Segregation of chromosomes in sperm of Robertsonian translocation carriers

Robertsonian translocations are the most frequent structural chromosomal abnormalities in humans and can affect fertility, with various degrees of sperm alterations in men; or the pregnancy outcome of the carriers. The studies on meiotic segregation of chromosomes in sperm of Robertsonian translocation males find a majority of normal or balanced spermatozoa for the chromosomes related to the translocation (mean 85.42%; range 60-96.60%). Furthermore, recent studies suggest an interchromosomal effect. Studies on spermatozoa from translocation carriers, and in mouse models help the comprehension of the meiotic segregation mechanisms. Results of meiotic segregation analysis in man could be integrated in genetic counselling especially when assisted reproductive technology is required.

Risk of cytomegalovirus transmission by cryopreserved semen: a study of 635 semen samples from 231 donors

BACKGROUND

The hypothetical responsibility of sperm donation in cytomegalovirus (CMV) transmission to recipients and precautions to prevent this transmission are widely discussed. The aim of this French CECOS Federation study was to evaluate both the reality and the importance of the CMV risk due to donor sperm and the relevance of measures used to screen it.

METHODS

We conducted a prospective multicentric study. CMV was detected by rapid and conventional cultures and by PCR in the frozen sperm of donors who met the normal criteria required of semen donors, irrespective of their CMV serological status.

RESULTS

635 samples from 231 donors (39.4% IgG(+)) were obtained and tested by culture; 551 samples from 197 donors were also tested by PCR. From those samples, 0.78% were culture(+), 1.57% culture(+) and/or PCR(+); 3.3% of seropositive donors and 0.72% of initially seronegative donors were culture(+), but in the latter seroconversion occurred during the quarantine period; of the 197 PCR-tested donors, 3.5% (6.2/1.7) were PCR(+), 3.3% (5.3/1.45) culture(+) and/or PCR(+). PCR(+) samples can be culture(-) and vice versa. The most strongly positive sample corresponded to an initially seronegative donor.

CONCLUSION

The best strategy to prevent potential CMV risk is to test donors for CMV IgG and IgM antibody at the outset and after a 6 month period of quarantine and to reject initially IgM seropositive donors or donors who seroconvert during the quarantine period.

AZFa deletions in Sertoli cell-only syndrome: a retrospective study

Lack of data on the genotype-phenotype relationship in cases of AZF microdeletions is due to the limited number of histological investigations in human male infertility cases. We investigated the possibility of retrospective detection of Yq11 microdeletions by using DNA extracted from diagnostic testicular biopsies. We used histological criteria to select two series of material: 22 biopsies with Sertoli cell-only syndrome and 14 biopsies with maturation arrest at the spermatocyte I stage. Two markers, DFFRY and DAZ, were tested by nested polymerase chain reaction (PCR) in the two series. In the Sertoli cell-only syndrome series, we found four deletions affecting the DFFRY gene (18.2%). In the second series, no deletions were detected. Two conclusions may be considered, although the number of specimens analysed is limited: (i) the frequency of deletions observed in Sertoli cell-only syndrome allows us to suggest that deletion in the AZFa region may be involved in this pathology; and (ii) retrospective studies may yield some additional elements in our search for eventual genotype-phenotype relationships.

Interindividual variations in the disomy frequencies of human spermatozoa and their correlation with nuclear maturity as evaluated by aniline blue staining

OBJECTIVE

To evaluate the importance of interindividual variations in the disomy frequencies of human sperm and their possible correlation with the principal semen parameters.

DESIGN

Prospective randomized analysis of sperm nuclei by fluorescence in situ hybridization and analysis of semen parameters.

SETTING

University-based laboratory for reproductive biology.

PATIENT(S)

Fifty-seven human ejaculates selected at random from a population of men undergoing semen analysis.

INTERVENTION(S)

Semen specimens were analyzed, and sperm samples were prepared for fluorescence in situ hybridization.

MAIN OUTCOME MEASURE(S)

Semen parameters, including necrozoospermia, global motility, sperm concentration, multiple abnormalities index, and teratozoospermia were evaluated, aniline blue staining was completed, and disomy frequencies for chromosomes 8, 15, 18, X, and Y were determined using fluorescence in situ hybridization.

