Silver-stained accessory structures on human sex chromosomes

The Eutherian Pseudoautosomal Region

The pseudoautosomal region (PAR) is a unique segment of sequence homology between differentiated sex chromosomes where recombination occurs during meiosis. Molecular and functional properties of the PAR are distinctive from the autosomes and the remaining regions of the sex chromosomes. These include a higher rate of recombination than genome average, bias towards GC-substitutions and increased interindividual nucleotide divergence and mutations. As yet, the PAR has been physically demarcated in only 28 eutherian species representing 6 mammalian orders. Murid rodents have the smallest, gene-poorest and most diverged PARs. Other eutherian PARs are largely homologous but differ in size and gene content, being the smallest in equids and human/simian primates and much larger in other eutherians. Because pseudoautosomal genes escape X inactivation, their dosage changes with sex chromosome aneuploidies, whereas phenotypic effects of the latter depend on the size and gene content of the PAR. Thus, X monosomy is more viable in mice, humans and horses than in species with larger PARs. Presently, little is known about the functions of PAR genes in individual species, though human studies suggest their involvement in early embryonic development. The PAR is, thus, of evolutionary, genetic and biomedical significance and a 'research hotspot' in eutherian genomes.

Sex Chromosome Alignment at Meiosis of Azoospermic Men With Azoospermia Factor Microdeletion

Deletions in the q arm of the Y chromosome result in spermatogenesis impairment. The aim of the present study was to observe the X and Y chromosome alignment in the spermatocytes of men with Y chromosome microdeletion of the azoospermia factor (AZF) region. This was performed by multicolor fluorescence in situ hybridization probes for the centromere and telomere regions. Testicular biopsies were performed in a testicular sperm extraction-intracytoplasmic sperm injection set-up in 11 azoospermic men: 8 (nonobstructive) with AZF deletions and 3 (obstructive) controls. Histological sections, cytology preparations of the testicular biopsies, and evaluation of the meiosis according to the percentage of XY and 18 bivalents formation were assessed. Spermatozoa were identified in at least one location in controls and specimens with AZFc-deleted Y chromosomes. Complete spermatocyte arrest was found in those with a deletion that included the entire AZFb region. Bivalent formation rate of chromosome 18 was high in all samples (81%-99%). In contrast, the rate of bivalent X-Y as determined by centromeric probes was lower but in the range favorable with spermatozoa findings in controls and patients with the AZFc deletion (56%-90%), but not in those with AZFb-c deletions (28%-29%). A dramatic impairment in the normal alignment of X and Y telomeres in the specimen with AZFb-c deletion was shown (29%), compared to the specimens with AZFc deletion (70%-94%). It is suggested that the absence of sperm cells in specimens with the entire AZFb and with AZFb-c deletions is accompanied by meiosis impairment, perhaps as a result of the extent of the deletion or because of the absence of genes that are involved in the X and Y chromosome alignment.

The pseudoautosomal region and sex chromosome aneuploidies in domestic species

The pseudoautosomal region (PAR) is a unique and specialized segment on the mammalian sex chromosomes with known functions in male meiosis and fertility. Detailed molecular studies of the region in human and mouse show dramatic differences between the 2 PARs. Recent mapping efforts in horse, dog/cat, cattle/ruminants, pig and alpaca indicate that the PAR also varies in size and gene content between other species. Given that PAR genes escape X inactivation, these differences might critically affect the genetic consequences, such as embryonic survival and postnatal phenotypes of sex chromosome aneuploidies. The aim of this review is to combine the available information about the organization of the PAR in domestic species with the cytogenetic data on sex chromosome aneuploidies. We show that viable XO individuals are relatively frequently found in species with small PARs, such as horses, humans and mice but are rare or absent in species in which the PAR is substantially larger, like in cattle/ruminants, dogs, pigs, and alpacas. No similar correlation can be detected between the PAR size and the X chromosome trisomy in different species. Recent evidence about the likely involvement of PAR genes in placenta formation, early embryonic development and genomic imprinting are presented.

