The effects of different preparative procedures on the ultrastructure of the hamster ovary. I. Effects of various fixative solutions on ovarian oocytes and their granulosa cells.

Abstract

For fixation of ovarian oocytes and granulosa cells the percentage concentration of glutaraldehyde in the fixative solution makes little difference between 2 and 4 per cent as long as the osmolarity of the buffer falls between 195–225 milliosmoles. With 1 per cent glutaraldehyde, fixation is erratic. Buffer osmolarities of 95–115 mOsm result in swelling and leaching of cytoplasm regardless of glutaraldehyde concentration. Post-osmication reduces leaching but does not prevent swelling. Increase in osmolarity of the non-fixative portion of the solution to either isotonic or hypertonic levels with buffer ions, glucose or sucrose results in shrinkage which is reversed during post-osmication. Certain features remain constant regardless of fixative concentration or osmolarity: a) The presence among the pale granulosa cells in multilaminar follicles of small numbers of extremely dark cells, b) the irregular outlines of granulosa cell nuclei and of oocyte nuclei in follicles with two or more layers of granulosa cells, c) the typical features of atretic oocytes in multilaminar follicles. Mixtures of glutaraldehyde and osmium tetroxide do not preserve the cytoplasmic non-membranous lamellae characteristic of the hamster oocyte, and cause vesiculation of the endoplasmic reticulum. They appear to have no advantage for fixing ovarian tissue.