Application of frozen hydrated x-ray microanalysis to bulk frozen embryological tissue

Abstract

The examination of bulk frozen fully hydrated tissue by secondary electron and characteristic x-ray emission presents opportunities particularly suited to the study of rapidly differentiating embryological tissue. Because of the extended magnification range of the scanning electron microscope (SEM), embryonic development can be followed from the macroscopic egg to the microscopic adult cells, maintaining familiar visual clues. Advantages such as ease of handling, preservation of morphological relationships, increased heat dissipation and reduced contamination have been discussed previously in the literature and apply to frozen hydrated tissue in general. X-ray microanalysis of fully frozen hydrated embryos may be viewed as an extention of classical dissection techniques which allows selectivity without separation. Phenomena occurring within the unicellular egg such as fertilization, polarization and yolk granule composition can be examined by x-ray microanalysis without prior physical or chemical manipulation. Chemical gradients can be detected in the unperturbed, frozen hydrated matrix.