Effects of Chronic Renal Failure (CRF) on the Sperm Nucleus Capacity
to Fertilize Oocytes
^{1,2}N. Sofikitis, ²T. Toda, ¹I. Miyagawa, ³P. M.
Zavos, ¹G. Mekras. ¹Dept of Urology, Tottori University
School of Medicine, Yonago, Japan; ²Dept of Urology, The New
York Hospital-Cornell University Medical Center, New York, NY; ³University
of Kentucky, Lexington, KY
Objective: The detrimental effect of CRF on male fertility potential
has been attributable to subnormal values of sperm concentration
and motility and to decreased libido. However, there is no information
whether CRF affects the sperm structures and specifically the nucleus
ability to undergo the proper alterations characterizing the last
events of the fertilization process. Our objective was to evaluate
the influence of CRF on the physiological transformations of sperm
nucleus within rabbit oocytes.
Design: Embryo development after ooplasmic injections of sperm nuclei
isolated from healthy vs CRF-animals was compared.
Materials and Methods: Right nephrectomy was performed in 5 male
mature rabbits (group A). Two weeks later a part of the left kidney
(approximately two-thirds of the tissue) was resected. An additional
group of same age male animals (n=5) underwent a two stage sham-operation
(group B). Two months after the second operation, urea, creatinine,
and testosterone were measured in the peripheral blood. Nuclei from
caudal epididymal spermatozoa were collected by sonication of spermatozoa
(one 10-seconds burst or one 40-seconds burst at 110 W power output)
and subsequent density gradient centrifugation. Twenty nuclei were
collected from each animal of both groups A and B. A single nucleus
was injected into one mechanically stimulated oocyte. Within each
group, 100 oocytes were injected. The injected oocytes were cultured
at 37°C for 24 hours in a medium similar to that described by
Carney and Foote (J Reprod Fertil 91:113) but it contained Dulbecco's
low glucose modified Eagle's medium mixed 1:1 with RPMI 1640 medium
(Gibco Co., Grand Island, NY). Oocytes were observed at various times
after microinjections. An oocyte was considered activated when two
polar bodies and a well-developed female pronucleus were observed.
Results: Creatinine and urea values were significantly higher in
group A than in group B (Wilcoxon's test; P <|0.05). In contrast,
testosterone values were significantly lower in group A (P<0.05).
There were no significant differences (P>0.05; Chi-square test)
in the % of activated oocytes between groups A and B (63 vs 61, respectively).
The ratio 100× cleaved oocytes/activated oocytes at the end
of the culture period was significantly larger (P <|0.05) in group
B (68) than in group A (20). The remaining non-cleaved activated
oocytes in both groups were arrested in pronuclear stage or during
the process of the first cleavage. Transformation of sperm nuclei
into well-developed pronuclei was observed in all of the activated
oocytes in both groups A and B.
Conclusions: Our results suggest that CRF does not influence the
sperm nucleus capacity to transform into male pronucleus. However,
oocytes fertilized by sperm nuclei isolated from CRF-animals have
a lower potential for cleavage.
Source: 1995 ASRM Meeting
