Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 169
Filtrar
1.
Reprod Domest Anim ; 57(5): 459-464, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35098603

RESUMO

In mammals, spermatogenesis is a complex and cyclic process in which a spermatogonia turns into a highly differentiated cell: the spermatozoa. Spermatogenesis comprises proliferation of spermatogonia (spermatocytogenesis), meiosis of spermatocytes and finally differentiation of spermatids into spermatozoa (spermiogenesis). This review summarizes the current knowledge on domestic cat spermatogenesis including its physiology, development, efficiency and pathologies as well as their novel non-invasive diagnostic methods. This information will provide a resource for further studies to achieve precise fundamental knowledge of key aspects that will facilitate breeding, management and contraception in this popular species.


Assuntos
Espermátides , Espermatogênese , Animais , Gatos , Masculino , Mamíferos , Meiose , Espermátides/fisiologia , Espermatócitos/fisiologia , Espermatogênese/fisiologia , Espermatogônias , Espermatozoides/fisiologia , Testículo
2.
Zygote ; 28(4): 291-299, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32279700

RESUMO

Butterflyfish Chaetodon striatus is highly sought after in the marine ornamental aquarium, although studies about its reproductive biology are scarce. Therefore, to contribute to a better understanding of the reproductive aspects of C. striatus, we describe in detail with the use of high resolution histology the cellular dynamics of the germinal epithelium during the reproductive life history of this species. Based on the activity of the germinal epithelium, this study describes different stages of the gonadal development, similar to the reproductive phases found in other fish, to determine the reproductive period of C. striatus. In characterization of gonadal development, the following germ cells are described for males: spermatogonia, spermatocytes, spermatids and spermatozoa. Oogonia, early, primary, secondary, full-grown and maturing oocytes are described for females. Female germinal epithelium of C. striatus showed substantial changes over the study period, indicating that there was an active spawning period. Male germinal epithelium also presented relevant alterations, indicating reproductive activity in the testicular lobules. Morphological data confirm how informative was the cellular dynamics of the germinal epithelium for understanding gonadal development during adult reproductive life of fish in general. Although Chaetodon are a popular species, previous studies have only produced superficial and rough histological analyses. Therefore, this study demonstrates important information on germinal epithelium of Chaetodon. This knowledge could be a fundamental tool for development of new strategies for breeding of several species in captivity, especially butterflyfishes.


Assuntos
Oócitos/crescimento & desenvolvimento , Ovário/crescimento & desenvolvimento , Perciformes/crescimento & desenvolvimento , Espermatozoides/crescimento & desenvolvimento , Testículo/crescimento & desenvolvimento , Animais , Brasil , Células Epiteliais , Epitélio/metabolismo , Feminino , Masculino , Oogênese/fisiologia , Ovário/anatomia & histologia , Ovário/citologia , Espermátides/fisiologia , Espermatócitos/fisiologia , Espermatogênese/fisiologia , Testículo/anatomia & histologia , Testículo/citologia
3.
Theriogenology ; 142: 363-367, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31711695

RESUMO

The seminiferous epithelium goes through multiple changes which enables the differentiation of a spermatogonia in a fully mature spermatozoon. The timing of these changes is species-specific and influences the duration of the reproductive cycles. Bats are among wild mammals whose coordination between male and female reproductive cycles are imperative, since most females show seasonal preferences, even in the Tropics. This seasonal variation demands constant sperm production ready for spermiation in order to guarantee its genetic dispersion and reproduction success. Despite their abundance, little is known about the duration of reproductive cycles in Neotropical bat species, a relevant information for the species management and for conservational strategies regarding anthropogenic and climate influences on bats reproduction. In this study, we aimed at characterizing the stages of the seminiferous epithelium cycle (SEC) of the fruit bat Artibeus lituratus and to determine its duration based on the immunohistochemical analysis of the bromodeoxyuridine (BrDU) activity. SEC stages were characterized according to the tubular morphology method and the frequency of each stage was estimated. After intratesticular injections of BrDU, the animals were euthanized at different times, and the estimation of SEC duration was performed by observing the most advanced germ cells in the seminiferous epithelium. The most advanced stained cells after 2 days of BrdU injection were the primary spermatocytes in pachytene, transitioning from stages 1-2 of the SEC. Within 2 days, we found a progression of 30.42% of the SEC, and an entire cycle lasted 6.58 days on average. Considering that 4.5 seminiferous epithelium cycles are necessary for the whole spermatogenic processes to be completed, the total length of spermatogenesis in A. lituratus was estimated at 29.61 days. Our findings support a pattern of bimodal seasonal polyestry for this species, with rapid spermatogenic cycles.


