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Biomedical subjects

J Ballarino

Publications and source records attributed to J Ballarino.

4 recordsLinked to original sources
PubMed1986

Studies of otoconial development in a "giant-crystal" strain of chicks using scanning electron microscopy, polarized light microscopy, and X-ray crystallography.

Otolith formation was studied in a mutant strain of low-fertility Delaware chicks which exhibit an otolithic defect. In all chicks of this strain, otoliths were present as a fused crystal mass which contained abnormally large (giant) otoconia. Studies of the formation of such otoliths during embryonic development revealed that from the very earliest stages the otoconia were much larger than normal, and in the saccular and utricular otoliths formed a fused mass. These results are interpreted as supporting a hypothesis of the de novo formation of giant otoconia in this giant-crystal strain as opposed to the recrystallization hypothesis proposed for other, dissimilar mutant mammals and birds which also produce giant otoconia.

Animals↗
PubMed1985

Studies of otoconia in the developing chick by polarized light microscopy.

Using polarized light microscopy we were able to observe the mineralization patterns of embryonic and neonatal chick otoconia. We compared preparations of freshly dissected material spread under mineral oil to material that had been treated with various fixatives and dehydration agents. We found that the standard fixation agent, glutaraldehyde, and some immersion oils etched embryonic chick otoconia but that fixation with 70% acetone or 70% alcohol followed by dehydration to 100% acetone or 100% alcohol left the otoconia intact. The size and shape of freshly dissected chick otoconia observed with polarized light microscopy were similar to those of acetone-fixed, critical-point-dried material examined by SEM. Embryonic forms of otoconia were found to have a fluted pattern that was different in morphology from otoconia found in hatched chicks and adults. Embryonic chick otoconia did not exhibit the multifaceted surface morphology seen in embryonic rat otoconia. Comparisons of the same fields of otoconia under phase contrast microscopy and polarized light microscopy indicated that the freshly dissected otoconia of embryos exhibit little or no unmineralized (non-birefringent) material but that glutaraldehyde-fixed otoconia exhibited unmineralized areas where etching had occurred. Size frequency distributions of freshly dissected embryonic and mature otoconia in five ages of embryos and hatched chicks were consistent with a hypothesized developmental sequence of otoconia.

Animals↗
PubMed1984

Centrifugation of 2 g does not affect otoconial mineralization in chick embryos.

Chick embryos were grown on a rotating centrifuge for periods of 2 wk to study the effects of increased gravity on the relative growth of their otoliths and femurs. Embryos, 20-21 days of age, centrifuged at 2 g showed no difference in utricular otoconial CaCO3 weights and femur CaPO4 weights compared with stationary control embryos of the same age. In addition, control embryos rotated at the center of the centrifuge had otoconial CaCO3 weights and femur CaPO4 weights not significantly different from stationary controls or from embryos rotated at 2 g. Accordingly these data do not support the hypothesis that the weight of the embryonic otoconial membrane is involved in the feedback regulation of its growth.

Animals↗