RESULT(S)

Noticeable differences in disomy frequencies between individuals were observed, and these frequencies were correlated with the degree of nuclear maturity.

CONCLUSION(S)

We hypothesize that the positive correlation can be explained by an abnormality of chromosomal segregation at the time of meiosis that would cause disturbances during the transition of nucleoprotein or by one or several premeiotic abnormalities of chromatin that would perturb both the meiotic process and the construction of definitive proteins.

Estimation of aneuploidy levels for 8, 15, 18, X and Y chromosomes in 97 human sperm samples using fluorescence in situ hybridization

OBJECTIVE

To estimate the mean frequency of aneuploidy levels of chromosomes 8, 15, 18, X, and Y in human sperm, while minimizing the effect of individual factors by analyzing sperm samples from a large set of patients.

DESIGN

Prospective randomized analysis of sperm nuclei by fluorescence in situ hybridization.

SETTING

University-based laboratory for reproductive biology.

PATIENT(S)

One hundred two patients with a large distribution of sperm parameters, randomly selected from volunteers who had presented seeking a semen analysis.

INTERVENTION(S)

The sperm samples were prepared for fluorescence in situ hybridization.

MAIN OUTCOME MEASURE(S)

The disomy frequencies for chromosomes 8, 15, 18, and sex chromosomes were determined using fluorescence in situ hybridization.

RESULT(S)

The mean frequencies of disomy for autosomes were 0.18% for chromosome 8, 0.06% for chromosome 15, 0.2% for chromosome 18, and 0.24% for gonosomes (XX, 0.04%; YY, 0.05%; XY, 0.15%).

CONCLUSION(S)

This study confirms other previous evaluations on restricted numbers of patients. Our results seem to confirm a relative equiprobability of disomy frequencies concerning the different chromosomal pairs during male meiosis.

Analysis of the sex chromosomal equipment in spermatozoa of a 47,XYY male using two-colour fluorescence in-situ hybridization

The sex chromosomes in spermatozoa of a 47,XYY fertile male were analysed simultaneously by dual fluorescence in-situ hybridization (FISH), with two probes (pHY2.1 and pXBR). Of the 100000 cells analysed, 95179 spermatozoa (95.18%) exhibited one or more hybridization signals. Of the hybridized nuclei, 85.37% showed a normal sex chromosome constitution (37.37% X-bearing cells and 48.00% Y-bearing cells), with an X:Y ratio of 0.78:1. A total of 14.63% of the hybridized nuclei exhibited sex chromosome aneuploidy with a majority of XY- and YY-bearing spermatozoa (9.37 and 4.65% respectively). Even if the majority of spermatozoa have chromosomal haploidy, a large proportion of them exhibits numerical errors for the sex chromosomes. These observations raise questions about the commonly-admitted notions concerning the absence of chromosomal risk for XYY male offspring.

Morphometric parameters of living human in-vitro fertilization embryos; importance of the asynchronous division process

A total of 304 human pronuclear zygotes and cleaved embryos from the 2- to 9-cell stages, obtained during invitro fertilization attempts, were photographed and retrospectively analysed after transfer for their morphology and size in relation to their developmental stage, using the Imagenia programme of a Biocom 500 image analyser. Morphometric parameters were calculated from the perimeters, surface measurements, theoretical diameters and circularity factors for the different structures analysed. This report provides the morphometric characteristics of living embryos. For the whole population the mean values were: 157.4 microns for the external zona pellucida diameter, 121.8 microns for the internal zona pellucida diameter, 17.9 microns for the thickness of the zona pellucida and 117.2 microns for the embryo cell mass diameter. The morphometric characteristics of the pronuclear-stage population were significantly different from the cleaved cell stages. If the zona pellucida and cell mass embryo diameters increased slowly from the 2- to 9-cell stages, embryonic external diameters were higher and zona pellucida thicknesses were lower in odd than even number blastomere embryos. Preliminary results show that in cases where implantation occurs, the embryo has a lower zona pellucida thickness. A comparison of the different embryo cell stages confirmed the existence of an asynchronous division process during early embryo development. Global results show no evidence of morphometric differences between subpopulations of the embryos according to their microscopic grading. Deviations from the normal asynchronous division process, however, appear to be a new parameter to take into account during embryo scoring.(ABSTRACT TRUNCATED AT 250 WORDS)

