Search PubMed⌕ Search

Biomedical subjects

A Hansen

Publications and source records attributed to A Hansen.

At least 217 records · Page 12Linked to original sources
PubMedDate not supplied

Ultrastructure of the olfactory epithelium in intact, axotomized, and bulbectomized goldfish, Carassius auratus.

The ultrastructure of the olfactory epithelium in intact, axotomized, and bulbectomized goldfish was studied by scanning and transmission electron microscopy. A total of 58 adult goldfish of various survival times were examined to determine whether the different types of surgery--either olfactory nerve transection or bulbectomy--yielded differences in the extent or time course of cellular degeneration and renewal. Control animals were also examined in detail to elucidate previous controversial findings concerning the types of olfactory receptor neurons present in goldfish. We found that the intact olfactory epithelium of unoperated control goldfish contains the previously observed ciliated and microvillous receptor neurons, and the crypt cell, a cell type not yet seen in the goldfish but recently reported in other species of teleosts. Following either olfactory nerve transection or bulbectomy, the olfactory receptor neurons showed similar signs of degeneration and subsequent cell death, but, surprisingly, the thickness of the olfactory epithelium did not change significantly with either treatment. The time course of receptor cell renewal was different in axotomized and bulbectomized goldfish. In axotomized goldfish, the amount of receptor cells decreased continuously until 8-13 days after surgery, followed by rapid cell renewal. For bulbectomized goldfish, cell replacement began almost immediately after surgery, with degeneration and cell renewal occurring simultaneously. Six weeks after bulbectomy, cell death and cell proliferation reached a "steady state," and the epithelia did not further improve.

Animals↗
PubMedDate not supplied

Refugee dynamics: Angolans in Zambia 1966 to 1972.

"The following study of Angolan refugees in Zambia examines the decision-making dynamics of refugee movements, documents a case of extensive self-settlement, describes the background to the refugee movement, and briefly compares the welfare of self-settling refugees and those who are in government schemes."

Africa↗