Sperm Head Morphology Research Articles

Cryopreservation of Atlantic cod Gadus morhua L. spermatozoa: Effects of extender composition and freezing rate on sperm motility, velocity and morphology

Broodstock selection programs are currently underway for Atlantic cod ( Gadus morhua). To complement and further these selection programs we need to develop sperm cryopreservation procedures. This will allow genomic DNA from males from selected individuals or stocks to be frozen and conserved in perpetuity. In our study we used a full factorial ANOVA design to examine the effects of diluent (Mounib’s sucrose-based diluent, Hanks’ Balanced Salt Solution, Mounib’s sucrose-based diluent + hen’s egg yolk, and Hanks’ Balanced Salt Solution + hen’s egg yolk), cryoprotectant (propylene glycol, dimethyl sulphoxide, and glycerol), and freezing rate (−2.5, −5.0, −7.5, and −10.0 °C/min) on motility of cod frozen–thawed sperm. Sperm velocity and morphometric analyses of sperm heads and flagella were also assessed. We found that sperm motility-recovery index was strongly influenced by the presence of higher-order interactions of the factors we tested. The best cryoprotection used diluents that contained hen’s egg yolk. Generally, extenders containing propylene glycol yielded higher post-thaw sperm motilities than those with dimethyl sulphoxide or glycerol. In comparison to sperm from other frozen–thawed extenders, sperm from extenders supplemented with propylene glycol had significantly higher curvilinear velocity. Cryopreservation showed no impact on sperm head morphology parameters, however, considerable damage to frozen-thawed sperm flagella was observed. We believe that our experimental/statistical approach and our results add significantly new information to the study of semen biology/cryobiology in fishes. Our findings are also highly relevant to the development of cod mariculture and for aiding in conservation efforts of this very important marine species.

Inherited sperm head abnormalities in the B10.M mouse strain

Examination of sperm head morphology is one of the requisite tests of the functional capacity of semen in reproduction. In the present study, genetic effects on morphological sperm head abnormalities in mice were investigated. The frequency of abnormal spermatozoa was determined in 17 inbred mouse strains and it was found that strain B10.M had the highest frequency of abnormal spermatozoa (44.7%). Segregation analysis was then used to show that the abnormal sperm phenotype in B10.M mice was inherited. The results indicated that this sperm abnormality was controlled by two distinct recessive alleles. It is proposed that the high frequency of the heritable abnormal sperm phenotype in the mouse B10.M strain explains the subfertility of this strain, as evidenced by its reduced litter size.

Oocyte activation ability correlates with head flatness and presence of perinuclear theca substance in human and mouse sperm

Recent studies indicate that round-headed sperm cannot activate oocytes and lack the postacrosomal sheath (PAS) or perinuclear theca (PT), although normal flat-headed sperm can activate oocytes and do have PAS (PT). In this study, we investigated how oocyte activation ability correlates with sperm head morphology (round and flat) and the presence of PT, by studying MN13, a representative molecule of the PT. We analyzed sperm with flat and round heads from infertile patients with globozoospermia (n = 1) and teratozoospermia (n = 1), and also from GOPC(-/-) mice, an animal model of human globozoospermia. Differential interference contrast image analysis, immunocytochemistry with MN13 antibody, transmission electron microscopy and an oocyte activation assay (assessing pronucleus formation) with ICSI were used. Flat-headed (control) sperm from both a healthy fertile volunteer man and wild-type mice had MN13 and PAS (PT). Flat-headed sperm (<5% of the population) from GOPC(-/-) mice also had both MN13 and PAS (PT), and they showed high oocyte activation ability. In contrast, round-headed sperm from a globozoospermia patient (100%) and GOPC(-/-) mice (>95% of the population) had neither MN13, nor PAS (PT), nor oocyte activation ability. Oocyte activation was higher in flat- versus round-headed sperm from GOPC(-/-) mice (P < 0.05). Oocyte activation ability may be related to sperm head flatness and presence of MN13 and PAS (PT) in human and mouse sperm. This information is a first step towards the possibility of selecting good-quality sperm with high oocyte activation ability for ICSI.