Proximal vs. distal collochores in Coleopteran chromosomes

One important mechanical requirement of meiotic chromosomes is to maintain sister chromatids in contact until the onset of anaphase-2. Monocentric chromosomes normally achieve this by means of specialized pericentric regions. However, in some cases the sites of the last chromatid contact can be shifted from such regions to the distal tips of the chromatids, or even to interstitial segments. It is proposed that all three variants, documented by observations in male meiosis of certain flea beetles, can be accommodated by the common term collochore.

The synaptonemal complex and meiotic recombination in humans: new approaches to old questions

Meiotic prophase serves as an arena for the interplay of two important cellular activities, meiotic recombination and synapsis of homologous chromosomes. Synapsis is mediated by the synaptonemal complex (SC), originally characterized as a structure linked to pairing of meiotic chromosomes (Moses (1958) J Biophys Biochem Cytol 4:633-638). In 1975, the first electron micrographs of human pachytene stage SCs were presented (Moses et al. (1975) Science 187:363-365) and over the next 15 years the importance of the SC to normal meiotic progression in human males and females was established (Jhanwar and Chaganti (1980) Hum Genet 54:405-408; Pathak and Elder (1980) Hum Genet 54:171-175; Solari (1980) Chromosoma 81:315-337; Speed (1984) Hum Genet 66:176-180; Wallace and Hulten (1985) Ann Hum Genet 49(Pt 3):215-226). Further, these studies made it clear that abnormalities in the assembly or maintenance of the SC were an important contributor to human infertility (Chaganti et al. (1980) Am J Hum Genet 32:833-848; Vidal et al. (1982) Hum Genet 60:301-304; Bojko (1983) Carlsberg Res Commun 48:285-305; Bojko (1985) Carlsberg Res Commun 50:43-72; Templado et al. (1984) Hum Genet 67:162-165; Navarro et al. (1986) Hum Reprod 1:523-527; Garcia et al. (1989) Hum Genet 2:147-53). However, the utility of these early studies was limited by lack of information on the structural composition of the SC and the identity of other SC-associated proteins. Fortunately, studies of the past 15 years have gone a long way toward remedying this problem. In this minireview, we highlight the most important of these advances as they pertain to human meiosis, focusing on temporal aspects of SC assembly, the relationship between the SC and meiotic recombination, and the contribution of SC abnormalities to human infertility.

Combined administration of low-dose gossypol acetic acid with desogestrel/mini-dose ethinylestradiol/testosterone undecanoate as an oral contraceptive for men

To evaluate the efficacy and feasibility of a new regimen of low-dose gossypol acetic acid (GA) combined with desogestrel/ethinylestradiol and testosterone undecanoate (DSG/E/TU) as a male contraceptive, adult male rats were fed orally with GA (12.5 mg/kg/day) and DSG (0.125 mg/kg)/E (0.025 mg/kg)/TU (100 mg/kg) daily for 8 weeks as loading dose until infertility, and a similar low dose of GA alone for infertility maintenance. Control animals were administered a single low dose of GA (12.5 mg/kg/day) or DSG (0.125 mg/kg)/E (0.025 mg/kg)/TU (100 mg/kg), and vehicle, respectively. Results demonstrated that the combined dosage regimen could damage epididymal sperm motility and density, and induce infertility within 8 weeks in rats; the infertility could be consistently sustained by giving single GA (12.5 mg/kg/day), and was reversible in about 8 weeks following withdrawal of gossypol. The regimen rendered treated male rats with spermiation failure within a period of 6-20 weeks of treatment. Also, the serum luteinizing hormone, follicle-stimulating hormone and testicular interstitial fluid testosterone levels showed a transient decrease at the end of 6 or 8 weeks, which returned to control levels after 8 weeks of recovery phase. No hypokalemia or other adverse effects in viscera were observed. These results provide a promising approach to using the new regimen for the development of an effective and reversible oral male contraceptive.

Pharmacological concentrations of follicle-stimulating hormone and testosterone improve the efficacy of in vitro germ cell differentiation in men with maturation arrest

OBJECTIVE

To examine whether in vitro differentiation of germ cells from men with maturation arrest is improved by augmenting FSH and T concentrations above the values effective in samples from men with normal spermatogenesis.

