Light and electron microscopic analysis of human testicular spermatozoa and spermatids from frozen and thawed testicular biopsies

The morphological changes caused by freezing and thawing human testicular s permatozoa have been assessed here. Retrieval of testicular biopsies was ca rried out on six patients with obstructive azoospermia preparatory to intra cytoplasmic sperm injection (ICSI). Light microscope analysis was carried o ut on testicular cells and ultrastructural analysis was carried out on sper matozoa and different spermatid stages before and after the freezing proced ure. Upon examination under light microscopy, all germ cells presented incr eased vacuolization in their cytoplasm and shrinkage or swelling of the nuc lei and cytoplasmic membranes. These altered structures were accentuated in the spermatocyte I cell which often presented disrupted membranes. The ult rastructural findings under transmission electron microscopy demonstrated t hat after freezing and thawing the major types of cryoinjury were the swell ing and rupture of inner and outer acrosomal and plasma membranes. The acro some material often appeared as dispersed material or as condensed spots or was even lost. Such damage was observed mainly at the spermatozoa and late spermatid stages. We conclude that the freezing and thawing of testicular biopsies causes similar morphological damage to testicular spermatozoa and frozen-thawed ejaculated spermatozoa. It is still unclear whether these cha nges in testicular spermatozoa after freezing and thawing may compromise it s use in the ICSI procedure.