Reproductive interference between honey bee species in artificial sympatry

Reproductive isolation between closely related species is often incomplete. The Western honey bee, Apis mellifera, and the Eastern hive bee, A. cerana have been allopatric for millions of years, but are nonetheless similar in morphology and behaviour. During the last century the two species were brought into contact anthropogenically, providing potential opportunities for interspecific matings. Hybrids between A. mellifera and A. cerana are inviable, so natural interspecific matings are of concern because they may reduce the viability of A. cerana and A. mellifera populations – two of the world's most important pollinators. We examined the mating behaviour of A. mellifera and A. cerana queens and drones from Caoba Basin, China and Cairns, Australia. Drone mating flight times overlap in both areas. Analysis of the spermathecal contents of queens with species-specific genetic markers indicated that in Caoba Basin, 14% of A. mellifera queens mated with at least one A. cerana male, but we detected no A. cerana queens that had mated with A. mellifera males. Similarly, in Cairns, no A. cerana queens carried A. mellifera sperm, but one third of A. mellifera queens had mated with at least one A. cerana male. No hybrid embryos were detected in eggs laid by interspecifically-mated A. mellifera queens in either location. However A. mellifera queens artificially inseminated with A. cerana sperm produced inviable hybrid eggs, or unfertilised drones. This suggests that reproductive interference will impact the viability of honey bee populations wherever A. cerana and A. mellifera are in contact. This article is protected by copyright. All rights reserved.

A Need for FSH in Maintaining Fertility of Adult Male Subhuman Primates

Adult fertile male bonnet monkeys (Macaca radiata) were continuously deprived of endogenous follicle stimulating hormone (FSH) support for 240 days by injecting them with 1 ml of characterized monkey antiserum to oFSH every 48 hr; control monkeys received during the same period normal monkey serum instead. Testicular function was assessed at periodic intervals by (a) carrying out differential counting of sperm in the ejaculate obtained and (b) determining the hyaluronidase activity as well as in vitro 3H thymidine incorporation into DNA of testicular tissue removed at biopsy. Both the quality (viability and motility) of the sperms voided and the total sperm counts showed marked decreases as a function of time of immunization, the first significant reduction being noted by 100 days. FSH deprivation affected both the biochemical parameters used to test testicular functionality they being reduced at ∼200 days by 50%-60%. The fertility of these monkeys was evaluated at periodic times after 90 days of treatment by means of mating studies. FSH deprivation had rendered the monkeys incapable of impregnating any of the females used. Testosterone and luteinizing hormone (LH) levels remained unchanged following FSH antiserum injection. With cessation of antiserum treatment testicular function and fertility were completely restored to normalcy, indicating that the observed effect was specifically due to FSH deprivation. This study thus provides conclusive evidence for the involvement of FSH in maintenance of testicular function and fertility in the adult male primate.

Three-dimensional reconstruction of black tiger prawn (Penaeus monodon) spermatozoa using serial block-face scanning electron microscopy

Serial Block-Face Scanning Electron Microscopy (SBF-SEM) was used in this study to examine the ultrastructural morphology of Penaeus monodon spermatozoa. SBF-SEM provided a large dataset of sequential electron-microscopic-level images that facilitated comprehensive ultrastructural observations and three-dimensional reconstructions of the sperm cell. Reconstruction divulged a nuclear region of the spermatophoral spermatozoon filled with decondensed chromatin but with two apparent levels of packaging density. In addition, the nuclear region contained, not only numerous filamentous chromatin elements with dense microregions, but also large centrally gathered granular masses. Analysis of the sperm cytoplasm revealed the presence of degenerated mitochondria and membrane-less dense granules. A large electron-lucent vesicle and "arch-like" structures were apparent in the subacrosomal area, and an acrosomal core was found in the acrosomal vesicle. The spermatozoal spike arose from the inner membrane of the acrosomal vesicle, which was slightly bulbous in the middle region of the acrosomal vesicle, but then extended distally into a broad dense plate and to a sharp point proximally. This study has demonstrated that SBF-SEM is a powerful technique for the 3D ultrastructural reconstruction of prawn spermatozoa, that will no doubt be informative for further studies of sperm assessment, reproductive pathology and the spermiocladistics of penaeid prawns, and other decapod crustaceans. J. Morphol., 2016. (c) 2016 Wiley Periodicals, Inc.