Assuntos
Diferenciação Celular , Quirópteros/fisiologia , Epitélio Seminífero/citologia , Epitélio Seminífero/fisiologia , Espermatogênese/fisiologia , Animais , Masculino , Reprodução/fisiologia , Túbulos Seminíferos/citologia , Túbulos Seminíferos/fisiologia , Maturação do Esperma , Espermatócitos/citologia , Espermatócitos/fisiologia , Espermatogônias/citologia , Espermatogônias/fisiologia , Fatores de Tempo
4.
Zoologia (Curitiba) ; 36: e.30610, Nov. 25, 2019. ilus, tab, graf
Artigo em Inglês | VETINDEX | ID: vti-24619

RESUMO

The gonadal development of the characin Astyanax aff. bimaculatus from Funil Reservoir, an impoundment in the middle reaches of the Paraiba do Sul River in southeastern Brazil was analysed through histological, histochemical and histometric techniques, and the spawning season was determined. Unbalanced sex ratio was found, with females outnumbering and reaching larger sizes than males. The following stages of oogenic cell development were identified for females: primary growth, pre-vitellogenic (cortical alveolar) and vitellogenic. In males, the following stages were determined: spermatogonia primary and secondary, spermatocyte primary and secondary, spermatid and spermatozoa. The spawning occurs most of the year, peaking in January-February, as indicated by the gonadosomatic index. In the peak of the spawning period, the condition factor and hepatosomatic indices decreased suggesting use of stored body energy reserves during the reproduction. Spawning in batches, small-sized oocytes and a long reproductive season suggest that Astyanax aff. bimaculatus fits to an opportunist strategy. Such strategy may facilitate the use of a wide range of lentic and lotic body waters in the Neotropical region.(AU)


Assuntos
Animais , Gônadas/crescimento & desenvolvimento , Characidae/crescimento & desenvolvimento , Characidae/fisiologia , Reprodução , Oócitos , Espermatócitos , Reservatórios de Água , Brasil
5.
Zygote ; 27(6): 432-435, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31422785

RESUMO

Long-term heat stress (HS) induced by testicular insulation generates oxidative stress (OS) on the testicular environment; consequently activating antioxidant enzymes such as superoxide dismutase (SOD), glutathione reductase (GR) and glutathione peroxidase (GPx). The aim of this work was to immunolocalize antioxidant enzymes present in different cells within the seminiferous tubule when rams were submitted to HS. Rams were divided into control (n = 6) and treated group (n = 6), comprising rams subjected to testicular insulation for 240 h. After the testicular insulation period, rams were subjected to orchiectomy. Testicular fragments were submitted to immunohistochemistry for staining against SOD, GR and GPx enzymes. We observed immunolocalization of GPx in more cell types of the testis after HS and when compared with other enzymes. In conclusion, GPx is the main antioxidant enzyme identified in testicular cells in an attempt to maintain oxidative balance when HS occurs.


Assuntos
Glutationa Peroxidase/metabolismo , Glutationa Redutase/metabolismo , Resposta ao Choque Térmico/fisiologia , Túbulos Seminíferos/enzimologia , Superóxido Dismutase/metabolismo , Testículo/enzimologia , Animais , Antioxidantes/metabolismo , Imuno-Histoquímica/métodos , Masculino , Orquiectomia , Estresse Oxidativo/fisiologia , Túbulos Seminíferos/citologia , Ovinos , Espermátides/citologia , Espermátides/enzimologia , Espermatócitos/citologia , Espermatócitos/enzimologia , Espermatogônias/citologia , Espermatogônias/enzimologia , Testículo/citologia , Fatores de Tempo
6.
Anat Rec (Hoboken) ; 302(11): 2082-2092, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31168949