DESIGN

Prospective, controlled in vitro study.

SETTING

Private assisted reproduction centers and a university department.

PATIENT(S)

Men with meiotic or postmeiotic maturation arrest.

INTERVENTION(S)

Testicular spermatid extraction, in vitro culture of testicular biopsy samples, intraoocyte injection of elongated spermatids, embryo culture and transfer.

MAIN OUTCOME MEASURE(S)

Progression of in vitro germ cell differentiation, fertilization, and pregnancy outcomes with in vitro cultured germ cells.

RESULT(S)

In some cases of meiotic and postmeiotic maturation arrest, more advanced germ cell stages were achieved by in vitro culture in the presence of 500 IU/L FSH as compared with 50 IU/L FSH. The beneficial effect of 500 IU/L FSH was further potentiated by a simultaneous increase of T concentration from 1 to 10 microM. Fertilizations with germ cells recovered after incubation with these pharmacological hormone concentrations gave rise to viable embryos and the births of five healthy babies.

CONCLUSION(S)

Pharmacological concentrations of FSH and T are beneficial for in vitro maturation of germ cells from some men with in vivo maturation arrest.

Cytoplasmic events in human meiotic arrest as revealed by immunolabelling of spermatocyte proacrosin

Proacrosin appears in the Golgi complex as early as the mid-pachytene stage and immediately thereafter initiates partition to be equally distributed in spermatids. The anti-proacrosin monoclonal antibody 4D4 (mAb 4D4) was used as a marker of these cytoplasmic events in ten men exhibiting spermatogenesis arrest in three specific stages: (i) leptotene/zygotene spermatocyte I with impaired chromosome pairing (six cases), (ii) early pachytene I (one case) and (iii) metaphase/anaphase I (three cases). Prophase arrest stages were identified on testis sections stained by silver nitrate. MAb 4D4 labelling revealed two types of leptotene/zygotene arrest depending on whether proacrosin was expressed or not. The data obtained enabled us to distinguish between: (i) nuclear blockages due to chromosome and/or nuclear matrix anomalies, when cytoplasmic events were either inhibited or not inhibited, and (ii) nuclear anomalies due to microtubular disturbances. In this latter case, cytokinesis was impaired as early as the prophase I, thus indicating a relationship between the Golgi partitioning and the microtubule network. Data show that meiotic arrest investigations, by means of an appropriate marker of the cytoplasmic events, provide valuable information on spermatogenic developmental processes.

Expression of the X–inactivation–associated gene XIST during spermatogenesis

Mammalian X-chromosome inactivation is thought to be controlled by the X inactivation centre (XIC, X-controlling element -Xce-in mice). A human gene, XIST and its mouse counterpart, Xist, which map to the XIC/Xce, are expressed exclusively from inactive X chromosomes, suggesting their involvement in the process of X-inactivation. We now report the presence of Xist/XIST transcripts in newborn and adult mouse testes, and in human testicular tissue with normal spermatogenesis, but not in the testes of patients who lack germ cells. Our results indicate that while the X chromosome in males is active in somatic cells, it undergoes inactivation during spermatogenesis.

Computer-assisted image analysis of silver staining in normal and leukemic bone marrow

Computer-assisted image analysis was used to quantitate the amount of silver staining in interphase nuclei of bone marrow cells from acute lymphocytic leukemia (ALL) patients. When we compared the data obtained for the interphase nuclei with that obtained for the metaphase spreads, we found a strong correlation between the fraction of bone-marrow metaphases stained positively with silver, the average number of silver-positive nucleolus organizer regions per metaphase, and the amount of silver staining in the interphase nuclei. Computer-assisted image analysis of interphase nuclei can be used, therefore, to differentiate normal from ALL bone-marrow samples.

Differential nucleolus organizer activity in normal and leukemic bone marrow

A cytochemical technique that uses silver nitrate staining has been used to study the nucleolus organizer activity in bone marrow cells from 13 patients with acute lymphocytic leukemia (ALL), 11 patients with chronic myelogenous leukemia (CML), 7 patients with acute myelogenous leukemia (AML), and 4 healthy persons. Our results indicate that the nucleolus organizer region (NOR) activity was significantly lower in the control group than in the ALL patients. The NOR activity level was significantly lower in both the CML patients in chronic phase and the AML patients than in the ALL group and similar to the control group. These disease-related differences in NOR activity as detected by silver staining can be used as diagnostic procedure in evaluating human leukemias.

