Effect of feeding guanidinoacetic acid and L‐arginine on the fertility rate and sperm penetration in the perivitelline layer of aged broiler breeder hens

Two experiments were conducted to evaluate the effects of feeding guanidinoacetic acid (GAA) and L‐arginine (ARG) on fertility and sperm penetration (SP) rate of broiler breeder hens. In the first experiment, a total of 200 broiler breeder hens (Ross 308) aged 53 week were randomly allotted to four dietary treatments (0, 0.6, 1.2 and 1.8 g GAA/kg diet) with five replicates of 10 birds each. In the second experiment, 320 broiler breeder hens (Ross 308) were used from 53 to 62 weeks of age in a 2 × 4 factorial arrangement (0 or 1.2 g GAA/kg diet along with 0, 3, 6 or 9 g ARG/kg diet). The hens received a diet containing 2800 kcal ME/kg and 14% CP. Sixteen sexually mature Ross 308 breeder roosters (34 weeks old) were used to artificially inseminate the hens. Fertility of the hens was determined in 61 and 62 weeks of age. The sperm penetration holes in the inner perivitelline layer (IPL) overlying the germinal disc were enumerated on days 3 and 7 following each insemination. Adding GAA to the breeder diet increased the number of SPs in the IPL and fertility in both experiments (p < 0.01). The interactive effect of ARG and GAA on the SP and fertility was significant. Supplementary ARG increased the SP rate in the IPL (p < 0.01). In conclusion, dietary supplementation of GAA and ARG might be potentially used to improve the fertility of broiler breeder hens at the later phase of the egg production period.     

In vitro formation of holes on the inner perivitelline layer of quail ovum by chicken spermatozoa

The aim of the present study was to examine whether chicken semen can be substituted for quail semen to conduct in vitro experiments on fertilization. Chicken spermatozoa was incubated with the inner perivitelline layer (IPL) isolated from the largest follicle in the quail ovary under in vitro conditions. The perforation of chicken and quail spermatozoa were assessed by counting the number of all visible holes in the pieces of IPL. No difference was found in the number of holes formed by the chicken sperm and quail IPL interaction compared with that between intraspecies. In addition, the number of holes in the IPL was significantly increased with the increase in sperm concentration from 1 × 10⁶ to 8 × 10⁶ sperm/mL (P < 0.05). Interestingly, after treatment of chicken spermatozoa with 2.5 mg/mL of the solubilized quail IPL followed by incubation with the intact chicken IPL, the number of holes in the intact chicken IPL was significantly decreased as compared with that of spermatozoa treated without the solubilized IPL (P < 0.05). This indicates that sperm receptors in the solubilized quail IPL and binding ligands on the chicken spermatozoa would find each other and bind, forming complexes and these complexes blocked the interaction between chicken spermatozoa and intact chicken IPL. These results show that: (i) chicken spermatozoa possess the penetrability into quail IPL; and (ii) a high degree of affinity via the receptor interactions exists between chicken spermatozoa and quail IPL. Therefore, it appears that the substitution of chicken semen for quail semen is possible to use as an in vitro technique to examine the sperm‐IPL interaction during fertilization in quail.     

Determination of the rate of true fertility in duck breeds by the combination of two in vitro methods