Increased Seminal Plasma Lead Levels Adversely Affect Semen Function in Painters Exposed to Lead Containing Paints.

Lead, a major contaminant around the world, is highly used in paint manufacturing due to its high anticorrosive properties. Recent reports had clearly indicated high lead content among India paints used for commercial purposes. Painters are continuously exposed to these high lead containing paints during painting of both commercial as well as house hold buildings. Lead is well known to reduce fertility in both animals as well as in humans also; we therefore aimed to measure blood lead level and its possible effect on semen functions in painters. Blood lead (BPb), activity of delta-aminolevulinc acid dehydratase (ALAD), seminal lead (SPb), parameters of semen quality, activities of antioxidants enzyme and reproductive endocrine functions in seminal plasma were measured in 103 healthy male workers, 20-40 years of age. The group contained 53 painters with slide to moderate occupational exposure to lead and 50 references subjects. All of the subjects lived in Lucknow, India. Significant (P<0.05) correlations of blood lead, delta-aminolevulinc acid dehydratase and seminal fluid lead with reproductive parameters indicated a lead related decreased in sperm density, mainly in counts of motile and viable sperm, in the percentage and count of progressively motile sperm, in antioxidant status of seminal plasma i.e. super oxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH) and total antioxidant capacity of seminal plasma (TAC) where as simultaneously we also observed significant increase in abnormal sperm head and tail morphology, ROS, lipid peroxidation products (TBARS) and serum testosterone. Moreover, these associations were further confirmed by the results of multiple regression, which also showed significant (P<0.05) influence of blood lead with decreased sperm motility, antioxidant enzyme activity, TAC and increased ROS, serum testosterone. However no significant blood lead related influence was found on semen volume and liquefaction time. The seminal concentration of lead had a highly significant (P<0.01) correlation with blood lead levels (r=0.621). The overall study results indicate that even low exposure to lead (BPb<400 μg/L) can significantly reduced human semen quality with showing conclusive evidence of impairment of male reproductive endocrine functions. The use of lead in paints in India is completely unregulated and routine surveillance of paints for lead content is still lacking therefore serious consideration should be given to the urgent inclusion of regulations and bans on the use of lead in paints. (poster)

Raman spectroscopy of DNA packaging in individual human sperm cells distinguishes normal from abnormal cells

Healthy human males produce sperm cells of which about 25-40% have abnormal head shapes. Increases in the percentage of sperm exhibiting aberrant sperm head morphologies have been correlated with male infertility, and biochemical studies of pooled sperm have suggested that sperm with abnormal shape may contain DNA that has not been properly repackaged by protamine during spermatid development. We have used micro-Raman spectroscopy to obtain Raman spectra from individual human sperm cells and examined how differences in the Raman spectra of sperm chromatin correlate with cell shape. We show that Raman spectra of individual sperm cells contain vibrational marker modes that can be used to assess the efficiency of DNA-packaging for each cell. Raman spectra obtained from sperm cells with normal shape provide evidence that DNA in these sperm is very efficiently packaged. We find, however, that the relative protein content per cell and DNA packaging efficiencies are distributed over a relatively wide range for sperm cells with both normal and abnormal shape. These findings indicate that single cell Raman spectroscopy should be a valuable tool in assessing the quality of sperm cells for in-vitro fertilization.

On the morphology of spermatozoa in some African murines (Rodentia, Muridae): the taxonomic and phylogenetic aspects

A comparative analysis of sperm-head morphology and measurements in 17 species from nine genera of African Murinae: Rattus rattus, Mastomys coucha, M. huberti, M. erythroleucus, Mastomys sp. 2, Praomys albipes, P. fumatus, Mus mahomet, Arvicanthis somalicus, A. abyssinicus, A. dembeensis, Arvicanthis sp., Lemniscomys macculus, Pelomys harringtoni, Acomys cahirinus, Acomys sp., Uranomys ruddi, was carried out. Spermatozoa of all examined species are of the same basic type. They consist of an asymmetrical head, falciform or scythelike in shape, and a tail attached to the ventrocaudal surface of the head. There are great interspecific differences in sperm morphology and size. The significance of this variation for estimation of taxonomic aspects and phylogenetic relationships among the species, as well as between them and other groups, is discussed. The sperm morphology supports a close evolutionary relationship among the genera Lemniscomys and Arvicanthis. It also indicates that Pelomys is distinctive. The relationships between Acomys and Uranomys are discussed.