Early detection of secretogranin-II (SgII) in the human fetal pituitary: immunocytochemical study using an antiserum raised against a human recombinant SgII

Secretogranin-II (SgII) is a protein contained within secretory granules of mainly gonadotrophs. The purpose of this study was to determine whether SgII immunoreactivity (SgII-IR) in the human fetal pituitary was temporally related to gonadotropin immunoreactivity. A specific antihuman SgII antiserum was thus required. A complementary DNA clone with an open reading frame for human (h) SgII was synthesized by reverse transcription-polymerase chain reaction from pituitary total RNA. This clone was used to obtain the SgII polypeptide (-9 to 152) as a fusion protein, in a heterologous expression prokaryotic system. Antisera against the fusion protein were raised in rabbits and checked for specificity and sensitivity through Western blotting. Human fetal pituitaries from week 6 of gestation onward were used for immunocytochemical studies. Consecutive semithin sections were treated with the specific antisera against hSgII, beta-endorphin, and hPRL and with monoclonal antibodies to hCG alpha, hLH, and hFSH. SgII immunoreactivity appeared at week 8 and was restricted to pituitary cells expressing beta-endorphin (100% colocalization). At week 9, FSH-positive cells did not contain SgII. From week 10, gonadotrophs progressively exhibited SgII-IR, up to 50% of that in FSH-containing cells at week 26. The granin was never found in PRL cells whatever the stage of development. The present data demonstrate that SgII-IR is detected very early in fetal life; however, the positive cells are not gonadotrophs, but corticotrophs. Within gonadotrophs, SgII appears subsequent to hormones. At birth, more than 90% of SgII-IR cells are represented by corticotrophs and gonadotrophs.

Human hypothalamic neuronal system revealed with a salmon melanin-concentrating hormone (MCH) antiserum

An antiserum raised against synthetic salmon melanin-concentrating hormone (MCH) reveals an extensive neuronal system in the posterior lateral areas of the human hypothalamus. These neurons correspond to those previously described in the rat, which are characterized by expression of MCH-like, alpha-melanotropin-like and human growth hormone-releasing factor (1-37)-like immunoreactivities.

Human corticoliberin hypothalamic neuroglandular system: comparative immunocytochemical study with anti-rat and anti-ovine corticotropin-releasing factor sera in the early stages of development

Development of the paraventriculo-infundibular corticoliberin system was studied by immunocytochemical analysis of human hypothalamic sections using antisera raised against rat or ovine corticotropin-releasing factor (CRF). This comparative study confirms the presence of a significant number of CRF-immunoreactive fibers in the median eminence during the 16th week of fetal development and suggests they may appear as early as the 14th week. Some hypothalamic peri- and paraventricular neurons, observed from the 12th week, are rat-CRF-immunoreactive but not ovine CRF-immunoreactive. There appears to be chronological differences concerning the ability of the two antisera to recognize hypothalamic structures during the early stage of development.

Anatomical and ontogenetic studies of the human paraventriculo-infundibular corticoliberin system