Differential silver-positive nucleolus organizer region activity in normal and malignant murine tissues

Transcriptionally active nucleolus organizer regions (NORs) were analyzed using a silver-staining technique. The levels of silver-positive NOR activity for normal murine bone marrow and thymus cells were established, and significant differences in ribosomal RNA gene activity were observed. When tumor cells originating from these two tissue types were also studied, significant differences were seen not only between the normal and malignant tissues, but between the two tumor types as well. These differences in ribosomal RNA gene activity with respect to cell type and malignancy may be useful diagnostically.

Cytogenetic studies on Cervus elaphus. II. Synaptonemal complexes and NOR activity during spermatogenesis

The activity of the nucleolus organizer regions (NORs) in various stages of spermatogenesis of the red deer was studied with the silver staining technique. The Ag-stainability of the NORs, an indicator of the transcriptional activity of the r-RNA genes, is present during the meiotic prophase until pachytene and is absent during the remainder of the meiotic prophase, to reappear during the first stages of spermiogenesis and then disappear again during the elongation phase of the spermatids. The development and behaviour of synaptonemal complexes (SCs) of primary spermatocytes were also studied with the silver staining technique under the light microscope. The organization of SC is similar to that of other mammalian species. The pairing behaviour of the axes of the sex chromosomes is described.

Methods for chromosome banding of human and experimental tumors in vitro

Technological advances in the study of chromosomes from human and experimental cancers are occurring rapidly. Molecular cytogenetic techniques for in situ hybridization, as well as chromosome sorting and even karyotyping via flow cytometry (both described elsewhere within this volume), are important developing areas receiving considerable study. However, there currently remains a significant need for routine karyotyping of mammalian cells. It is hoped that the methods provided in this chapter will be of help in assisting somatic cell geneticists to identify chromosome changes in mammalian cell cultures.

Cytogenetic analysis in human breast carcinoma. II. Seven cases in the triploid/tetraploid range investigated using direct preparations

This report presents karyotypes of seven breast carcinomas with high ploidy from our total of 111 cases. These karyotypes were highly complex and there was no indication of a specific deletion of 16p12----pter as indicated by the previous analysis of some near-diploid tumors. A comparison of numerical changes did not demonstrate a common loss of chromosome #16 as in the near-diploid tumors, but an equivalent loss of chromosomes #8 and #13 was found.

EM investigations of surface spread synaptonemal complexes in a human male carrier of a pericentric inversion inv(13)(p12q14): the role of heterosynapsis for spermatocyte survival

EM investigations of surface spread synaptonemal complexes of pachytene spermatocytes were performed on a human male carrier of a pericentric inv(13), ascertained through his daughter with a duplication-deficiency of the same chromosome. The inv(13) bivalent could be unambiguously identified by either its asymmetrical kinetochores or its nucleolar association or both. There was scarcity of reversed homosynapsis of the inverted segments with inversion loops, possibly related to the small size of the inversion. The majority of pachytene spermatocytes showed the inverted segment to be either asynapsed or heterosynapsed. Generally initial homosynapsis is highly efficient with high fidelity, while heterosynapsis at the secondary pachytene pairing phase may take place with any available partner remaining unsynapsed and including the differential segments of the XY. It is suggested that survival of spermatocytes to later stages of meiosis may be ensured by heterosynapsis, and the recombinant chromosome in the offspring might be the result of a U-type exchange.

Methodologic advances in the cytogenetic analysis of human solid tumors

The major obstacle to successful cytogenetic analysis of human solid tumors is the acquisition of sufficient numbers of good quality metaphases for detailed cytogenetic analysis. At present, no single methodologic approach has been proven to provide successful chromosomal analysis of all human solid tumors. The technical aspects of cell culture, chromosome harvesting, and chromosome banding were the focus of considerable discussion during the First Workshop on Chromosomes in Solid Tumors. This report provides summaries of several technical protocols, emanating from several different laboratories, which have contributed to successful chromosome analysis of a variety of human solid tumors.