Chromatin cytophotometric analysis of abnormal bovine spermatozoa.

Sperm head morphology is basically conditioned by the nuclear structure. The aim of the present work was to study the relation between nuclear morphological features, DNA content and chromatin distribution in morphologically normal vs. abnormal bovine spermatozoa. To this end, individual Feulgen-reacted spermatozoa were cytophotometrically studied. Chromatin compactation was evaluated by means of nuclear area, as well as mean and maximal absorbance of each nucleus. Morphological abnormality analysed included large, small, pear, narrow and round shapes, together with presumably 'diploid' sperms. Both large and small spermatozoa have a DNA content that does not differ significantly from normal values, but their area and mean and maximal absorbance are significantly different. Size variation seems basically due to altered chromatin compactation. The pear shapes have a narrower neck and a significant increase in maximal absorbance alone, which is invariably recorded in the neck zone whose increase would indicate a change in distribution and/or compactation. The narrow and round shapes fail to present significant variations in studied parameters. The possible 'diploids' differ significantly from normal cells in all studied variables, with a little area increase.

231 SPERM SUBPOPULATIONS IN THE KOALA (PHASCOLARCTOS CINEREUS) EJACULATE

Koala semen contains a heterogeneous mixture of sperm morphotypes, mainly attributable to extreme degree of shape variability displayed by the hooked sperm head. By analogy with other species, we anticipate that the morphotypes may exhibit correspondingly different sperm-motility behaviors, largely caused by the differences in hydrodynamic interactions with the suspending media. This trend has been shown in human spermatozoa where motility behavior was demonstrably correlated with the sperm head morphology (Overstreet et al. 1981). In this study, we have investigated the heterogeneity of koala sperm motility profiles in semen in an effort to determine whether distinct sperm subpopulations within ejaculates are recognizable by the use of computer-assisted sperm motility analysis. Ejaculates from 5 males were collected by electroejaculation, then diluted and transported in Tris-citrate-glucose (TCG) diluent. Spermatozoa were washed through a 35–60% Percoll gradient to separate seminal plasma and the majority of the prostatic bodies from spermatozoa. Spermatozoa from the washed pellet were then diluted in TCG at 35°C, incubated for 10 min, and video recorded using a negative phase ×10 objective. Sperm motion parameters were then analyzed using the Hobson sperm tracker (Hobson Vision Systems, UK: Holt et al. 1996 J. Androl. 17, 587–596). Multivariate pattern analysis (PATN; CSIRO Australia; Abaigar 1999 Biol. Reprod. 60, 32–41) was used to distinguish 3 sperm subgroups, consistently shown in each ejaculate, within the data (1936 tracks × 6 kinetic parameters; VCL, VAP, MAD, BCF, ALH, LIN). After group allocation by PATN, all parameters showed significant differences between each of the groups (P &lt; 0.0001). Group 1, approximately 25% of the sperm tracks, showed profiles of spermatozoa with fast, non-linear motility (VCL 106.88 ± 28.15; BCF 3.23 ± 3.81; LIN 14.08 ± 10.20). Group 2, approximately 27% of sperm tracks, showed profiles of fast, linear motility (VCL 63.92 ± 13.50; BCF 7.90 ± 3.42; LIN 28.10 ± 12.15). Group 3, 48% of sperm tracks, showed profiles of slow, non-linear or circular patterns of motility (VCL 39.05 ± 11.92; BCF 0.02 ± 0.35; LIN 5.15 ± 4.88). The recognition of 3 clearly identifiable subgroups supports our hypothesis that heterogeneity of sperm motility patterns exists within koala ejaculates. These may be a reflection of the heterogeneity in sperm-head morphotypes in koala semen, but that remains to be investigated in more detail. The clear distinctions between these groups, and the observation that all 3 subpopulations exist in each of the ejaculates, also suggest that the spermatozoa exhibit functional differences, possibly related to biochemical or maturational status. Many thanks to Dr. Michael Pyne and Dr. Vere Nicholson and their teams and animals at Currumbin Wildlife Sanctutary and Dreamwolrd QLD for all their help and support for the collection of samples.