Embryonic mortality is a significant problem plaguing the hatching success. Its early forms are especially hardly distinguishable from true infertility. Propidium iodide (PI) staining of the germinal disc combined with outer perivitelline layer (OPVL) sperm counting was used for the determination of 'true' fertility of duck eggs in two different experiments: fertility investigation on fresh, unincubated eggs of Hungarian ducks and on incubated eggs of a crossbred, selected as 'infertile' at the 7th day of incubation. Examination of the relationship between OPVL sperm count and fertility seems to be an adequate tool for checking the effectiveness of insemination programmes and the fertilising capacity of poultry spermatozoa. The proportion of fertile eggs was around 50% when the number of OPVL sperm was between 0.1 and 0.2 spermatozoa/mm2. Ninety-nine percent of the eggs containing > 0.3 OPVL sperm/mm2 were fertile and all of the eggs containing < 0.05 sperm/mm2 were infertile. To assure the accuracy of fertility prediction by OPVL sperm counting, PI staining of the germinal disc was used to determine fertility in uncertain cases. Identification of very early embryonic mortality, i.e. that occurring before oviposition, is very difficult. The use of a dissecting microscope for the assessment of real fertility is suitable in most of the cases, while PI staining of the germinal discs proved to be more reliable for detecting very early embryonic death. The combination of the two methods proved to be a useful tool for detecting the 'true' fertility of duck eggs of different breeds.     

Assessing the efficiency of mating in broiler breeder flocks by enumerating the spermatozoa which penetrate the inner perivitelline layer over the germinal disc

1. The frequency distribution of points of hydrolysis produced by spermatozoa in the perivitelline layer from directly over the germinal disc was examined in 60 samples of 60 eggs from commercial broiler breeder flocks. 2. Typically, these distributions were positively skewed, although log transformation of the data revealed 2 populations: one representing eggs which contained no evidence of spermatozoa and another in which the data were, generally, normally distributed. 3. Problem flocks with low fertility had more eggs without evidence of spermatozoa and, compared to control flocks with acceptable fertility, a lower median and mean before and after log transformation, respectively. 4. In 4 flocks studied between 30 to 55 weeks of age, the median number of points-of-hydrolysis in samples of eggs fell from around 200 at peak to less that 20 at 55 weeks, whilst the mean proportion of fertile eggs laid by the whole flocks fell from 94% at peak to around 79% at 55 weeks. 5. A log-linear relationship was demonstrated between flock fertility and the median points-of-hydrolysis from the inner perivitelline layer over the germinal disc in samples of 60 eggs (R2=0.79). 6. The main advantages of this system for measuring sperm-in-eggs are that it is technically simple and presents a more expanded scale than fertility, so that an estimation of whole flock fertility can be derived from a sample of 60 eggs.     

Weekly monitoring of broiler breeder flock mating efficiency by sperm transfer into eggs

1. Sample fertility and the median number of points of hydrolysis produced by spermatozoa in the perivitelline layer from the germinal disc area were determined in samples of 60 eggs taken weekly from each of two commercial broiler breeder flocks. 2. Flock fertility remained above 90% from weeks 30 to 45, after which it fell in both flocks, reaching 85% in Flock A by week 51 and 76% in Flock B by week 55. 3. Sample fertility, as assessed by the Kosin test, followed a similar trend, but showed more variation; the same was true for the proportion of eggs with at least one perivitelline hole. 4. In Flock A, the median number of perivitelline holes in samples increased from 145 in week 30 to reach a maximum of 323 on week 39, thereafter falling to 109 in week 51; for Flock B, the equivalent figures for weeks 30, 36 and 55 were 160, 266 and 29, respectively. A quadratic model confirmed that the weekly sample median perivitelline holes peaked at weeks 40 and 37 in Flocks A and B, respectively. 5. The results show that transfer of spermatozoa by males into females and subsequently into eggs begins to decline 8 (Flock A) to 9 (Flock B) weeks before it is noticeable as a significant reduction in flock fertility and that mating efficiency, unlike fertility, is never in apparent equilibrium, but rises to a peak before 40 weeks and then falls. 6. The pattern of sperm transfer suggests that the reduction in fertility of broiler flocks could well be for social or for physiological reasons other than those associated with 'ageing'.     

