Ultrastructural changes of the hypothalamo-hypophysial neurosecretory system in the magnesium deficient rats

A magnesium deficient diet caused transient but marked degenerative changes in the rat hypothalamo-hypophysial neurosecretory system which strongly resembled in many ultrastructural respects those induced by a prolonged administration of aldosterone as previously reported by us. The possible mechanism for this selective alteration in the neurosecretory neurons has been briefly discussed with regard to aldosterone secretion.

Scanning electron microscopy of epididymal ducts in the Japanese monkey (Macacus fuscatus) with special reference to the architectural analysis of stereocilia

The luminal surface of the initial segment of the epididymal duct in the Japanese monkey was observed under a field emission type scanning electron microscope. The long, slender stereocilia projecting from the apical surface of the columnar cells were found to be closely arranged in a funnel-like form opening to the lumen. The funnels formed by stereocilia were also confirmed by observation of thin sections cut from the same specimen used for scanning electron microscopy and their bottom was located in the center of the vertex of each columnar cell.

Chromosome mutations and pH disturbances

Chromosomal anomalies, namely hypodiploidies, hyperdiploidies, and endoreduplications, developed in nearly 25% of metaphase plates of replicating human lymphocytes exposed in vitro to either acid (6.5 to 6.9) or alkaline (8.4 to 8.8) pH equilibriums. The G group was most susceptible to aneuploid formation. Mammalian mutations may develop as the result of a pH disturbance during cleavage of the fertilized zygote.

In vitro culture of wheat. III. Anther culture of the a genome aneuploids in common wheat

Callus induction was examined using the anthers of Triticum aestivum cv. Chinese Spring and its aneuploids for the A genome chromosomes (ditelo-1A(L), -2A(S), -3A(α), -4A(α), -5A(L), -6A(α), -7A(S), nulli-1A, -2A, -4A and mono-4A) to determine the genetic role of individual chromosomes or chromosome arms in callus formation. An attempt was also made to establish the best culture conditions for callus formation from the anthers of the same wheat.Results showed that: (1) Callus was mostly induced from the anther filament. The frequency varied with the strain: ditelo-4A(α) showed the highest frequency (41.3 %), followed by nulli-4A (16.9%), in contrast to low frequencies for the normal strain and the other aneuploid strains. Undoubtedly, some genetic factor(s) for inhibiting callus induction is located on the β arm of chromosome 4A. (2) 2,4-D was needed to induce callus, but IAA and kinetin had no effect. 3 % sucrose was more favourable than 6 % for callus formation. Anthers cultured at the middle-uninucleate stage produced calluses more easily than those cultured at the other uninucleate stages (early or late). (3) A callus originating from the pollen of nulli-2A was obtained. From this, many albinotic plantlets were produced on a medium containing no 2,4-D.