RESUMO

Apoptosis is a type of cell death responsible for maintaining tissue homeostasis that can occur in male gonads. The morphological and biochemical characteristics of apoptosis include cellular contraction, caspase activation, and DNA fragmentation. Dynamic processes of cell renewal and differentiation occur inside the seminiferous tubules, which are regulated by mitosis and meiosis, respectively. During meiosis, recombination is caused by assembly of the synaptonemal complex, which involves the participation of constitutive proteins, such as synaptonemal complex protein-3 (SYCP3). The present study evaluated germinal cell death in immature male rats and the distribution of the SYCP3 protein. Our results indicate that as germinal cells progress to the second meiotic stage, significant numbers of them are eliminated by apoptosis. We determined that the SYCP3 protein is not always incorporated into the structure of the synaptonemal complex but rather forms a nuclear cumulus near the inner nuclear membrane, causing many of these cells to undergo apoptosis. We propose that both the excess of the SYCP3 protein and its accumulation during the first meiotic division could contribute to the cell death of primary spermatocytes during the first spermatogenic wave in prepubertal Wistar rats. Anat Rec, 302:2082-2092, 2019. © 2019 American Association for Anatomy.


Assuntos
Apoptose , Proteínas de Ligação a DNA/metabolismo , Espermatócitos/metabolismo , Espermatócitos/patologia , Espermatogênese , Animais , Imuno-Histoquímica , Masculino , Meiose , Ratos , Ratos Wistar
7.
Zoologia (Curitiba, Impr.) ; 36: e.30610, Apr. 18, 2019. ilus, tab, graf
Artigo em Inglês | VETINDEX | ID: biblio-1504566

RESUMO

The gonadal development of the characin Astyanax aff. bimaculatus from Funil Reservoir, an impoundment in the middle reaches of the Paraiba do Sul River in southeastern Brazil was analysed through histological, histochemical and histometric techniques, and the spawning season was determined. Unbalanced sex ratio was found, with females outnumbering and reaching larger sizes than males. The following stages of oogenic cell development were identified for females: primary growth, pre-vitellogenic (cortical alveolar) and vitellogenic. In males, the following stages were determined: spermatogonia primary and secondary, spermatocyte primary and secondary, spermatid and spermatozoa. The spawning occurs most of the year, peaking in January-February, as indicated by the gonadosomatic index. In the peak of the spawning period, the condition factor and hepatosomatic indices decreased suggesting use of stored body energy reserves during the reproduction. Spawning in batches, small-sized oocytes and a long reproductive season suggest that Astyanax aff. bimaculatus fits to an opportunist strategy. Such strategy may facilitate the use of a wide range of lentic and lotic body waters in the Neotropical region.


Assuntos
Animais , Characidae/crescimento & desenvolvimento , Characidae/fisiologia , Espermatócitos , Gônadas/crescimento & desenvolvimento , Oócitos , Reprodução , Brasil , Reservatórios de Água
8.
J Mol Histol ; 50(3): 189-202, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30911868

RESUMO

The cilia and flagella of eukaryotic cells serve many functions, exhibiting remarkable conservation of both structure and molecular composition in widely divergent eukaryotic organisms. SPAG6 and SPAG16 are the homologous in the mice to Chlamydomonas reinhardtii PF16 and PF20. Both proteins are associated with the axonemal central apparatus and are essential for ciliary and flagellar motility in mammals. Recent data derived from high-throughput studies revealed expression of these genes in tissues that do not contain motile cilia. However, the distribution of SPAG6 and SPAG16 in ciliated and non-ciliated tissues is not completely understood. In this work, we performed a quantitative analysis of the expression of Spag6 and Spag16 genes in parallel with the immune-localization of the proteins in several tissues of adult mice. Expression of mRNA was higher in the testis and tissues bearing motile cilia than in the other analyzed tissues. Both proteins were present in ciliated and non-ciliated tissues. In the testis, SPAG6 was detected in spermatogonia, spermatocytes, and in the sperm flagella whereas SPAG16 was found in spermatocytes and in the sperm flagella. In addition, both proteins were detected in the cytoplasm of cells from the brain, spinal cord, and ovary. A small isoform of SPAG16 was localized in the nucleus of germ cells and some neurons. In a parallel set of experiments, we overexpressed EGFP-SPAG6 in cultured cells and observed that the protein co-localized with a subset of acetylated cytoplasmic microtubules. A role of these proteins stabilizing the cytoplasmic microtubules of eukaryotic cells is discussed.