In human fetus, newborn, infant and adult hypothalami, antibodies to ovine corticoliberin-41 stain a paraventriculo-infundibular neuroglandular pathway. The perikarya are located in the paraventricular nucleus, they mainly project to the ventral and lateral areas of the median eminence. Eminential corticoliberin-positive fibres appear during the 16th week of fetal life, and increase in number during the following weeks. Perikarya were first revealed in the 19th week. In some areas of the median eminence, corticoliberin-, vasopressin- or [Met]enkephalin-immunoreactive terminals are similarly distributed. Sequential stainings or staining comparison of contiguous semi-thin sections failed to prove the coexpression of corticoliberin and [Met]enkephalin immunoreactivities in fibres, but indicated that corticoliberin and vasopressin immunoreactivities may be coexpressed in a few fibres. Those methods enabled us to observe, in the paraventricular nucleus, perikarya revealed by corticoliberin and vasopressin antisera. Our results suggest a possible release of corticoliberin in portal vessels of the median eminence beginning in the 16th week of fetal life, i.e. 8 weeks later than appearance of the corticotrophs in the pituitary. Establishment of a corticoliberin hypothalamic control of pituitary corticotrophs at mid gestation agrees with previous physiological and teratological studies. Abundance, as well as immunostaining intensity of the corticoliberin processes, in the infant and adult median eminence attest to the physiological importance of this system. Close vicinity of corticoliberin, vasopressin and [Met]enkephalin fibres, in some eminential areas and coexpression of corticoliberin and vasopressin immunoreactivities in some neurons, are morphological correlates of functional relations which were reported.

Ontogeny of the neuroglandular system revealed with HPGRF 44 antibodies in human hypothalamus

Using the indirect immunofluorescence technique, an antiserum to synthetic hpGRF 44 (the 44 residue peptide with high growth hormone releasing activity isolated from a human pancreatic tumor), antibodies of which interact with 40-44 C terminal amino acid sequence, stains a novel neuron system in the adult human hypothalamus. HpGRF-like immunoreactivity (GLI) containing neurons are different from previously known peptidergic systems. GLI perikarya are few in number and located mainly in the infundibular nucleus. In the median eminence, abundant GLI fibers terminate against portal capillaries in the same areas as somatostatin fibers which are morphologically different. No GLI staining was observed in hypothalami before 18 weeks of fetal development. GLI perikarya and intraeminential nerve terminals were simultaneously detected in 18-week-old fetuses attesting to a possible release of this peptide in the portal vessels as early as this stage. GLI neuron system was steadily revealed in 19- to 30-week-old fetuses. It was not detectable in 6 out of the 7 studied hypothalami from newborn infants. In most infant and adult hypothalami, it is well developed. Results presented here support the hypothesis (1) that hpGRF antiserum stains the neuron system producing the somatocrinin and (2) that this neuron system may begin in controlling pituitary somatotrophs at the 18th week of fetal development, which is in agreement with previous hypotheses.

Corticoliberin neurons: cytophysiology, phylogeny and ontogeny

In the rat hypothalamus, antibodies to ovine CRF41 stain neurons of a paraventriculo-infundibular neuroglandular pathway. CRF like immunoreactivity (CLI)-containing perikarya are mostly packed in the parvocellular division of the paraventricular nucleus. Their morphology and topography differ from that of other peptidergic neurons. However a few CLI perikarya are also stained with vasopressin antibodies. CLI neurons project massively to the external layer of the median eminence (ELME). Adrenalectomy induced a total depletion of ELME CLI 12 to 24 h after surgery, followed by a secondary accumulation already conspicuous 5 days later. This biphasic evolution, identical to that of ELME vasopressin, is totally prevented by a replacement therapy with dexamethasone. Reserpine also induces an acute depletion of ELME CLI and vasopressin, that can be prevented by a monoamine oxidase inhibitor pretreatment. These results indicate the involvement of CLI neurons in the corticotropic axis, suggesting that they are indeed corticoliberin neurons. Among the extrahypothalamic locations of CLI neurons their abundance in the amygdala central nucleus is of interest since it is involved in the corticotropic axis. A similar pattern of CLI was noticed in several mammalian brains and also in lower vertebrates (birds, reptiles, amphibians, fishes). Species adaptations of CLI neurons were observed: CLI neurons are of the cerebrospinal fluid contacting type in the turtle. CLI fibres terminate close to corticotrophs in the fish pituitary. This suggests a direct excitosecretory role of CRF on these cells and concurs with a CRF function of CLI peptide even in fishes. CLI processes and terminals appear in the human fetal ELME at the 16th week of development and increase in number during the following weeks. Perikarya are seen at 19 weeks. In the rat CLI fibers and perikarya were detected as early as the 18th day of fetal development. Thus, paraventriculo-infundibular CLI system develops later than corticotrophs. This chronology perfectly concurs with the results of previous physiological and experimental studies.