Methotrexate-induced cytotoxicity and genotoxicity in germ cells of mice: Intervention of folic and folinic acid

Methotrexate (MTX) is an anti-metabolite widely used in the treatment of neoplastic disorders, rheumatoid arthritis and psoriasis. The basis for its therapeutic efficacy is the inhibition of dihydrofolate reductase (DHFR), a key enzyme in the folic acid (FA) metabolism. FA is a water-soluble vitamin which is involved in the synthesis of purines and pyrimidines, the essential precursors of DNA. Folinic acid (FNA) is the reduced form of FA that circumvents the inhibition of DHFR. Folate supplementation during MTX therapy for psoriasis and inflammatory arthritis reduces both toxicity and side effects without compromising the efficacy. Further, FNA supplementation reduces the common side effects of MTX in the treatment of juvenile idiopathic arthritis. FA and FNA are reported to have protective effects on MTX-induced genotoxicity in the somatic cells; however their protective effects on the germ cells have not been much explored. Previously, we evaluated the cytotoxic and genotoxic effects of MTX in the germ cells of mice. In the present study, we have intervened FA and FNA for the protection of germ cell toxicity induced by MTX in male swiss mice. The animals were pre-treated with FA at the doses of 50, 100 and 200 μg/kg for 4 consecutive days per week and on day five; MTX was administered at the dose of 20 mg/kg once. FNA was administered at the doses of 2.5, 5 and 10 mg/kg, 6 h (h) after single administration of MTX at the dose of 20 mg/kg. The dosing regimen was continued up to 10 weeks. The germ cell toxicity was evaluated using testes weight (wt), sperm count, sperm head morphology, sperm comet assay, histology, TUNEL and halo assay in testis. The results clearly demonstrate that prior administration of FA and post-treatment with FNA reduces the germ cell toxicity induced by MTX as evident from the decreased sperm head abnormalities, seminiferous tubule damage, sperm DNA damage, TUNEL positive cells and increased sperm counts. In the present study, we report that FA and FNA ameliorate the germ cell toxicity of MTX in mice.

Sperm morphology and its influence on swimming speed in Atlantic cod

Summary A protocol for staining fish spermatozoa using Hemacolor-stain was developed for light microscopy and successfully applied to Atlantic cod (Gadus morhua). Sperm head morphology was characterized by size (length, width, area and perimeter) and shape (ellipticity, rugosity, elongation and regularity) (n = 6500 spermatozoa), and tail length (n = 260 spermatozoa) of 12 individual cod. Two spermatozoa heads sperm were clearly identified: round and elongated, being this last one more abundant (86.3%). No evidence was detected in tail length for both head types. Tails were 96.4% length of sperm and no difference in tail length was detected between head types. A positive correlation existed between head and tail length, with variability existing among males. Sperm swimming speeds varied among males with a maximum curvilinear velocity between 151.5 and 201.5 μm s−1. Mean swimming speed declined by 8.2% from 30 to 70 s post-activation. Spermatocrit was negatively correlated with curvilinear velocity at 30 s post-activation. Males with short sperm heads maintained their swimming velocity for longer periods that those with long heads. Fulton’s condition factor was negatively correlated with straightness of path.