Ag-NOR staining in human chromosomes: differential staining in normal and leukemic bone-marrow samples

A silver staining technique developed by Goodpasture and Bloom (1975) stains a specific protein associated with the activity of ribosomal cistrons during the preceding interphase. By counting the number of chromosomes with darkly stained nucleolus organizer regions (NORs), the number of active NORs per metaphase can be determined. A comparison of NOR activity in bone-marrow cells from leukemic patients in different stages of disease with that of bone marrow from normal, healthy individuals was conducted and differential NOR activity was detected. The control group showed significantly lower NOR activity when compared with a group of patients with acute lymphocytic leukemia (ALL). These preliminary data indicate that this simple cytochemical technique can be effectively used to differentiate between normal and ALL bone-marrow samples.

A complex three breakpoint translocation involving chromosomes 2, 4, and 9 identified by meiotic investigations of a human male ascertained for subfertility

Whole mount pachytene spreads were used to investigate the pairing of a supposed balanced reciprocal t(4;9) translocation in a human male ascertained for subfertility. All well spread pachytene spermatocytes analysed by light microscopy and electron microscopy contained a hexavalent instead of the expected quadrivalent this suggesting that a third chromosome was involved. The hexavalent showed a high efficiency of synapsis with the six arms fully paired except for the proximal segments adjacent to the breakpoints. Further meiotic investigations by the air-drying technique and the reassessment of the mitotic karyotype using stretched chromosomes revealed that the rearrangement is indeed a complex three breakpoint translocation t(2;4;9)(p13;q25;p12). There was an indication of a reduced chiasma frequency of the hexavalent but no interchromosomal effect on chiasma pattern could be detected. No selective association between the hexavalent and the XY configuration was found at any stage, and unless the central lack of pairing is of relevance we have no explanation for the subfertility and reduced testicular size. Except for the hexavalent the most impressive feature of the meiosis of this complex translocation was in fact its normality including the end product with repeated spermiograms being indistinguishable from the normal. Karyotyping of individual spermatozoa has, however, not been performed.

Distinct argyrophilic cytoplasmic organelles revealed during mouse spermiogenesis. A fine structural and cytochemical study

An electron microscopic Ag-staining method was used to study the argyrophilia of specific cytoplasmic organelles that appear during mouse spermiogenesis. The microtubuli of the centrioles are surrounded by a thin layer of argyrophilic material that also surrounds the microtubuli of their derivatives, e.g., the centriolar adjunct, the axoneme, and some structures of the connecting piece. As the mantle, i.e., the junctional complex between Sertoli cell and spermatid, develops, the involved regions of its plasma membranes are covered with silver precipitates. The apical portion of the nuclear ring as well as that of the perforatorium show clear argyrophilia. Besides these structures, a number of ring-shaped and spheroidal bodies at various sites in the cell also are decorated with silver precipitates. Most of these argyrophilic structures show a positive reaction with the EDTA method, too, suggesting that they contain ribonucleoprotein and might be of nucleolar origin. Since, furthermore, most of these structures are known to contain distinct cytoskeletal proteins, it is assumed that the staining reaction might be caused by proteins that are associated with the genuine cytoskeletal proteins.

Cytogenetic analysis in human breast carcinoma. I. Nine cases in the diploid range investigated using direct preparations

Cells in mitosis were found in 51 of 110 (47%) breast tumor samples; karyotypes of nine tumors in the diploid range are presented. The simplest stemline karyotype found was 46,XX, -16, +del(1)(qter----p21). The chromosome homologues most frequently lost were #8, #13, and #16. Monosomy or partial monosomy for chromosome #16 was seen in six cases, including the two simplest and chromosome #16 might be of relevance for initiation of malignant transformation in breast carcinoma. The only chromosome feature common to all nine breast carcinomas was the presence of a marker involving the long arm of chromosome #1, the region shared by all being 1qter----1q21.