Evaluation of semen from individual male domestic fowl by assessment of sperm perivitelline interaction in vitro and in vivo

1. Spermatozoa in semen samples from 8 individual male domestic fowls were shown to have a differential and characteristic ability to hydrolyse holes in the inner perivitelline layer from laid eggs in an in vitro assay. 2. The number of holes produced by samples of spermatozoa per unit area of inner perivitelline layer in vitro was linearly correlated with sperm ATP content ( r = 0.85) and motility (r=0.76). 3. The number of holes formed in the inner perivitelline layer in vitro was also linearly correlated with the numbers of holes formed in the inner perivitelline layer of eggs fertilised in vivo , in inseminated hens (r=0.90); and was correlated logarithmically with the proportion of fertile eggs laid by these hens.     

Effects of genotype and cryopreservation of avian semen on fertility and number of perivitelline spermatozoa

1. The fertility of freshly diluted and cryopreserved samples of semen obtained from a population of chickens selected for duration of fertility of cryopreserved spermatozoa (FS line) and its unselected control (FC line) were compared over a range of spermatozoa concentrations (10, 40, 80, and 160 × 10⁶ sperm/50 μ1 insemination).

2. The spermatozoa of the FS line had greater fertility than spermatozoa of the FC line, whether freshly diluted or cryopreserved. Cryopreservation resulted in a reduction in fertility, regardless of line. There were no significant line by genotype interactions.

3. There were fewer spermatozoa from the FG line than the FS line found in the perivitelline membrane (perivitelline spermatozoa). The increase in number of perivitelline spermatozoa with increasing sperm concentration was greater in the FS than FC line. However, the slope of the increase in sperm number in the perivitelline membrane with increasing concentrations of cryopreserved spermatozoa was zero.

4. A minimum of 10³ perivitelline spermatozoa must be found on day 2 post‐insemination for duration of fertility to exceed three days. The ability to produce spermatozoa capable of reaching the forming perivitelline membrane appears to be a quantitative, rather than a qualitative, trait and may be subject to genetic manipulation.     

In vitro assessment of semen for the prediction of fertility

The prediction of fertility is a primary goal in the field of reproductive medicine. The aim of the present paper is to describe the value of conventional and modern sperm analysis systems considering the process of fertilization. The classical assessment of motility and morphology enables the rough estimation of semen quality in order to select ejaculates for the use in artificial insemination. Recent methods for sperm diagnosis, such as fluorescent marking for the detection of sperm plasma membrane integrity, the hypoosmotic swelling test, and computer assisted semen analysis allow for the evaluation of a large number of spermatozoa and the assessment of sperm dynamics under in vitro-fertilization conditions. The oocyte penetration test investigates the ability of spermatozoa for capacitation, hyperactivation and acrosome reaction in vitro. The amount of specific seminal plasma proteins is related to fertility and thereby provides an additional semen evaluation method. For the use of a given semen test the specific in vitro condition has to be considered. In addition, the evaluated criteria relevant for the process of fertilization need to be defined. The combination of selected semen tests gives a higher accuracy for the prediction of fertilizing capacity compared with a single test.     

Diagnostic Methods for Evaluation of Stallion Subfertility: A Review

Classically, evaluation of the breeding stallion for reduced fertility has relied on physical examination of the reproductive system, as well as evaluation of sperm number, motility, and morphology. Over the past 20 years, a number of other diagnostic methods have become available to facilitate reproductive evaluation of the stallion. Specifically, ultrasound imaging has provided much-improved diagnostic methods for evaluation of the external and internal genitalia of the stallion, and these methods have now become routine in evaluation of the stallion. Biochemical analyses of semen can provide useful information for diagnosis of azoospermia (determination of alkaline phosphatase), detection of urine contamination, or changes in pH. Numerous sperm function assays provide information concerning subcellular compartments of the sperm including the plasma membrane, DNA, acrosome, and mitochondria. Data correlating these functional assays with fertility in the stallion are limited in most cases, with the exception of the sperm chromatin structure assay. Finally, the recent sequencing of the equine genome offers the possibility of both marker-assisted selection for fertility traits and more specific information about genetic mutations that may be associated with differing levels of fertility in the stallion.     

