[Early embryo orientation by direction of the cardinal point in natural clutches of two ranidae species inhabiting geographically distant regions]. / Orientatsiia rannikh zarodyshei po napravleniiam stran sveta v estestvennykh kladkakh dvukh vidov ranidae, obitaiushchikh v geograficheski otdalennykh regionakh.

The azimuth (the least angle with the north-south direction) of the first cleavage furrow and anteroposterior axes of neurula was measured on projections of photographs of natural clutches. The azimuth distribution of the craniocaudal axis of Rana dalmatina neurulae in clutches from southern Italy and the first cleavage furrows of R. arvalis embryos in clutches from central Russia proved identical. Both craniocaudal axes and first cleavage furrows were mostly oriented from west to east. The azimuth distribution of the craniocaudal axis of R. arvalis neurulae in clutches subjected to repeated cold shock proved to be random. The causes and mechanisms of predominant orientation of the embryos in natural clutches of frogs are discussed. We propose that magnetic sensitivity is acquired by cytoskeleton elements, most likely microtubules, during reorganization in the course of normal development or due to experimental influences.

[Echographic profile of senile disciform macular degeneration and problems of differential diagnosis]. / Profilo ecografico della degenerazione disciforme senile della macula e problemi di diagnosi differenziale.

Authors describe the echographic characteristics A and B-scan of the disciform macular degeneration. They also examine the problems of an echographic differential diagnosis between the upper described pathological pattern and the melanoma of small dimensions growing from the posterior pole. With the B-scan, both pathological patterns show a zone of echoes which is of solid aspect, not so much raised from the retina. The only characteristic element is the choroideal excavation that we always have in the choroideal melanoma and never in the disciform macular degeneration. Even the A-scan is useful mostly if we reduce the amplification level we have a separation of the internal echoes better in the disciform macular degeneration than in the melanoma. Moreover in some cases when the pathological area is small, we cannot have an echographic differential diagnosis in order to recognize the lesion.