Meiotic studies and synaptonemal complex analysis in two infertile males with a 13/14 balanced translocation

Meiotic and synaptonemal complex studies by light and electron microscopy have been carried out in two infertile males with a balanced 13/14 translocation. As expected, all metaphase I figures in conventional meiotic preparations contained a chain trivalent. Synaptonemal complex studies showed typical trivalent images with incomplete pairing of the acrocentric elements in the cis configuration. A review of the literature shows that the fertility of these patients is quite variable. All of them show a slightly reduced number of chiasmata (mean 46.6). Pairing in cis, as detected by electron microscopic studies, does not seem to have a prognostic value.

Presence of retrovirus in the B95-8 Epstein-Barr virus-producing cell line from different sources

The B95-8 cell line, a widely used source of highly transforming Epstein-Barr virus (EBV), obtained from the laboratory of origin, harbored an infectious retrovirus. This retrovirus generally resembled the Type D retroviruses structurally and developmentally and like the Type D retroviruses preferred Mg2+ to Mn2+ in its RNA-directed DNA polymerase reaction. Evidence for the presence of retrovirus was found in B95-8 cultures from two other sources within the United States, either by assay for polymerase or by electron microscopy. Comparison of two B95-8 cell lines showed cytogenetic differences as well as differences in retroviral activities. The results suggest that any B95-8 culture should be tested for the presence of retrovirus before its use as a source of EBV.

Comparative silver staining patterns of water buffalo, goat, and pig spermatozoa

Spermatozoa from river and swamp water buffalo (Bubalus bubalis), goat, and pig were stained using a silver nitrate procedure and examined under bright field optics. The silver nitrate differentiated many detailed morphologic features of the head, midpiece, and tail of spermatozoa between the species studied. Acrosomal integrity due to sperm injury or aging and various sperm abnormalities were also clearly identified by silver nitrate. Silver staining patterns revealed species-specific and strain-specific differences, particularly of the sperm head. The biochemical basis of silver staining has been attributed to the presence of sulphydryl and disulphide-rich proteins. The technique is relatively inexpensive, rapid, and repeatable and may be useful for biological research and evaluation of semen for artificial insemination.

Isolation and preliminary characterization of the synaptonemal complex from rat pachytene spermatocytes

A method for preparation of the morphologically intact synaptonemal complex from rat pachytene spermatocytes is described. Pachytene spermatocytes were fractionated from rat testicular cells by centrifugal elutriation. Nuclei from fractionated pachytene cells were prepared and extensively digested with micrococcal nuclease. The digested nuclei were sedimented through 20% (w/v) sucrose containing 2 M NaCl by centrifugation. About 10% of total nuclear proteins and 1-2% of total genomic DNA was found to be associated with the residual structure. The residual structure, which contains mainly the synaptonemal complex, but may be still contaminated with other nuclear components including membrane and matrix, was stained with silver and examined under light microscopy. It was found that a silver-staining component of the synaptonemal complex is not grossly different from that in pachytene nuclei not subjected to digestion and extraction. Sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis revealed that virtually all the proteins in the residual structure are non-histones. The DNA isolated from the residual structure was about 135 base pairs (bp), long. The DNA was end-labeled and hybridized with a large excess of sonicated rat genomic DNA. The hybridization displayed a kinetics virtually identical to that of total nuclear DNA. We also prepared restricted DNA fragments associated with the residual structure. Southern blot analyses using a probe made from a recombinant DNA clone containing the albumin gene revealed that the DNA associated with the residual structure was not enriched (or depleted) in this gene sequence. Our results strongly suggest that (1) the synaptomenal complex may play a structural role to support the chromatin domains inside pachytene nucleus; and (2) a simple common DNA sequence in the chromatin domain is not required for association with the residual structure which contains morphologically intact synaptonemal complex in rat spermatocytes.