Pre- and post-copulatory sexual selection in the least killifish, Heterandria formosa

It has been only recently realized that sexual selection does not end at copulation but that post-copulatory processes are often important in determining the fitness of individuals. In this thesis, I experimentally studied both pre- and post-copulatory sexual selection in the least killifish, Heterandria formosa. I found that this species suffers from severe inbreeding depression in male reproductive behaviour, offspring viability and offspring maturation times. Neither sex showed pre-copulatory inbreeding avoidance but when females mated with their brothers, less sperm were retrieved from their reproductive system compared to the situation when females mated with unrelated males. Whether the difference in sperm numbers is due to female or male effect could not be resolved. Based on theory, females should be more eager to avoid inbreeding than males in this species, because females invest more in their offspring than males do. Inbreeding seems to be an important part of this species biology and the severe inbreeding depression has most likely selected for the evolution of the post-copulatory inbreeding avoidance mechanism that I found. In addition, I studied the effects of polyandry on female reproductive success. When females mated with more than one male, they were more likely to get pregnant. However, I also found a cost of polyandry. The offspring of females mated to four males took longer to reach sexual maturity compared to the offspring of monandrous females. This cost may be explained by parent-offspring conflict over maternal resource allocation. In another experiment, in which within-brood relatedness was manipulated, offspring sizes decreased over time when within-brood relatedness was low. This result is partly in accordance with the kinship theory of genomic imprinting. When relatedness decreases, offspring are expected to be less co-operative and demand fewer resources from their mother, which leads to impaired development. In the last chapter of my thesis, I show that H. formosa males do not prefer large females as in other Poeciliidae species. I suggest that males view smaller females as more profitable mates because those are more likely virgin. In conclusion, I found both pre- and post-copulatory sexual selection to be important factors in determining reproductive success in H. formosa.

Pentoxifylline induces hyperactivation and acrosome reaction in spermatozoa of golden hamsters: changes in motility kinematics

Pentoxifylline (PF) is used to enhance motility of spermatozoa from infertile human subjects. We have previously shown that 0.45 mM PF improved capacitation of spermatozoa and fertilization of oocytes in vitro in hamsters. The present study was carried out to assess PF- induced changes in motility kinematics of hamster spermatozoa by a computer-aided sperm analyser (CASA) and determine the timing of onset of hyperactivation (HA) and acrosome reaction (AR) in PF-treated spermatozoa. Motility kinematics were analysed by CASA for 0-8 h in the absence or presence of 0.45 mM PF in Tyrode's medium supplemented with lactate, pyruvate and polyvinyl alcohol (TLP-PVA) or in TLP-PVA with bovine serum albumin (TALP-PVA). Conventional assessment was also made on the percentage of motility and quality of motility of spermatozoa; values were expressed as sperm motility index (SMI). Both in TALP-PVA and TLP-PVA, PF markedly increased SMI, especially the quality of motility (P < 0.02) by 2-3 h which was sustained up to 6 h. The motility kinematic data of PF-treated spermatozoa in TALP-PVA showed that average path velocity, curvilinear velocity and amplitude of lateral head displacement significantly (P < 0.05) increased as early as 2 h, with the expected decrease in straightness (STR) and linearity (LIN). Similar changes were also observed with PF-treated spermatozoa in TLP-PVA. Moreover, the percentage of hyperactivated spermatozoa in PF-treated samples was significantly (P < 0.001) higher than the untreated control at 2 h. To determine whether PF could induce AR, independent of bovine serum albumin, quantitative AR was assessed by observing the presence or absence of acrosomal cap on viable spermatozoa. PF significantly (P < 0.001) increased the percentage of AR as early as 2 h, reaching maximum at 4 h both in TALP-PVA (P < 0.05) and in TLP-PVA (P < 0.001). These results show that, in hamsters, PF induces early onset (by 2 h) of HA and AR and increases the proportion of spermatozoa undergoing physiological maturation.

