Biomedical subjects

J Rickenbacher

Publications and source records attributed to J Rickenbacher.

3 recordsLinked to original sources

PubMed1979

The development of cholinergic ganglia in the chick embryo heart.

Cholinesterase activity was investigated in the heart of the developing chick from the 6th to 20th day of incubation. The earliest cholinesterase-positive nerve cells and fibers could be demonstrated between the 7th and 9th day. On the 13th day the nervous structure attained full development comparable with that seen in the hatched chicken. The number of ganglia increases up to the 15th day, and remains constant thereafter. The right ventricle is associated with the largest number of ganglia.

Animals↗

PubMed1976

[Circulatory disturbances in the embryo (author's transl)].

Circulatory disturbances in human embryo in the phase of organogenesis are frequent, as shown by the pathological-anatomical findings and the results of experimental embryology. There is edema and hemorrhage around the blood vessels and emboli of necrotic tissue (chiefly from the chorion) are found. The embryonic heart, which shows peristaltic movements, has a very small reserve of performance. Since there is no peripheral regulation of circulation, every damage to the vascular system results in a higher cardiac load. During organogenesis the extraembryonic vascular plexus is considerably larger than the intraembryonic plexus. Lesions of the chorion, the barrier between embryo and environment, can result in chronic or acute cardiac insufficiency. This is presumably one of the reasons why the mortality in this developmental stage is particularly high.

Cardiovascular Diseases↗

PubMed1975

[Functional changes in embryonal heart].

Intracardiac pressure in the developing chick was measured throughout the embryonic and fetal period. Amplitude and heart rate were used to estimate cardiac output and power of the heart. In addition, the cardiac performance per milligram dry weight was calculated. Initially, the cardiac tube displays a peristaltic movement which results in a continuous pressure within the vascular lumen. Switch to rhythmic atrial and ventricular contractions occurs between the 6th and the 9th developmental day. This change is directly correlated with differentiation of the conduction system. The simultaneous formation of the cardiac septa and valves is of only minor importance for this change in function. Between the 4.5th and 5.5th day, functional development is found to halt temporarily. This could be due to the enormous growth of the extra-embryonic vascular network. During this period, the risk of damage to the embryo by endogenous or exogenous factors is highest. In the human embryo, this developmental stage corresponds to the period between the 28th and 34th day. After this change in function the heart is able to build up a reserve of power, since it has less work to perform per unit weight.

Animals↗