Dense bodies in silver-stained spermatocytes of the Chinese hamster: behavior and cytochemical nature

From the silver staining behavior of various organelles in the nucleus we have divided meiotic prophase (leptotene to the diffuse stage) of the male Chinese hamster into five stages. Components within the nucleus, such as synaptonemal complex (SC), sex bivalent (SB), nucleolus organizer regions (NORs), chromatin and the dense bodies, showed a characteristic feature in each stage of meiotic prophase. The lampbrush chromosome stage was found to be followed by the diffuse stage. The chromatin around SC began to be organized at early pachytene and formed a brush-like structure at late pachytene. During early prophase stages a dramatic change in SB morphology occurred. Three types of morphology of SB were recognized: (1) the XY pair with long synapsis and fusiform or diffuse thickening of the unpaired portions (late zygotene and early pachytene), (2) desynapsed, branched, and anastomosed axes seen at late pachytene. Two types of the dense body were found during meiotic prophase; the double body in early stage (leptotene to early pachytene) and the single body in later stages (mid pachytene to diffuse stage). The small precursors of the double body existed at early leptotene but they increased in size and also changed the silver stainability during zygotene, becoming the characteristic double body consisted of one light body (L-body) and one dark body (D-body). These two bodies can also be recognized after Giemsa or acridine orange (AO) staining. The L-body fluoresced reddish orange after AO staining. The single body, which is probably formed by amalgamation of the D- and the L-bodies, showed a staining reaction similar to that of the D-body. Data from pancreatic lipase and protease treatments suggest that the D-body contained a lipoprotein.

Demonstration of kinetochores and centrioles in spermatocytes of two species of cockroaches by silver staining

Light microscopy following silver staining of spermatocytes of German and Madagascar hissing cockroaches demonstrated: (1) the localization of a kinetochore in each autosomal synaptonemal complex during pachytene, and (2) visualization of centrioles in different stages of meiotic prophase. The presence of a "hairpin-like" twist and the nucleolus organizer region in the X-chromosome was observed only in the German cockroach.

Meiotic and synaptonemal complex studies in a 14/21 translocation carrier

Meiotic studies in a sterile carrier of a 14/21 translocation showed a meiotic arrest, with degeneration of primary spermatocytes. Silver staining of pachytene cells revealed the presence of a trivalent. Its synaptonemal complex was quite similar to that described in previous light and electron microscopy studied in mammalian species. The observation of a trivalent with pairing in trans-configuration and the presence of desynaptic synaptonemal complexes in early pachytene could explain the relatively high incidence of non-disjunction in human D/G translocations and the spermatogenic disintegration sometimes seen in these cases.

Synaptonemal complex of the sex-autosome trivalent in a male indian muntjac

Bright-field microscopy of silver-stained pachytene spermatocytes of a male Indian muntjac, Muntiacus muntjak revealed that (a) the synapsis between the autosomal homologs, including the long arm of the X and Y2, was normal, (b) the nucleolus organizer regions were present in both the No. 1 bivalent and the long arm of the X and Y2, (c) the accessory structures of the X chromosome short arm in the forms of light and dark thickenings and the hairpin-like bend were present despite the X-autosome translocation, (d) a short synaptonemal complex was present between the Y1 (real Y) and the short arm of the X chromosome, and (e) the centromeric orientation of the Y1 and Y2 chromosomes was in Cis configuration as opposed to the X chromosome.

The length of silver-stained human autosomal pachytene chromosomes

The length of 44 silver-stained human autosomal pachytene complements was shown to vary from about 300 micrometer to at least 535 micrometer. The lengths of the individual 22 autosomal chromosomes of eight complements representing this interval was measured and the relative lengths calculated. For most of the chromosomes a 1:1 relationship was found between the relative length and the corresponding relative DNA content (Mendelsohn et al. 1973). For some of the chromosomes this ratio seemed to deviate systematically from the 1:1 ratio. The data indicate a different organization of certain stages of the meiotic and the mitotic chromosome (Bak et al. 1979).

Behavior of the chromosome core in mitosis and meiosis

A simple method has been described for the visualization of chromosomes cores with light microscopy in conventional chromosome preparations. The technique is relatively simple, highly reproducible and can be used effectively on fresh and aged slides. The following observations have been made: (1) a core existed in mitotic chromosomes in all the materials employed, confirming the findings of Howell and Hus (1979). (2) The microchromosomes of the chicken and double minutes of a human carcinoma cell line also exhibited the core structure. (3) The core structure of meiotic chromosomes appear weak, disorganized, and disintegrating.