Vaccination against the avian infectious bronchitis virus affects sperm concentration, sperm quality and blood testosterone concentrations in cockerels

1. It was previously found that cockerels vaccinated with live attenuated avian infectious bronchitis virus (AIBV) have decreased serum testosterone concentrations, epididymal stones and reduced fertility. The objectives of this study were twofold: to determine if reduced fertility following vaccination with live attenuated virus was the result of reduced sperm concentration or reduced sperm quality and to determine if vaccination with a killed strain of virus caused a similar reduction in sperm function in vivo. 2. Specific-pathogen-free Single Comb White Leghorn cockerels were divided into three treatment groups: no vaccination (NONVAC), vaccination with killed AIBV virus (KVAC) or vaccination with live attenuated AIBV virus (LVAC). Semen was collected daily from 17 to 27 weeks of age, and semen quality was assessed frequently by analysing sperm concentration, viability, motility, and ability to reach and interact with the ovum in vivo. Blood plasma was assayed for testosterone concentration. 3. Differences in sperm analysis among treatment groups were limited. Sperm viability was increased in NONVAC during week 20 which then decreased in week 22 when compared to vaccinated cockerels. Acrosome damage was increased in vaccinated cockerels in week 22, and decreased in weeks 25 and 27 when compared to controls, which correlate to the period of epididymal stone development. Plasma testosterone concentrations and sperm concentrations among treatment groups were different only at 16 and 19 weeks of age, respectively. There were no differences across treatment groups in sperm mobility through Accudenz or in numbers of sperm holes in perivitelline membranes of eggs following insemination with semen from 27-week-old cockerels. No differences were observed in viability or acrosome integrity between cockerels with and without epididymal stones within treatment groups. 4. In conclusion, pre-pubertal vaccination against AIBV and subsequent epididymal stone formation had a limited effect on sperm concentration, sperm quality and plasma testosterone concentrations. Vaccination with killed AIBV vaccine did not diminish effects on sperm function in vivo.     

Fertility and sperm quality of broiler breeder males infected with subgroup J avian leukosis virus

In order to assess the effects of subgroup J avian leukosis virus (ALV-J) on semen quality, broiler breeder males were separated by ALV-J status (ALV-J positive = POS, ALV-J negative = NEG) at 44 wk of age. Of the 249 males originally placed at 1 day of age, 101 (40.6%) died by 43 wk of age. Observations of tumor expression and high mortality suggest that many of the males that died prior to 44 wk of age were infected with ALV-J. From 47 to 56 wk of age, hens were inseminated every third week with 7.5 x 10(7) sperm. Fertility and hatch data were collected by incubating eggs laid during the 2 wk postinsemination (WPI). The number of sperm that penetrated the perivitelline membrane of the ovum was determined from eggs laid on the eighth day postinsemination. Sperm mobility index (SMI) was determined at 58 and 60 wk of age from all males producing semen. Whereas SMI and sperm hole penetration measurements indicated that the sperm quality from treatments POS and NEG were similar, fertility was significantly greater in the POS treatment during the first (89.0% vs. 79.0%) and second WPI (59.3% vs. 45.0%). However, because of numerically higher hatch of fertile from the NEG group, the percentage of hatch of eggs set was similar between groups. These data suggest that ALV-J status of caged males has no influence on sperm quality or hatchability of eggs.     

Accessory sperm: their importance to fertility and embryo quality, and attempts to alter their numbers in artificially inseminated cattle.