Cytotoxic and genotoxic effects of methotrexate in germ cells of male Swiss mice

Methotrexate (MTX) is an anti-metabolite drug widely used in the treatment of neoplastic disorders, rheumatoid arthritis and psoriasis. Developed as an analogue of folic acid, it inhibits purine and pyrimidine synthesis that accounts for its therapeutic efficacy as well as for its toxicities. MTX has narrow therapeutic index and its toxicity has been reported in various organ systems including gastrointestinal, haematologic and central nervous system. The objective of the present study is to investigate the germ cell toxicity induced by MTX in male Swiss mice. MTX was administered intraperitoneally (ip) at the doses of 5, 10, 20 and 40 mg/kg to mice (20–25 g) weekly once (wk) for 5 and 10 weeks. The animals were sacrificed 1 week after receiving the last treatment of MTX. The germ cell toxicity was evaluated using testes weight (wt), sperm count, sperm head morphology, sperm comet assay, histology, TUNEL and halo assay in testis. MTX treatment significantly reduced the sperm count and increased the occurrence of sperm head abnormalities in a dose dependent manner. It induced the testicular toxicity as evident from the histology of testis. Sperm comet, TUNEL and halo assay in testis also revealed significant DNA damage after MTX treatment. On the basis of the present study, it can be concluded that MTX induced germ cell toxicity in mice.

Sperm head morphology is related to high deoxyribonucleic acid stainability assessed by sperm chromatin structure assay

To examine the relationship between sperm strict morphology and sperm chromatin integrity. Prospective study. Infertility clinic. Eighty-seven consecutive semen samples from non-azoospermic men presenting for infertility evaluation and 6 samples from fertile donors. Assessment of standard semen parameters and sperm chromatin structure assay (SCSA) parameters (%DFI [DNA fragmentation index] and %HDS [high DNA stainability]). Evaluation of %HDS and %DFI after treatment with dithiothreitol (a thiol-reducing agent used to decondense sperm nuclei) was also undertaken. Relationship between sperm strict morphology defects and SCSA parameters (%DFI and %HDS). We observed significant relationships between the percentage of normal sperm forms and both %HDS (r = -0.40) and sperm motility (r = 0.32). We also found significant relationships between sperm head defects and both %HDS (r = 0.40) and sperm concentration (r = -0.39). Sperm tail, midpiece, and neck defects were not significantly related to the SCSA parameters. Treatment of spermatozoa with dithiothreitol (to induce decondensation) resulted in a substantial increase in %HDS but no measurable change in %DFI. The observed relationship between sperm head defects and %HDS suggests that sperm head abnormalities may, in part, be due to incomplete sperm chromatin condensation.

A Common Protamine 1 Promoter Polymorphism (-190 C-&gt;A) Correlates With Abnormal Sperm Morphology and Increased Protamine P1/P2 Ratio in Infertile Patients

It is known that targeting the protamine 1 gene in mice leads to infertility, abnormal chromatin packaging, and abnormal sperm morphology. Because many infertile patients also have an abnormal sperm morphology and chromatin packaging, the human protamine 1 gene (PRM1) is an important candidate to screen for potential mutations. In this work, we have screened the PRM1 gene in search of potential mutations and determined the sperm morphology and the ratio between protamine 1 and protamine 2 (P1/P2 ratio). Direct sequencing of the PRM1 promoter led to the identification of a common single-nucleotide polymorphism (SNP; -190 C-->A). The -190 AA genotype was detected at a higher frequency (13.8%) in patients with markedly altered sperm morphology (<or=9% normal forms) compared with other patients (4.5%; P < .05) or compared with controls (2.97%; P < .005). The allelic frequency of the PRM1 -190 C-->A change was also consistently higher (.331) in infertile patients with a markedly altered morphology compared with population controls (.178; P < .01). Additionally, we have determined that the P1/P2 ratio is significantly increased in patients with the PRM1 -190 AA genotype compared with patients with the CA or CC genotypes (P = .006, Mann-Whitney). These findings indicate that the common PRM1 -190 C-->A polymorphism identified is associated with abnormal sperm head morphology and abnormal P1/P2 ratio in infertile patients.

Astaxanthin inhibits cytotoxic and genotoxic effects of cyclophosphamide in mice germ cells