Assuntos
Cílios/genética , Proteínas dos Microtúbulos/genética , Proteínas Associadas aos Microtúbulos/genética , Neurônios/metabolismo , Animais , Chlamydomonas reinhardtii/genética , Cílios/metabolismo , Epêndima/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/genética , Masculino , Camundongos , Proteínas dos Microtúbulos/isolamento & purificação , Proteínas Associadas aos Microtúbulos/isolamento & purificação , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Espermatócitos/metabolismo , Espermatogônias/metabolismo
9.
Genes (Basel) ; 10(2)2019 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-30736350

RESUMO

We studied and compared the nucleolar expression or nucleoli from specific bivalents in spermatocytes of the standard Mus musculus domesticus 2n=40, of Robertsonian (Rb) homozygotes 2n = 24 and heterozygotes 2n = 32. We analyzed 200 nuclear microspreads of each specific nucleolar chromosome and spermatocyte karyotype, using FISH to identify specific nucleolar bivalents, immunofluorescence for both fibrillarin of the nucleolus and the synaptonemal complex of the bivalents, and DAPI for heterochromatin. There was nucleolar expression in all the chromosomal conditions studied. By specific nucleolar bivalent, the quantitative relative nucleolar expression was higher in the bivalent 12 than in its derivatives, lower in the bivalent 15 than in its derivatives and higher in the bivalent 16 than its Rb derivatives. In the interactions between non-homologous chromosomal domains, the nucleolar bivalents were preferentially associated through pericentromeric heterochromatin with other bivalents of similar morphology and sometimes with other nucleolar bivalents. We suggest that the nucleolar expression in Rb nucleolar chromosomes is modified as a consequence of different localization of ribosomal genes (NOR) in the Rb chromosomes, its proximity to heterochromatin and its associations with chromosomes of the same morphology.


Assuntos
Nucléolo Celular/genética , Espermatócitos/metabolismo , Translocação Genética , Animais , Cromossomos/genética , Cromossomos/metabolismo , Homozigoto , Masculino , Camundongos , Espermatócitos/citologia
10.
J Therm Biol ; 77: 14-23, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30196893

RESUMO

Temperature is considered a crucial modulator of reproductive activity and testis homeostasis. It is well known that elevated temperatures cause several effects on testicular components, particularly on germ cells, which might lead to the impairment of spermatogenesis and loss of male fertility. The present study aimed to evaluate the effects of different environmental temperatures on several morphofunctional testis parameters, with emphasis on duration of spermatogenesis and spermatogenic efficiency. Thirty sexually mature Swiss mice (Mus musculus) were allocated in three different experimental groups, being kept in vivarium for three weeks at 16 °C, 23 °C (control group) and 32 °C. In order to estimate the duration of spermatogenesis, three animals per each group received intraperitoneal injections of tritiated thymidine and the testes were perfused-fixed and routinely processed for histological, morphometrical and immunoperoxidase analyses. Although the lower temperature (16 °C) did not change most of the evaluated testicular parameters, our findings showed that higher environmental temperature (32 °C) is able to alter important testis parameters, resulting for instance in acceleration of spermatogenesis, alterations in the stages frequencies, increased number of germ and Leydig cells apoptosis and reduced Sertoli cell and spermatogenic efficiencies. As in many conditions infertile men exhibit higher mean scrotal temperature, we believe that experimental studies with mice involving temperature might represent an interesting approach to better understand the mechanisms related to human testis function and sperm production.