Use of norethisterone and estradiol in mini doses as a contraceptive in the male : Efficacy studies in the adult male bonnet monkey (Macaca radiata)

Administration of norethisterone (NET) or NET + estradiol benzoate using an Alzet minipump or as once-a-month intramuscular injection of their depot forms, NET-enanthate (NET-EN) and estradiol valerate (E-val), resulted in azoospermia in all monkeys (n = 13) within 60 to 150 days of treatment. Although addition of depot form of testosterone (T, 20 mg/month) to the regimen restored the behavioral response typical of a normal male, it did not reverse the azoospermic state. Serum T (heightened nocturnal) levels were significantly reduced (> 85%, p < 0.001) in all the treated groups. Evidence for blockade in spermatogenesis following treatment was obtained by DNA flow cytometry. Following withdrawal of treatment, the T level was restored to normalcy within 15 days but 120 days more were required for the animals to exhibit normal sperm counts. In conclusion, the efficacy of once-a-month injection of relatively low doses of NET-EN + E-Val to bring about azoospermia in monkeys, in a relatively short time, has been demonstrated. As the results are uniform and reproducible, it appears desirable that this steroid regimen be tested in man for its contraceptive efficacy.

Micromolar concentration of pentoxifylline improves development in vitro of hamster 8-cell embryos: conrmation of biological viability by embryo transfer

The inßuence of the sperm motility stimulant pentoxifylline (PF) on preimplantation embryo development in hamsters was evaluated. Eight-cell embryos were cultured in hamster embryo culture medium (HECM)-2, with or without PF (0· 0233·6 mM). There was 90%, 37% and 29% inhibition of blastocyst development by 3·6 (used for human sperm), 0·9 and 0 ·45 mM PF, respectively. However, 23 µM PF (exposed to hamster oocytes during IVF) signicantly (P < 0·05) improved blastocyst development (63· 6% v. 51· 8%); morulae development was, however, not curtailed by 0·45 mM or 0·9 mM PF (51·8%±6·0 or 50·5%±11·3, respectively). Post-implantation viability of PF-treated embryos was assessed by embryo transfer; 43% of 80 PF-treated embryos implanted compared with 40% of 79 control embryos. Of the 9 recipients, 6 females delivered pups (19, i.e. 16% of transferred embryos or 53% of implanted embryos). These data show that in hamsters, continuous presence of PF at 0·45-3·6 mM is detrimental to 8-cell embryo development whereas 23 µM PF improves the development of embryos to viable blastocysts which produce live offspring.

Middle aged wasps mate through most of the year, without regard to body size, ovarian development and nestmateship: a laboratory study of the primitively eusocial wasp Ropalidia marginata

We studied the mating behaviour of the primi-tively eusocial wasp Ropalidia marginata and the factors that may influence sperm transfer. By introducing a male and a female R. marginata into ventilated transparent plastic boxes, we were able to observe mating behaviour, and it involved mounting and short or long conjugation of the wasps. Dissection of female wasps after the observation indicated that long conjugation is a good behavioural predictor of sperm transfer. This finding makes it possible to obtain mated females without dissecting them every time. We tested the effect of age, season, relatedness, body size and female's ovarian status on mating. Under laboratory conditions, mating success declined rapidly below and above the ages 5-20 days. Within this age range mating success was significantly low in December compared to other months tested. There was no nestmate discrimination, and there was no influence of male and female body size or of the ovarian state of the female on the probability of sperm transfer.

Outcome of singleton pregnancy after assisted reproductive treatment

Singleton pregnancies achieved by means of assisted reproductive treatment (ART) are associated with increased obstetric and neonatal risks in comparison with spontaneously conceived singleton pregnancies. The impact of infertility- and treatment-related factors on these risks is not properly understood. In addition, the psychological effects of infertility and its treatment on the experience of pregnancy have scarcely been studied. Thus, the aim of the present study was to evaluate the importance of infertility- and treatment-related factors on prediction of pregnancy outcome, obstetric and neonatal risks, fear-of-childbirth and pregnancy-related anxiety. The subjects consisted of infertile women who achieved a singleton pregnancy by means of in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI). The control groups comprised spontaneously conceiving women with singleton gestations. Early pregnancy outcome was assessed by means of assay of serum human chorionic gonadoptrophin (hCG) in single samples. Other outcome data were collected from patient records, national Health Registers and via prospective questionnaire surveys. Viable pregnancies were associated with significantly higher serum hCG levels 12 days after embryo transfer than non-viable pregnancies. Among singleton pregnancies, aetiological subgroup, treatment type or the number of transferred embryos did not impair the predictive value of single hCG assessment. According to the register-based data, age-, parity- and socioeconomic status- adjusted risks of gestational hypertension, preterm contractions and placenta praevia were more frequent in the ART pregnancies than in the control pregnancies. Significantly higher rates of induction of delivery and Caesarean section occurred in the ART group than in the control group. The risks of preterm birth and low birth weight (LBW) were increased after ART pregnancy. Duration or aetiology of infertility, treatment type (fresh or frozen IVF or ICSI) or rank of treatment did not contribute to the risks of preterm birth or LBW. In addition, the risks of preterm birth and LBW remained elevated in spite of of the number of transferred embryos. Although mean duration of pregnancy was shorter and mean birth weight lower in the ART pregnancies than in the control pregnancies, these differences were hardly of clinical significance. Fear-of-childbirth and pregnancy-related anxiety were equally common to women conceiving by means of ART, or spontaneously. Partnership of five to ten years appeared to be protective as regards severe fear-of-childbirth, whereas long preceding infertility (≥ seven years) had the opposite effect. In conclusion, an early hCG assessment maintained its good predictive value regardless of infertility- or patient-related factors. Further, we did not recognise any infertility- or patient-related factors that would expose infertile women to increased obstetric or neonatal risks. However, a long period of infertility was associated with severe fear-of-childbirth.