Accessory sperm number and its relationship to fertilization and embryo quality was evaluated in cattle after nonsurgical recovery of ova or embryos 6 d after insemination. Efforts to alter accessory sperm number per ovum included 1) blockage of retrograde sperm loss at insemination using a modified insemination device, 2) elevated sperm number per inseminate (40 x 10(6) vs 20 x 10(6], and 3) alteration in semen quality (percentage of viable and morphologically normal sperm in the inseminate). None of these efforts affected accessory sperm number per ovum or embryo. However, blockage of retrograde semen flow for 3 h or use of semen of below-average quality (decreased percentage of viable and morphologically normal sperm) resulted in significant decreases in number of viable embryos and increases in number of degenerate embryos and unfertilized ova compared with conventional insemination (P less than .03) and use of semen with an average percentage of viable and morphologically normal sperm (P less than .06). Number of accessory sperm per embryo or ovum was positively related to fertilization and embryo quality (P less than .05). Mean accessory sperm +/- SD and the median value (in parentheses) for unfertilized ova, degenerate embryos, and embryos classified fair to poor and excellent to good were, respectively, .3 +/- .8 (0), 5.4 +/- 8.9 (1.0), 15.8 +/- 28.6 (3.5), and 16.9 +/- 29.5 (5.0). We conclude that efforts to improve accessory sperm numbers per embryo or ovum failed and that high variation and skewness of accessory sperm toward 0 may make median values more meaningful than means.(ABSTRACT TRUNCATED AT 250 WORDS)     

The Predictive Value of Semen Analysis in the Evaluation of Stallion Fertility

Pregnancy rates in managed horse populations depend on the innate fertility of the mares and stallions involved and on the quality of breeding management. Of course, because a single stallion usually mates many mares, stallion fertility is a critical factor in the overall success of a breeding program. Unfortunately, accurate evaluation of stallion fertility per se requires a large number of normal mares to be mated and is necessarily retrospective. Rather, the ideal is to predict fertility in advance of the stallion's breeding career, and this is currently attempted by way of a thorough physical examination and a routine analysis of semen quality. However, while such a ‘breeding soundness examination’ identifies stallions that clearly lack the capacity for adequate fertility, it is of limited use for predicting the level of fertility and fails to identify some seriously sub‐fertile animals. Similarly, while various sperm function tests (e.g., sperm head morphometry, the hypoosmotic swelling test, glass wool‐sephadex filtration, progesterone receptor exposure) have been shown to correlate fairly well with fertility in the field, most examine only a single or a narrow range of the attributes that a sperm must possess if it is to fertilize an oocyte in vivo, and are thus more useful for identifying specific causes of sub‐fertility than for predicting the level of fertility. On the other hand, combining the results of the various sperm function tests does improve the reliability of fertility estimation and current research is therefore concentrated on identifying a range of tests that covers as many important sperm attributes as possible but that can be performed rapidly and cheaply. In this respect, flow‐cytometry has proven to be an ideal tool because it allows the objective, rapid and simultaneous analysis of a number of properties in a large number of sperm. Moreover, stains are available for an increasing range of sperm characteristics including viability, capacitation and acrosome status, mitochondrial activity and chromatin integrity. Flow‐cytometric analysis of sperm with appropriate probes thus offers considerable promise for the prediction of stallion fertility.     

The relationship of porcine sperm zona-binding ability to fertility

Several laboratory assays have been designed to assess the fertility potential of a semen sample before insemination, but none have been consistent and accurate predictors of fertility. To determine whether zona-binding ability may be a useful fertility predictor, we validated and used an in vitro competitive assay to measure the ability of porcine sperm to bind to the zona pellucida. The zona-binding ability of sperm from 11 boars that exhibited a broad range in average litter size and farrowing rate was determined. Sperm from each boar were compared directly with sperm from eight other boars in a systematic, pairwise fashion. Sperm from two semen samples were labeled with fluorophores at concentrations that did not affect motility or zona-binding ability. An equal number of labeled sperm from each boar was coincubated with homologous oocytes. Least squares means from analysis of variance were used to rank boars based on zona-binding ability. The competitive assay was effective in establishing a ranking of the boars (R2 = 0.62). Furthermore, there was a correlation between zona-binding ability and fertility when estimated by average litter size (r = 0.64, P < 0.05) but not when estimated by farrowing rate (r = -0.28). The explanation for this difference was that litter size and farrowing rate were poorly correlated (r = 0.14). In conclusion, a competitive zona-binding assay distinguished boars that sired either small or large litters. Competitive zona-binding ability may be useful for identifying boars with reduced fertility that produce smaller litters following insemination.     

