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Biomedical subjects

Z Rychter

Publications and source records attributed to Z Rychter.

At least 37 records · Page 2Linked to original sources
PubMed1979

Formation of the heart loop and proliferation structure of its wall as a base for ventricular septation.

Controversial criteria for definition and classification of univentricular hearts are discussed from the point of view of proliferation pattern in the wall of heart tube and heart loop stage. The persistence of the primitive diffuse proliferation structure is the condition for the development of univentricular heart in which the morphogenetic mechanism forming the ventricular septum does not operate. Pseudouniventricular heart, i.e. the heart with the large main chamber accompanied by a small accessory cavity, is the result of total or partial right or left hypoplasia in which the extent of operation of the above mentioned mechanism is determined by the degree of ventricular hypoplasy. The morphogenesis of the heart wall structure and relief including the atrioventricular and arterial valves is a secondary feature, mostly dependent on the changed hemodynamic conditions.

Diagnosis, Differential↗
PubMed1978

Effects of isoprenaline and orciprenaline on the vascular bed of the mouse placenta.

High doses of isoprenaline or orciprenaline decreased the rate of transfer of tritium-labelled water from mother to fetus. The effect was blocked by propranolol. Maternal blood spaces of the placental labyrinth in the treated animals were congested with masses of red blood cells. These observations suggest that the placental circulation is impaired by high doses of beta-sympathomimetic drugs.

Animals↗
PubMed1977

Light and electron microscopy observations in the thyroid gland of the pheasant (Phasianus colchicus L.).

In the summer, the pheasant thyroid presents as a relatively quiescent organ with reduced secretory activity; the follicular epithelium is very low and mostly of the pavement type, while the follicles are unwontedly large and contain an increased amount of colloid. The follicular cell cytoplasm contains numerous characteristic spherical vacuolar structures. In the winter, however, the thyroid displays remarkable reconstruction and raised activity of the follicular cells, which are much higher and columnar; the small follicles contain less colloid. Peculiar rod-like or fusiform structures, some measuring up to 6,5 microgram, were observed in the cytoplasm of the follicular cells of both hen and cock pheasants in November and March. At the beginning of the winter (November), specific dark cells with pycnotic nuclei, evidently in process of degeneration, appeared in the follicular epithelium. In March, specific granulated cells (probably parafollicular cells) were found sporadically in the immediate vicinity of the wall of subcapsular follicles in cock pheasant.

Animals↗
PubMed1976

Quantitative development of choroid plexuses in chick embryo cerebral ventricles.

Quantitative development of choroid plexuses in cerebral ventricles of chick embryos was investigated by means of the planary projection of the choroid plexuses from the time the plexuses reached a consistent flattened structure. Choroid plexuses in the lateral cerbral ventricles were studied from day 6, the plexus in the third cerebral ventricle from day 8, and the plexus in the fourth cerebral ventricle from day 11 of incubation. Regardless of the microscopic origin of these choroid plexuses, their development reached a growth maximum on day 15 of incubation, after which there was a slight regression. The regression was gradual in the plexus of the third cerebral ventricle but a transient enlargement of plexuses in the laternal and in the fourth cerebral ventricle was observed between days 18 and 19. The enlargement of choroid plexuses in the lateral cerebral ventricles was caused by a flattening of the villi, whereas that of the plexus in the fourth cerebral ventricle was caused by thinning and yawning of the villi. The area of choroid plexuses in the lateral cerebral ventricles was six or seven times larger than the sum of the areas of the remaining choroid plexuses.

Animals↗
PubMed1976

Effect of hydrocortisone on the growth of choroid plexus and composition of cerebrospinal fluid in the developing chick embryo.

The effect of hydrocortisone on the telencephalic choroid plexus and on the osmolarity and ionic compositon of CSF was studied 48 hours after its administration onto the chorio-allantoic membrane of chick embryos on days 11 and 13 (20 mug per egg) or on day 17 (40 mug per egg). Hydrocortisone significantly reduced the choroid plexus area on days 13 and 15 but was ineffective on day 19. The topical analysis of these choroid plexuses, influenced by the steroid, pointed to a decrease of the growth activity in those parts whose proliferation was intensive. The transient population of villi in the apical part of these plexuses was the most sensitive. Those parts, being morphogenetically inactive or whose morphogenetic changes were not caused by the cellular proliferstion, were not affected significantly. The osmolarity of CSF increased significantly during the investigated period simultaneously with an increase in the sodium and chloride concentration while the concentrations of potassium did not change significantly. Hydrocortisone evoked a precocious increase in the osmolarity of CSF on days 13 and 15. Contemporarily, the potassium concentration in CSF was elevated while the steroid failed to change the sodium and chloride concentrations.

Animals↗
PubMed1975

Relations between development of the capillary wall and myoarchitecture of the rat heart.

The type of the blood supply to the myocardium appears to be closely related to its structural arrangement. The heart of adult poikilotherm animals is either entirely spongious, supplied from the ventricular cavity or its spongious musculature is covered by an outer compact layer with vascular supply. The size of the compact layer increases with increasing heart weight. The changes in the heart size during the ontogenetic development of honoiotherms are accompanied by the gradual transformation of the vascularless spongious musculature into a compact myocardium supplied thrugh coronary vessels. Up to the development of coronary arteries (in the rat up to the 17th day of embryonic life - ed) the myocardium is entirely spongious and supplied from mentricular cavity. Two types of primitive vascular bed are characteristic for this period: a) intertrabecular spaces, which penetrate deep into the ventricular wall as direct continuation of the endocardium, and b) intramyocardial clefts without endothelial lining. During further development of the terminal mascular bed, the outgrowth of endothelial cells into the myocardial clefts is important. The first capillaries with closed endothelial wall can be observed on the 18th ed. At this time various developmental stages o the terminal blood bed can be observed simultaneously. Within the following period (20-21 ed) the thick capillary walls become narrow and pericytes occur. The process of differentiation spreads in both ventricles and in septum from the base to the cardiac apex and is practically finished by the 14th day of postnatal life. The longitudinal orientations of myofibres starts between the 20th and 22nd ed. The final arrangement of muscle cells and capillaries into three layers (outer and inner longitudinal, central circular) is terminated during the second postnatal week.

Animals↗