Transition to parenthood after assisted reproductive treatment: Follow-up study of singleton pregnancies

Infertility treatments are relatively easily available in most Western countries today, but the psychological consequences of these high-tech treatments have scarcely been addressed. The purpose of this controlled longitudinal study was to explore the early environment of the infant born by assisted reproductive treatment (ART). We focused on the parents mental well-being, marital relations and experience of parenting. In addition to this, we assessed parent child interaction and parents mental representations of their child after long-standing infertility and several unsuccessful ART attempts. The subjects were infertile couples who achieved a singleton pregnancy by in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). The control group comprised of spontaneously conceiving couples with singleton pregnancies. ART women showed fewer depressive symptoms than controls during pregnancy and after delivery, but the difference vanished by the end of the child s first year. ART men consistently had lower levels of anxiety symptoms, sleeping difficulties, and social dysfunction than control men. Control women experienced a decrease in dyadic consensus during the child s first year, which did not happen among ART women. After the child was born, ART men reported a higher level of sexual affection compared with control men. Psychic symptoms and stressful life events were differently related to marital relations in ART and control groups. The parenting experiences of ART mothers were in general at a higher level, compared with controls, and they changed in a positive direction during the child s first year. Fathering experiences were at the same level in both groups, and they changed positively in both groups by the end of the child s first year. The parenting experiences of ART mothers and fathers were more resilient to certain child-related stressors than those of control group. Both mothers and fathers with long-term infertility showed more sensitive behaviour with their child in toddler-age than in infancy. Correspondingly, children s cooperation increased. Mothers often mentioned a fear of miscarriage and difficulty in creating representations of the child during pregnancy. Descriptions of the infants were mainly rich, vivid and loaded with positive features. In conclusion, ART parents in general seem to adapt well to the transition to parenthood. Former infertility and ART do not seem to constitute a risk for parents mental health, marital relations or experience of parenting. Even longstanding infertility with several unsuccessful treatment attempts did not create a risk as regards parenting behaviour or parents mental representations of their child. In this group, however, women were found to have fear for losing the child and difficulty in creating representations of the child during pregnancy, which in some cases may indicate need for psychosocial support. Even though our results are encouraging, infertility and infertility treatments are generally considered as a stressful experience. It is a challenge for health authorities to recognize those couples who need professional help to overcome the distressing experiences of infertility and ART.

Oligosaccharides modulate the apoptotic activity of glycodelin

GlycodelinA (GdA), a multifunctional glycoprotein secreted at high concentrations by the uterine endometrium during the early phases of pregnancy, carries glycan chains on asparagines at positions N28 and N63. GdA purified from amniotic fluid is known to be a suppressor of T-cell proliferation, an inducer of T-cell apoptosis, and an inhibitorof sperm-zona binding in contrast to its glycoform, glycodelinS (GdS), which is secreted by the seminal vesicles into the seminal plasma. The oligosaccharide chains of GdA terminate in sialic acid residues, whereas those of GdS are not sialylated but are heavily fucosylated. Our previous work has shown that the apoptogenic activity of GdA resides in the protein backbone, and we have also demonstrated the importance of sialylation for the manifestation of GdA-induced apoptosis. Recombinant glycodelin (Gd) expressed in the Sf21 insec cell line yielded an apoptotically active Gd; however, the same geneexpressed in the insect cell line Tni produced apoptotically inactive Gd, as observed with the gene expressed in the Chinese hamster ovary(CHO) cell line and earlier in Pichia pastoris. Glycan analysis of the Tni and Sf21 cell line-expressed Gd proteins reveals differences in their glycan structures, which modulate the manifestation of apoptogenic activity of Gd. Through apoptotic assays carried out with the wild-type (WT) and glycosylation mutants of Gd expressed in Sf21 and Tni cells before and after mannosidase digestion, we conclude that the accessibility to the apoptogenic region of Gd is influenced by the size of the glycans.