Effect of Ram Age on Structural and Functional Competence of Frozen–Thawed Spermatozoa in Dairy Sheep

The objectives of this study were to investigate the influence of ram age on structural and functional competence of frozen–thawed spermatozoa and to test the hypothesis that increasing number of sperm bound to the zona pellucida in vitro was associated with decreasing in vivo fertility of frozen semen. Rams were allocated into two groups. Each group consisted of five rams aged either 1–2 years (young) or 4–5 years (mature). Three successive ejaculates were collected from each ram using an artificial vagina. Only ejaculates of ≥ 2.5 × 10⁹ sperm/ml and 80% sperm progressive motility were pooled per ram, diluted with Bioxcell^® medium and frozen in 0.25 ml straws. The end points of post‐thawing semen evaluation were computer‐assisted cell motility analysis, sperm capacitation (chlortetracycline assay), simultaneous assessment of plasma membrane integrity, mitochondrial membrane potential and condensation status of nucleus, per‐cell analysis of lipid peroxidation using C11‐BODIPY^581/591, sperm‐hemizona binding (HZB) ability and sperm fertility after laparoscopic insemination of ewes (n = 114) in the progestagen‐synchronized oestrus. The results showed that mature rams had significantly lower values of sperm hyperactivated motility and peroxidized sperm, higher percentages of live non‐capacitated sperm and sperm cells with intact plasma membrane, functional mitochondria and condensed chromatin, as well as, greater lambing rate and ewe prolificacy. Sperm HZB binding ability was higher (p < 0.05) for young than for mature rams. Significant correlations were found between number of spermatozoa bound to the zona pellucida and semen fertility (r = ?0.63 to ?0.71). In conclusion, mature rams have better semen quality and in vivo fertility than young rams. Cryocapacitation can be involved in decreasing ram semen fertility as evidenced by the high number of spermatozoa bound to the zona pellucida in vitro.     

Storage of sperm in the uterovaginal junction and its incidence on the numbers of spermatozoa present in the perivitelline layer of hens' eggs

1. The numbers of spermatozoa found in the perivitelline layer (perivitelline spermatozoa) of hens' eggs during a 14-d period after insemination were found to be log-dose dependent (r = 0.99) on the quantities of spermatozoa inseminated intravaginally in these hens (50, 100, 200 or 400 million/female). 2. Highly significant correlations were also observed between the perivitelline spermatozoa and the proportion of uterovaginal sperm-storage tubules containing spermatozoa on day 14 after insemination. 3. These data confirm that the number of perivitelline spermatozoa in eggs laid on day 2 after artificial insemination (AI) are highly correlated with the mean percentages of fertility of its duration over a 14-d or 24-d period. As a consequence, eggs laid by the 10% highest or the 10% lowest females primarily classified on the basis of this variable exhibited on average 99% or 49.7% fertility, respectively, over a two-week period after AI.     

Application of the Sperm Mobility Assay to Primary Broiler Breeder Stock

A new quantitative trait affecting male fertility was discovered in the 1990s. The term sperm mobility denotes the net movement of a sperm cell population against resistance at body temperature. Even though sperm cells are self-propelled DNA delivery vehicles, their self-propulsive nature is neither uniform among sperm within an ejaculate nor among males within flocks. Such variation is evident when semen quality is evaluated by sperm penetration of an Accudenz solution, hence the term sperm mobility assay. It is noteworthy that populations showing modest variation with respect to semen volume or sperm concentration often show considerable variation with respect to sperm mobility. Likewise, it is noteworthy that broiler breeder fertility is a function of sperm mobility phenotype when hens are inseminated artificially. This article outlines the following: 1) a series of experiments in which the sensitivity of the commercial sperm mobility assay was improved using semen donors from lines of chickens selected for either low or high sperm mobility and 2) the application of the improved technique to pedigree broiler breeders. Male fertility is subject to genetic selection when sperm mobility is the selection criterion. Therefore, sperm mobility may be a useful trait for improving broiler breeder reproductive efficiency.     

