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Biomedical subjects

M Doskocil

Publications and source records attributed to M Doskocil.

At least 55 records · Page 3Linked to original sources
PubMed1978

Development of spontaneous motility in chick embryos supraspinal control.

Changes in spontaneous motility were studied in 11- to 19-day-old chick embryos after acute and chronic decapitation. Chronic decapitation was performed on the 2nd day of incubation, at stage 11--14. Up to the 15th day, acute decapitation merely reduced the frequency of spontaneous movements. In 17-day embryos it was followed by typical spinal shock, with transient complete disappearance of spontaneous movements of the embryo. The duration of spontaneous motor depression was proportional to the age of the embryo. After the 15th day of incubation, spinal decentralization changed continuous to discontinuous motor activity, with spontaneous paroxysms of high amplitude movements followed by long intervals of motor rest. Chronic decapitation was manifested, from the 15th day of incubation, in significant reduction of spontaneous movement frequency and again in discontinuous motility. A microscopic anatomical analysis of the spinal cord of decapitated embryos showed defects of the tracts in the lateral and ventromedial area of the cord and degenerative injury of the motoneurones in the ventral horns. Supraspinal control thus does not begin to act effectively on the spontaneous motility of chick embryos until about the 15th day of incubation. Supraspinal factors modulate both the frequency and the rhythm of spontaneous movements and are evidently also indispensable for normal morphological development of the spinal cord motor apparatus of chick embryos.

Animals↗
PubMed1978

Increase in volume of the chick wing bud at the beginning of its development.

Serial sections in the transverse body plane were used to determine the volume of the limb bud and of its parts--namely, the apical ectodermal ridge, the ectodermal epithelium, the coat zone, the vascular zone, and the plug during the period between the onset of its formation (Hamburger and Hamilton's stage 17) and the stage of nerve fibre ingrowth (HH 22 +). During that period the anlage of the wing was shown to increase in volume, mainly by increasing in length, with the increase being more than 8 times during a 28 hr incubation. Various components differed in their growth rate. The apical ectodermal ridge did not increase at all. The part that increased most--48 times--was the plug which gives rise to the cartilaginous primordium of the skeleton of the wing. The proportions of the various zones changed markedly during growth.

Animals↗
PubMed1976

The "stright-jacket" syndrome in chicks. II. Mechanism of development.

In a longitudinal study including measurement of the pressure in the amniotic cavity, amniotomy, and planimetric evaluation of the size of the amniotic sac, we investigated the development of the "strait jacket" syndrome in White Leghorn chicken embryos injected intraamniotically (ia) or paraamniotically on the fourth day of incubation with histone or embryotoxic serum, with the following results. Hyperlordosis and eventration developed as an outcome of tonic contraction of the amnion, which was observed only three hours after ia administration. Contraction of the amnion caused elevation of the intraamniotic pressure, which, 12 hours after ia injection, attained a mean value of 22.4 Pa (2.3 mm H2O). This value was not only significantly higher than the mean for control embryos (3.9 Pa), but it was critically close to the mean fluid pressure in the brain vesicles. Loss of the latter overpressure caused the vesicles to collapse, and the walls shriveled and exencephaly developed. Paraamniotic injection was not followed by either contraction of the amnion, or significant increase in intraamniotic pressure. This did not prevent heart malformations and cranioschisis of various extent. The majority of cardiovascular malformations were probably the hemodynamic consequence of overfilling of the intraembryonic vascular bed, which was one of the early signs of the effect question. Cranial-vault defects can be causally associated with the formation of amnionic adhesion and fusion with the epidermal ectoderm. This observation stresses the significance of the embryonic membranes and the fluid pressures within them for the development of certain congenital deformities and concentrates attention on teratological study of substances that induce protracted contraction of smooth muscle.

Abnormalities, Drug-Induced↗