Assuntos
Espermatogênese , Testículo/fisiologia , Termotolerância , Animais , Apoptose , Temperatura Corporal , Temperatura Alta , Infertilidade Masculina , Masculino , Camundongos , Células de Sertoli/citologia , Células de Sertoli/metabolismo , Células de Sertoli/ultraestrutura , Espermatócitos/citologia , Espermatócitos/metabolismo , Espermatozoides/citologia , Espermatozoides/fisiologia , Espermatozoides/ultraestrutura , Testículo/citologia , Testículo/ultraestrutura , Testosterona/sangue
11.
J Math Biol ; 77(5): 1341-1362, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-29922920

RESUMO

We show that an inhomogeneous Bernoulli site percolation process running upon a fullerene's dual [Formula: see text] can be used for representing bivalents attached to the nuclear envelope in mouse Mus M. Domesticus 2n = 40 meiotic spermatocytes during pachytene. It is shown that the induced clustering generated by overlapping percolation domains correctly reproduces the probability distribution observed in the experiments (data) after fine tuning the parameters.


Assuntos
Cromossomos/genética , Meiose , Modelos Genéticos , Espermatócitos/ultraestrutura , Animais , Cromossomos/ultraestrutura , Simulação por Computador , Heterocromatina/genética , Heterocromatina/ultraestrutura , Masculino , Conceitos Matemáticos , Meiose/genética , Camundongos , Membrana Nuclear/genética , Membrana Nuclear/ultraestrutura , Estágio Paquíteno/genética , Complexo Sinaptonêmico/genética , Complexo Sinaptonêmico/ultraestrutura
12.
J Lipid Res ; 59(7): 1175-1189, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29724783

RESUMO

The sphingolipids (SLs) of rodent spermatogenic cells (spermatocytes, spermatids) and spermatozoa contain nonhydroxylated and 2-hydroxylated versions of very-long-chain (C26-C32) PUFAs (n-V and h-V, respectively) not present in Sertoli cells (SCs). Here, we investigated the expression of selected fatty acid elongases [elongation of very-long-chain fatty acid protein (Elovl)], with a focus on Elovl4, and a fatty acid 2-hydroxylase (Fa2h) in rat testes with postnatal development and germ cell differentiation. Along with Elovl5 and Elovl2, Elovl4 was actively transcribed in the adult testis. Elovl4 mRNA levels were high in immature testes and SCs, though the protein was absent. The Elovl4 protein was a germ cell product. All cells under study elongated [3H]arachidonate to tetraenoic and pentaenoic C24 PUFA, but only germ cells produced C26-C32 PUFAs. Spermatocytes displayed the highest Elovl4 protein levels and enzymatic activity. Fa2h mRNA was produced exclusively in germ cells, mostly round spermatids. As a protein, Fa2h was mainly concentrated in late spermatids, in the step of spermiogenesis in which they elongate and their heads change shape. The expression of Elovl4 and Fa2h thus correlate with the abundance of n-Vs and h-Vs in the SLs of rat spermatocytes and spermatids, respectively.


Assuntos
Amidoidrolases/genética , Proteínas do Olho/genética , Ácidos Graxos Insaturados/metabolismo , Regulação da Expressão Gênica , Proteínas de Membrana/genética , Espermatócitos/metabolismo , Espermatogênese/genética , Esfingolipídeos/metabolismo , Animais , Masculino , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Espermátides/citologia , Espermátides/metabolismo , Espermatócitos/citologia
13.
Zygote ; 26(2): 127-134, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29573758

RESUMO

SummaryThe Deleted in AZoospermia (DAZ) gene family regulates the development, maturation and maintenance of germ cells and spermatogenesis in mammals. The DAZ family consists of two autosomal genes, Boule and Dazl (Daz-like), and the Daz gene on chromosome Y. The aim of this study was to analyze the localization of DAZL and BOULE during testicular ontogeny of the seasonal-breeding Syrian hamster, Mesocricetus auratus. We also evaluated the testicular expression of DAZ family genes under short- or long-photoperiod conditions. In the pre-pubertal and adult testis, DAZL protein was found mainly in spermatogonia. BOULE was found in the spermatogonia from 20 days of age and during the pre-pubertal and adult period it was also detected in spermatocytes and round spermatids. DAZL and BOULE expression in spermatogonia was strictly nuclear only in 20-day-old hamsters. We also detected the novel mRNA and protein expression of BOULE in Leydig cells. In adult hamsters, Dazl expression was increased in regressed testis compared with non-regressed testis and DAZL protein expression was restricted to primary spermatocytes in regressed testis. These results show that DAZL and BOULE are expressed in spermatogonia at early stages in the Syrian hamster, then both proteins translocate to the cytoplasm when meiosis starts. In the adult regressed testis, the absence of DAZL in spermatogonia might be related to the decrease in germ cell number, suggesting that DAZ gene family expression is involved in changes in seminiferous epithelium during photoregression.