Cyclophosphamide (CP), an alkylating agent used in the treatment of several cancers as well as an immunosuppressant in rheumatoid arthritis. It is used against several cancers due to its broad spectrum efficacy, but at the same time possesses unwanted risks for occupational exposure as well as therapy related toxicities to patients. The present study was aimed to investigate the protective effect of astaxanthin (AST) a red carotenoid pigment on CP induced germ cell toxicity in male mice. CP was administered intraperitoneally (i.p.) at the dose of 50, 100 and 200 mg/kg body weight to mice (20–25 g) once in a week for a period of five weeks. AST was given at the dose of 25 mg/kg per oral (p.o.) for five consecutive days in a week for five weeks. The animals were sacrificed one week after the last injection of CP. The protective effect of AST against CP induced male germ cell toxicity was evaluated using body weight, testes and epididymis weight, sperm count, sperm head morphology, sperm comet assay, histology of testes and TUNEL assay. AST treatment significantly improved the testes weight, sperm count and sperm head morphology as compared to only CP treated animals. The result of comet assay showed that AST treatment significantly restored the sperm DNA damage induced by CP. Further, AST treatment showed protection against CP induced testicular toxicity as evident from testes histology and TUNEL assay. The present results indicate the chemoprotective potential of AST against CP induced germ cell toxicity in mice.

Seasonal Variation in Nuclear DNA Integrity of Frozen–Thawed Spermatozoa from Thai AI Swamp Buffaloes (Bubalus bubalis)

In this study, we investigated the susceptibility of frozen-thawed swamp buffalo sperm nuclear DNA to undergo controlled acid-induced denaturation in situ, as analysed by flow cytometry, and aimed to correlate the results with sperm head morphology over three seasons in tropical Thailand. Artificial insemination (AI) doses (n = 218) from 18 AI buffalo sires, prepared between 1980 and 1989 and 2003 and 2005, were tested and compared among three seasons, the rainy season, July-October; winter, November-February; and summer, March-June. The overall mean of DNA fragmentation index (DFI) (+/- SD) was 1.84 +/- 1.68%, range from 0.19 to 7.92%, with 0.221 +/- 0.021 of the x-DFI ranging from 0.190 to 0.350 and 0.023 +/- 0.009 of the SD-DFI ranging from 0.010 to 0.070. The DFI was consistently low (range 1.40 +/- 0.21% to 2.16 +/- 0.21%; LSM +/- SEM), with x-DFI ranging from 0.216 +/- 0.003 to 0.225 +/- 0.003 and SD-DFI ranging from 0.022 +/- 0.001 to 0.024 +/- 0.001 across the seasons. The DFI was low enough to be related to high fertility potential. However, DFI values varied statistically among seasons, being lower in the rainy season (1.40 +/- 0.21%, P < 0.05) than in winter (2.16 +/- 0.21%) or summer (2.00 +/- 0.20%), and were also affected by the year of semen collection and processing (P < 0.001). The proportion of morphologically abnormal sperm head shapes was low, with no significant differences between seasons. However, DFI was significantly related to the proportion of loose abnormal sperm heads (r = 0.27, P < 0.01). In conclusion, frozen-thawed swamp buffalo sperm chromatin integrity is not seriously damaged by cryopreservation or affected by the seasonal variations in temperature and humidity seen in tropical Thailand.

Identification of sperm morphometric subpopulations in the canine ejaculate: do they reflect different subpopulations in sperm chromatin integrity?

A statistical approach using sequentially principal component analysis (PCA) clustering and discriminant analysis was developed to disclose morphometric sperm subpopulations. In addition, we used a similar approach to disclose subpopulations of spermatozoa with different degrees of DNA fragmentation. It is widely accepted that sperm morphology is a strong indicator of semen quality and since the sperm head mainly comprises the sperm DNA, it has been proposed that subtle changes in sperm head morphology may be related to abnormal DNA content. Semen from four mongrel dogs (five replicates per dog) were used to investigate DNA quality by means of the sperm chromatin structure assay (SCSA), and for computerized sperm morphometry (ASMA). Each sperm head was measured for nine primary parameters: head area (A), head perimeter (P), head length (L), head width (W), acrosome area (%), midpiece width (w), midpiece area (a), distance (d) between the major axes of the head and midpiece, angle (theta) of divergence of the midpiece from the head axis; and four parameters of head shape: FUN1 (L/W), FUN2 (4pi A/P2), FUN3 ((L - W)/(L + W)) and FUN 4 (pi LW/4A). The data matrix consisted of 2361 observations, (morphometric analysis on individual spermatozoa) and 63,815 observations for the DNA integrity. The PCA analysis revealed five variables with Eigen values over 1, representing more than 79% of the cumulative variance. The morphometric data revealed five sperm subpopulations, while the DNA data gave six subpopulations of spermatozoa with different DNA integrity. Significant differences were found in the percentage of spermatozoa falling in each cluster among dogs (p < 0.05). Linear regression models including sperm head shape factors 2, 3 and 4 predicted the amount of denatured DNA within each individual spermatozoon (p < 0.001). We conclude that the ASMA analysis can be considered a powerful tool to improve the spermiogram.