Tyrphostin-A47 inhibitable tyrosine phosphorylation of flagellar proteins is associated with distinct alteration of motility pattern in hamster spermatozoa

To acquire fertilizing potential, mammalian spermatozoa must undergo capacitation and acrosome reaction. Our earlier work showed that pentoxifylline (0.45 mM), a sperm motility stimulant, induced an early onset of hamster sperm capacitation associated with tyrosine phosphorylation of 45-80 kDa proteins, localized to the mid-piece of the sperm tail. To assess the role of protein tyrosine phosphorylation in sperm capacitation, we used tyrphostin-A47 (TP-47), a specific protein tyrosine kinase inhibitor. The dose-dependent (0.1-0.5 mM) inhibition of tyrosine phosphorylation by TP-47 was associated with inhibition of hyperactivated motility and 0.5 mM TP-47-treated spermatozoa exhibited a distinct circular motility pattern. This was accompanied by hypo-tyrosine phosphorylation of 45-60 kDa proteins, localized to the principal piece of the intact-sperm and the outer dense fiber-like structures in detergent treated-sperm. Sperm kinematic analysis (by CASA) of spermatozoa, exhibiting circular motility (at 1st hr), showed lower values of straight line velocity, curvilinear velocity and average path velocity, compared to untreated controls. Other TP-47 analogues, tyrphostin-AG1478 and -AG1296, had no effect either on kinematic parameters or sperm protein tyrosine phosphorylation. These studies indicate that TP-47-induced circular motility of spermatozoa is compound-specific and that the tyrosine phosphorylation status of 45-60 kDa flagellum-localized proteins could be key regulators of sperm flagellar bending pattern, associated with the hyperactivation of hamster spermatozoa.

Interaction of metal ions with nucleic acids and related compounds. II. Studies on Au(III)-nucleic acid system

The nature of interaction of Au(III) with nucleic acids was studied by using methods such as uv and ir spectrophotometry, viscometry, pH titrations, and melting-temperature measurements. Au(III) is found to interact slowly with nucleic acids over a period of several hours. The uv spectra of native calf-thymus DNA 9pH 5.6 acetate buffer containing (0.01M NaCIO4) showed a shift in λ max to high wavelengths and an increase in optical density at 260 nm. There was a fourfold decrease in viscosity (expressed as ηsp/c). The reaction was faster at pH 4.0 and also with denatured DNA (pH 5.6) and whole yeast RNA (pH 5.6). The order of preference of Au(III) (as deduced from the time of completion of reaction) for the nucleic acids in RNA > denatured DNA > DNA. The reaction was found to be completely reversible with respect KCN. Infrared spectra of DNA-Au(III) complexes showed binding to both the phosphate and bases of DNA. The same conclusions were also arrived at by melting-temperature studies of Au(III)-DNA system. pH titrations showed liberation of two hydroxylions at r = 0.12 [r = moles of HAuCl4 added per mole of DNA-(P)] and one hydrogen ion at r = 0.5. The probable binding sites could be N(1)/N(7) of adenine, N(7) and/or C(6)O of guanine, N(3) of cytosine and N(3) of thymine. DNAs differing in their (G = C)-contents [Clostridium perfingens DNA(G = C, 29%), salmon sperm DNA (G + C, 42%) and Micrococcus lysodeikticus DNA(G + C, 29%), salmon sperm DNA (G = C, 72%)] behaved differently toward Au(III). The hyperchromicity observed for DNAs differing in (G + C)-content and cyanide reversal titrations indicate selectivity toward ( A + T)-rich DNA at lw values of r. Chemical analysis and job's continuous variation studies indicated the existence of possible complexes above and below r = 1. The results indicate that Au(III) ions probably bind to hte phosphate group in the initial stages of the reaction, particularly at low values of r, and participation of the base interaction also increases. Cross-linking of the two strands by Au(III) may take place, but a complete collapse of the doulbe helix is not envisaged. It is probable that tilting of the bases or rotaiton of the bases around the glucosidic bond, resulting in a significant distrotion of the double helix, might take place due to binding of Au(III) to DNA.