Assuntos
Fotoperíodo , Proteínas de Ligação a RNA/genética , Testículo/fisiologia , Fatores Etários , Animais , Regulação da Expressão Gênica , Células Intersticiais do Testículo/metabolismo , Masculino , Mesocricetus , Proteínas de Ligação a RNA/metabolismo , Espermatócitos/metabolismo , Espermatogônias/metabolismo , Testículo/citologia
14.
Aquat Toxicol ; 194: 86-93, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29169052

RESUMO

Tebuthiuron is a phenylurea herbicide widely used in agriculture that can reach the aquatic environments, possibly posing negative effects to the aquatic biota. Phenylurea herbicides, such as diuron, are known to cause estrogenic and anti-androgenic effects in fish, but no such effects were yet reported for tebuthiuron exposure. Thus, the aim of this study was to evaluate if tebuthiuron, at environmentally relevant concentrations (100 and 200ng/L) and after 25days of exposure have estrogenic and/or anti-androgenic effects on male of Nile tilapia (Oreochromis niloticus), through the evaluation of plasmatic testosterone (T) and estradiol (E2) levels, brain aromatase (CYP19) levels (western-blot), and by evaluating the histology of the testicles. When compared to the control group, plasmatic T levels decreased about 76% in the animals exposed to 200ng/L of tebuthiuron, while E2 levels increased about 94%, which could be related to a significant increase (77%) in CYP19A1 levels, an enzyme that catalyzes the conversion of androgens into estrogens. Histological analyses of the testicles also demonstrated that tebuthiuron at both tested concentrations caused a decrease in the diameter of the seminiferous tubules and in the diameter of the lumen. Therefore, the gonadosomatic index (GSI) was reduced by 36% % in the animals exposed 200ng/L to tebuthiuron. Indeed, the relative frequency of spermatocytes and spermatids increased respectively 73% (200ng/L) and 61% (100ng/L) in the tebuthiuron exposed animals, possibly due to the impairment of sperm release into the lumen, that was decreased 93% (200ng/L) in the treated animals compared to the control. These results confirm that tebuthiuron causes estrogenic and anti-androgenic effects in Nile tilapias at environmentally relevant concentrations.


Assuntos
Encéfalo/efeitos dos fármacos , Ciclídeos/fisiologia , Herbicidas/toxicidade , Compostos de Metilureia/toxicidade , Testículo/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Aromatase/metabolismo , Encéfalo/enzimologia , Ciclídeos/crescimento & desenvolvimento , Estradiol/sangue , Masculino , Espermatócitos/efeitos dos fármacos , Testículo/patologia , Testosterona/sangue
15.
Biol Res ; 50(1): 38, 2017 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-29169375