Interspecific variation of sperm morphology in the Australian rodent genus Zyzomys

AbstractThe sperm head morphology and tail length of two species of Australian rock rats, Zyzomys argurus and Zyzomys pedunculatus, are presented. In Z. argurus the sperm head has an apical hook together with two ventral processes extending from the upper concave surface that are largely composed of cytoskeletal material, and the sperm tail is about 135 µm in length. By contrast, in Z. pedunculatus the sperm head is paddle‐shaped with the nucleus capped by an acrosome that has a large apical segment and is surrounded by a thin layer of cytoskeletal material, and the sperm tail is only around 85 µm in length. Since the structure of the spermatozoon of Z. argurus is similar to that of most of the old endemic Australian rodents it is presumed to be the ancestral condition within the Zyzomys genus with that of Z. pedunculatus being highly derived and showing convergence with the sperm structure in some other orders of mammals.

An in vivo Evaluation of the Induction of Abnormal Sperm Morphology by Sulphamethoxypyridazine: Pyrimethamine (Metakelfin®)

The effects of sulphamethoxypyridazine: Pyrimethamine (Metakelfin) a combination antimalarial drug on mouse sperm head morphology were evaluated in University of Ibadan Veterinary F1 mice. Five different dose levels of 3.85:0.19; 7.7:0.38; 15.4:0.76; 23.1:1.13 and 30.8:1.54 mg kg(-1) body weight of sulphamethoxypridazine:pyrimetamine, respectively were administered to the animals by a schedule of 5 consecutive daily intraperitoneal (i.p.) injections. The sperm of the mice from the cauda epididymis were examined 5 weeks after treatment. Metakelfin induced sperm head abnormalities; however, of the 5 doses sampled; only the 7.7:0.38 mg kg(-1) dose, corresponding to 0.5x the human therapeutic dose (HTD0), gave a statistically significant (p > 0.05) increase over the negative control value of 2.53% abnormality. All the other dose level treatments did not yield statistically significant increase over the negative control value. The 15.4:0.77 mg kg(-1) dose showed 3.5% abnormality and fewer abnormalities than the preceding lower dose. The drug is probably not mutagenic as induction of sperm head abnormality was not dose dependent.

An in vivo Evaluation of Induction of Abnormal Sperm Morphology by Ivermectin MSD (Mectizan®)

The in vivo effects of orally administered ivermectin (Mectizan) on sperm head morphology of albino mice were evaluated. Four different dose levels of 0.25, 0.5, 1.0 and 1.5 x the human therapeutic dose of 150 g kg(-1) body weight, were administered to the animals. The animals were exposed to a single oral treatment. The sperm of the mice from the cauda epididymes were examined 5 and 7 weeks after treatment. Ivermectin (Mectizan) induced sperm head abnormalities; however, the induction was not significantly elevated above the negative control value. Furthermore, the induction of the sperm head abnormalities was not strictly dose-dependent and there was also no correlation between dose level of administered drug and incidence of abnormal sperms. This indicates that the drug might not be mutagenic.

P-990: The Golden Ratio and an aesthetically pleasing sperm: Towards an objective assessment of sperm head morphology

Sperm morphology is a subjective assessment that has been linked with fertility potential. According to the published acceptable measurements, the sperm head should have the following dimensions: length: 4.0-4.5 microns; width: 2.5-3.5 microns (WHO, 1999) with a length-to-width ratio of 1.50 to 1.75. Interestingly, this ratio is consistent with what is commonly found throughout nature and is defined as the Golden Ratio (phi=1.618). Objects (e.g. the Nautilus) with this Golden Ratio are aesthetically pleasing to the eye.