Afrikkalaisen sikaruton mahdollisia maahantuloreittejä

Afrikkalainen sikarutto on lakisääteisesti vastustettava helposti leviävä sikojen ja villisikojen virustauti, jolla on myös vakavia sosioekonomisia vaikutuksia. Akuutissa tautimuodossa eläimillä esiintyy syömättömyyttä, korkeaa kuumetta, verenpurkaumia iholla, veristä ulostetta sekä mahdollisesti ripulia. Kuolleisuus on lähes 100 % ja tauti johtaa kuolemaan 7-10 vrk tartunnan jälkeen. Tauti ei tartu ihmisiin. Tautia esiintyy sekä kesy- että villisioissa suurimmassa osassa Saharan eteläpuolista Afrikkaa ja Sardiniassa. Vuodesta 2007 lähtien tautia on esiintynyt Kaukasuksen alueella ja vuonna 2011 lähellä Suomen rajaa: Leningradin alueella ja Kuolan niemimaalla. Tässä riskiprofiilissa kartoitetaan reitit ja tapahtumasarjat, jotka voivat johtaa siihen, että afrikkalainen sikarutto tulee Suomeen ensimmäisen kerran. Näistä oleellisimmat ovat: maahantulo infektioalueella matkustaneiden ihmisten mukana, infektoituneen lihan tai lihatuotteen mukana, elävien kesysikojen ja sperman mukana, kontaminoituneiden eläinkuljetusajoneuvojen mukana, kansainvälisen liikenteen ruokajätteen mukana ja Suomeen vaeltavan infektoituneen villisian mukana. Tilatason tautisuojaus sekä tehokas ja kohdennettu tiedottaminen taudin vaaroista ovat avainasemassa, kun halutaan suojata Suomen sikaelinkeinoa afrikkalaiselta sikarutolta.

Impaired spermatogenesis in Finnish boars and bulls

Maintenance of breeding efficiency and high semen quality is essential for reproductive success in farm animals. Early recognition of possible inheritable factors causing infertility requires constant attention. This thesis focuses on describing different manifestations of impaired spermatogenesis, their impact on fertility and partly also their incidence in populations. The reasons for spermatogenic failure are various. An interruption of germ cell differentiation, spermatogenic arrest, can lead to infertility. The incidence of azoospermia was investigated in the 1996 2005 survey of Finnish AI and farm breeding boars. We focused on the diagnosis, testicular morphometry and the possible reasons for the condition. The incidence of azoospermia was significantly higher in Yorkshire boars than in the Landrace breed. The most common diagnosis in Yorkshire boars was germ cell arrest at the primary spermatocyte level. The second most frequent diagnosis in Yorkshire boars was segmental aplasia of the Wolffian ducts with idiopathic epididymal obstruction. Other reasons for azoospermia were infrequent. In the second study we investigated the incidence of two relatively well-defined specific sperm defects in Finnish Yorkshire and Landrace boars during the same survey, the immotile short-tail sperm (ISTS) defect and the knobbed acrosome (KA) defect. In the Finnish Yorkshire boars the inherited ISTS defect, and the probably inherited KA defect, were important causes of infertility during 1996 2005. The ISTS defect was found in 7.6% and the KA defect in 0.8% of the Yorkshire boars. No Landrace boars were diagnosed with either of these two defects. In the third study we described a new sterilizing sperm defect in an oligoasthenoterazoospermic bull. Because of its morphological characteristics this defect was termed the multinuclear-multiflagellar sperm (MNMFS) defect. The number of Sertoli cells in the seminiferous tubuli was highly increased in the MNMFS bull compared with the number in normal bulls. In the following two studies we used a combined approach of fluorescence in situ hybridization (FISH), flow cytometry and morphometric studies to provide information on the cytogenetic background of macrocephalic bull spermatozoa. We described cellular features of diploid spermatozoa and compared the failures in the first and second meiotic divisions. In the last study we describe how the transplantation of testicular cells was used to determine whether spermatogonia derived from donor animals are able to colonize and produce motile spermatozoa in immune-competent unrelated boars suffering the ISTS defect. Transplantation resulted in complete focal spermatogenesis, indicated by the appearance of motile spermatozoa and confirmed by genotyping.