The CRF neuron: immunocytochemical study

In the central nervous systems of several species belonging to different vertebrate classes, immunocytochemical stainings with an antiserum to ovine CRF 41 show multiple location of CRF perikarya and various areas containing CRF fibres and terminals. These stainings reflect species and interspecies functional adaptations of the CRF neurones which constitute a prominent hypothalamo-infundibular system involved in pituitary gland control, and also interneurone systems as attested to by extrahypothalamic perikarya and by CRF perisomatal endings in several brain areas. Perikarya of the hypothalamo-infundibular system are mainly packed in the paraventricular nucleus (mammals, birds) or in homologous areas, e.g.: paraventricular organ (turtle) where they are CSF-contacting neurones and preoptic nucleus (amphibians, fishes). In all species but fish, CRF fibres end in the median eminence (ME) against portal vessels. In fish, CRF processes terminate in the peripheral areas of proadenohypophyseal neurodigitations, close to corticotrophs. In all species these stainings are abolished by preabsorption of the serum by CRF. In fishes, reptiles and amphibians they are also suppressed by urotensin I, which is thought to be the teleost's CRF. Adrenalectomy experiments in the rat provided evidence for a corticosteroid regulation of ME CRF: short term (12-24 hr) adrenalectomy induces a complete depletion of CRF immunoreactivity followed by a secondary accumulation (5-20 days). This biphasic evolution is prevented by a dexamethasone replacement therapy. Inhibitory role of catecholamines on CRF release was indicated by: disappearance of ME CRF, induced by a single reserpine injection and suppression of this effect by monoamineoxidase inhibitor (pargyline or tranylcypromine) pretreatment. CRF fibres were first observed in the ME at the 16th week of fetal development in the human, and at the 18th day in the rat fetus. Thus, immunoreactive CRF system develops later than pituitary corticotrophs.

Immunocytochemical demonstration of a novel peptidergic neurone system in the cat brain with an anti-growth hormone-releasing factor serum

In 15-day-, 1-month- and 1.5-month- old cats an antiserum against hpGRF-44 stained a novel hypothalamo-infundibular neuroglandular system. Its intra-eminential processes present an important development between 15 and 30 days of age. Perikarya and nerve fibres, which are abundant in several brain areas as early as the 15th day, suggest that the peptide revealed by hpGRF-44 antibodies also acts as a neuromodulator.

Quantitative immunocytochemical studies on the gonadotrophs isolated from the pituitary of the male rat

Quantitative studies on the population of the gonadotropic cells in the pituitary of adult male rats were performed after trypsic dissociation of the pituitary glands and immunoenzymatic staining with anti-beta-LH or anti-beta-FSH antisera. Number, area and extinction of labelled cells were measured by use of an image analyser and a cytophotometer. The gonadotrophs represent approximately 14% of the pituitary cells. The mean area of gonadotrophs is significantly larger after staining with anti-beta-LH serum than after staining with anti-beta-FSH serum. Planimetric measurement of the gonadotrophs reveals their variability in size ranging between 30 and 160 microns2. Moreover, the size distribution depends on the staining serum used: more numerous small-sized cells (less than 75 microns2) are stained with anti-beta-FSH serum than with anti-beta-LH serum, which conversely stains more numerous large-sized cells. Cytophotometric measurements indicate that immunostaining varies greatly among cells of the same size class and that the staining intensity appears to increase according to the cell size. These results emphasize the morphofunctional heterogeneity of the gonadotropic cell population.

[Immunocytochemical study of the ontogenesis of the CRF-containing neuroglandular system in the human hypothalamus (author's transl)]

In the human fetus, the first anti CRF-stained fibres appear in the median eminence during the 16th week. From the 17th week, they are more numerous and they establish neurohemal terminals close to the superficial capillaries and around some of the developing intra-eminential vascular loops. In new born infants infundibular CRF-containing processes and terminals are strongly immunoreactive and very few CRF-containing perikarya can be detected in the paraventricular nucleus.