Sperm-egg penetration in laying breeder flocks: a technique for the prediction of fertility.

1. An experiment was conducted to evaluate indices of fertility including the sperm penetration (SP) assay as a technique for the prediction of fertility. Forty-eight males consisting of White Leghorn (WL), New Hampshire (NH), Iraqi Brown (IBr) and Iraqi Barred (IBa) (12 males each) and 64 WL hens were divided at random into 4 groups of 4 replicates of 3 males and 4 females each. 2. At the beginning of each week semen was collected from males and pooled by breed of male. Hens in each breeding group were inseminated once weekly, by breeding group, for 4 consecutive weeks with pooled semen from WL, NH, IBr and IBa males (WLxWL, NHxWL, IBrxWL and IBaxWL). 3. The differences in percentage of dead sperm, acrosomal abnormalities, mass motility, individual motility and spermatocrit between the experimental breeds demonstrated the superiority of WL and NH males in all these quantitative characters of the semen. On the other hand, WL hens inseminated with spermatozoa from NH males had significantly more sperm-egg penetration (SP) holes than WL hens inseminated with spermatozoa from other breeds of males. The breed of males used for insemination affected fertility, hatchability and embryonic mortality. 4. The highest fertility and hatchability and lowest embryonic mortality were observed in eggs laid by hens inseminated with spermatozoa from WL and NH males in comparison with hens inseminated with spermatozoa from Iraqi males. 5. There was a strong positive correlation between SP values and fertility for WLxWL, NHxWL, IBrxWL and IBaxWL. The correlation for all breeds combined was also significant. In addition, SP was also positively correlated with hatchability and negatively correlated with embryonic mortality.     

哺乳动物精子检测技术研究进展

普通光学显微镜检测精液存在主观性、可变性、分析的精子数量少和与受精能力相关性差等缺点。近些年来,一些新的技术用于检测精子,可以更加细致地评价精子的特性。荧光染色技术可以用于评价精子的特殊性质和功能,包括质膜完整性、获能状态和顶体状态。联合使用荧光染料,可以同时检测精子几种功能特点。流式细胞仪可以在短时间内分析大量的经荧光标记的精子。计算机辅助精子分析系统可以提供精子活力和形态学上客观的和详细的信息。通过检测精子与透明带或者输卵管上皮附着、精子穿透卵母细胞,可以获得精子受精能力的信息。未来的研究方向仍是寻找有效的预测精子受精能力的参数。     

高原鼠兔洞系特征及功能研究

通过在甘南玛曲900个洞口的实地调查,对高原鼠兔的洞系特征(洞口数量、位置、朝向、格局,洞道结构等)进行了系统研究。结果表明,高原鼠兔不同洞口朝向间的洞口数存在显著差异,其中全阴、半阴、全阳间的差异极显著;洞口直径与洞口朝向无相关性;洞口斜度≤55°的洞口主要集中在SW、SE和S 3个方向,占洞口总数的48.6%,洞口斜度＞55°的洞口主要集中在NW、NE和N 3个方向,占洞口总数的52.1%;S向和偏S向的洞口温度显著高于N向和偏N向的洞口,W向和偏W向洞口温度普遍高于E向和偏E向洞口,前者最高温差可达13.2℃,后者最高温差为6.0℃。由上述可见,高原鼠兔的洞系建筑特点是对高原环境的一种适应性选择,除了常规意义上的栖居和避险等基本功能而外,还兼顾了洞内温度、对流和抵御寒风的利弊权衡。