↗
PubMed1975

[Tetratospermia and chromosome abnormalities].

Human semen in two chromosomal abnormalitie cases presents one important increase of small, large and double head spermatozoa. Findings of this type of abnormal sperm morphology must be include chromosome analysis in the subfertile couple investigations.

Chromosome Aberrations↗