Date of Award
Doctor of Philosophy (PhD)
R. James Swanson
Determining potential maternal or paternal sources of abnormal chromosomal constitution gives opportunity for preconception genetic counseling. The most direct determination is achieved by analyzing the nuclear constitution of the gametes.
The present study evaluated the integrity of human spermatozoal nuclear material in the two condensation stages of chromatin and chromosomes. Original semen samples (ORI) and their swim-up fractions (SW, selected for motility) from men of known (donors) and unknown (patients) fertility were analyzed. The extent of chromatin condensation was assessed by light microscopy and flow cytometry during the time course of a chemically-induced decondensation reaction.
Motile spermatozoa were used to inseminate hamster oocytes for human sperm chromosomal analysis (original method). A modification of this technique was introduced in an attempt to overcome the motility barrier required for fertilization. Spermatozoa rendered immotile by cryodamage were directly microinjected into the perivitelline space of hamster oocytes in order to obtain fertilization and possible chromosomal development.
The swim-up-selected spermatozoa showed a higher resistance to the chromatin decondensation assay (10.53% decondensed) than their corresponding nonselected whole semen samples (94.74%). Sperm chromosomal analysis by the traditional technique was restricted to donor samples (86.7% fertilization rate) since all the patients failed to achieve fertilization. Although a high number of chromosomal complements were obtained (2362) only 7.4% provided complete information (range 0-56 complements/donor). The observed X/Y relationship (39/44) was not significantly different than the expected 1/1 ratio. Ten spermatozoa (7.69%) carried structural and 3.08% carried numerical abnormalities. High rates of fertilization (64-86%) with low rates of polyspermy ($
Swim-up selected spermatozoa have a higher resistance to the in-vitro induced nuclear chromatin decondensation assay (NCDA) than their corresponding ORI samples, which may correlate with their greater nuclear stability. Although SW procedures are invaluable as an aid in infertility treatment due to their selectivity in motility, morphology, fertilizing ability, chromatin resistance, etc. they are not able to discriminate against spermatozoal carriers of genetic defects.
Bocca, Silvina M..
"Analysis of Human Sperm Chromatin Integrity"
(1994). Doctor of Philosophy (PhD), dissertation, Biological Sciences, Old Dominion University, DOI: 10.25777/3bga-3p69