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K Mollgård

Publications and source records attributed to K Mollgård.

16 recordsLinked to original sources
PubMed1975

Presence of a pineal nerve in sheep and rabbit fetuses.

The presence of a nerve located just caudal to the pineal gland in the midsagittal plane is demonstrated in sheep and rabbit fetuses. This nerve lies freely in the subarachnoid space and extends from the pineal gland to a region of the CNS located dorsal to the rostralmost part of the subcommissural organ (SCO). In rabbit fetuses the nerve is obsered on days 23 and 24 of gestation; we suggest that it is an ontogenetic equivalent to the pineal nerve of anuran amphibians. The developmental fate of the mammalian fetal pineal nerve is dicussed.

Animals↗
PubMed1975

Quantitative relationship between active sodium transport, expansion of endoplasmic reticulum and specialized vacuoles ("scalloped sacs") in the outermost living cell layer of the frog skin epithelium (Rana temporaria)

When an isolated frog skin (Rana temporaria) is exposed to a hydrostatic pressure difference between inside and outside bathing solutions (inside pressure higher than outside) of 20-50 cm of H2O and if under these conditions the skin is short-circuited electrically, small "vacuoles" appear light-microscopically in the outermost living cell layer in the epithelium. The number of such "vacuoles" shows a linear dependency on the rate of active sodium transport as measured by the short-circuit current. Electron-microscopically, the "vacuoles" are interpreted as previously undescribed organelles, the "scalloped sacs" which are about 0.5 mu in diameter, with a wrinkled surface and bounded by a unit membrane. This organelle is in intimate contact with sacs and tubules of smooth endoplasmic reticulum. The observed increase in the number of scalloped sacs usually is accompanied by a significant expansion of the whole system of endoplasmic reticulum. Some of the "vacuoles" seen light-microscopically must indeed be expanded cisternae of endoplasmic reticulum. The findings are discussed in light of the possibility that the scalloped sacs and the endoplasmic reticulum may be involved in active transport of sodium ions.

Animals↗
PubMed1975

Dendrodendritic gap junctions: a developmental approach.

Dendrodendritic gap junctions have been identified in the periaqueductal gray substance of adult rabbits and in the visual cortex of sheep fetuses. The introduction of Alcian blue as a marker substance facilitated the positive identification of gap junctions. Dendrodendritic contacts in the human fetal neocortex have been examined in freeze-cleaved specimens. The contacts are identified as gap junctions by their freeze-fracture appearance. Features of the developing dendrodendritic gap junctions are described. The possible significance of these contacts is discussed, and it is suggested that they provide electrotonic coupling of neurons belonging to the same columnar organization. In addition it is suggested that the dendrodendritic gap junctions of fetal neocortex participate in cell differentiation and morphogenesis of the cerebral wall.

Animals↗
PubMed1974

The ultrastructure of the carotid body in chronically hypoxic rabbits.

1. The ultrastructure of the carotid body in the rabbit has been examined by electron microscopy.2. A comparison was made between the ultrastructure of the carotid bodies in sea level rabbits, in rabbits which had been exposed to hypoxia equivalent to an altitude of 6000 m for 7 days and in rabbits which always had lived at an altitude of 4000-4300 m.3. We could not detect any difference in the ultrastructure between the two groups of hypoxic rabbits.4. When the hypoxic rabbits were compared with sea level rabbits there was a marked increase in the number of dense cored vesicles and mitochondria in the type I cells in the hypoxic rabbits. The Golgi region also appeared to be enlarged in the type I cells in the hypoxic rabbits.5. The finding suggests that in the rabbit the production of amines, probably dopamine, within the type I cells is increased during prolonged hypoxia which might explain the lowered ventilatory response to hypoxia observed in human high altitude residents.6. If the carotid bodies are organs of internal secretion the finding is compatible with an increased production of a hormone produced within the type I cells.

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