RESUMO

BACKGROUND: The nuclear architecture of meiotic prophase spermatocytes is based on higher-order patterns of spatial associations among chromosomal domains and consequently is prone to modification by chromosomal rearrangements. We have shown that nuclear architecture is modified in spermatocytes of Robertsonian (Rb) homozygotes of Mus domesticus. In this study we analyse the synaptic configuration of the quadrivalents formed in the meiotic prophase of spermatocytes of mice double heterozygotes for the dependent Rb chromosomes: Rbs 11.16 and 16.17. RESULTS: Electron microscope spreads of 60 pachytene spermatocytes from four animals of Mus domesticus 2n = 38 were studied and their respective quadrivalents analysed in detail. Normal synaptonemal complex was found between arms 16 of the Rb metacentric chromosomes, telocentrics 11 and 17 and homologous arms of the Rb metacentric chromosomes. About 43% of the quadrivalents formed a synaptonemal complex between the heterologous short arms of chromosomes 11 and 17. This synaptonemal complex is bound to the nuclear envelope through a fourth synapsed telomere, thus dragging the entire quadrivalent to the nuclear envelope. About 57% of quadrivalents showed unsynapsed single axes in the short arms of the telocentric chromosomes. About 90% of these unsynapsed quadrivalents also showed a telomere-to-telomere association between one of the single axes of the telocentric chromosome 11 or 17 and the X chromosome single axis, which was otherwise normally paired with the Y chromosome. Nucleolar material was associated with two bivalents and with the quadrivalent. CONCLUSIONS: The spermatocytes of heterozygotes for dependent Rb chromosomes formed a quadrivalent where four chromosomes are synapsed together and bound to the nuclear envelope through four telomeres. The nuclear configuration is determined by the fourth shortest telomere, which drags the centromere regions and heterochromatin of all the chromosomes towards the nuclear envelope, favouring the reiterated encounter and eventual rearrangement between the heterologous chromosomes. The unsynapsed regions of quadrivalents are frequently bound to the single axis of the X chromosome, possibly perturbing chromatin condensation and gene expression.


Assuntos
Nucléolo Celular/fisiologia , Espermatócitos/fisiologia , Espermatócitos/ultraestrutura , Complexo Sinaptonêmico/fisiologia , Cromossomo X/fisiologia , Cromossomo Y/fisiologia , Animais , Nucléolo Celular/genética , Heterocromatina/genética , Heterocromatina/fisiologia , Heterozigoto , Masculino , Prófase Meiótica I/genética , Prófase Meiótica I/fisiologia , Camundongos , Complexo Sinaptonêmico/genética , Telômero/genética , Telômero/fisiologia , Translocação Genética , Cromossomo X/genética , Cromossomo Y/genética
16.
Zygote ; 25(4): 537-544, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28766472

RESUMO

This study aimed to examine the gonadal morphology of diploid and triploid fish through stereological analysis. Triploid individuals were obtained after temperature shock (40°C for 2 min) at 2 min post-fertilization and reared until 175 days post-fertilization (dpf). Intact eggs were used to obtain the diploids. Gonads were collected for histological analysis at 83, 114, 144 and 175 dpf. Diploid females and males presented normal oogenesis and spermatogenesis through all the experimental period. Conversely, stereological analysis revealed that triploid females were sterile and oogonia were the prevalent cell type in the ovaries. Triploid males presented increased amounts of spermatocyte cysts and a large area of lumen when compared with diploids and in addition the amount of spermatozoa was lower than that observed for diploids. However, some triploid males presented spermatogenesis similar to diploids. Therefore, we concluded that triploidization is an interesting alternative to produce sterile individuals in A. altiparanae.


Assuntos
Characidae/fisiologia , Diploide , Ovário/citologia , Testículo/citologia , Triploidia , Animais , Contagem de Células , Characidae/genética , Feminino , Masculino , Oócitos/fisiologia , Oogênese , Ovário/fisiologia , Espermatócitos , Espermatogênese , Testículo/fisiologia
17.
Cytogenet Genome Res ; 152(3): 137-147, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28848076

RESUMO

The heteromorphic X and Y chromosomes behave in a special way in mammalian spermatocytes; they form the XY body and synapse only partially. The aim of this article was to study the origin and the role of the special differentiations in the XY pair of the domestic cat during pachytene by analyzing its fine structural characteristics and the immunolocalization of the main meiotic proteins SYCP3, SYCP1, SYCE3, SMC3, γ-H2AX, BRCA1, H3K27me3, and MLH1. The cat XY body shows particularly striking structures: an extreme degree of axial fibrillation in late pachynema and a special location of SYCP3-containing fibrils, bridging different regions of the main X axis, as well as one bridge at the inner end of the pairing region that colocalizes with the single mandatory MLH1 focus. There are sequential changes, first bullous expansions, then subdivision into fibrils, all involving axial thickening. The chromatin of the XY body presents the usual features of meiotic sex chromosome inactivation. An analysis of the XY body of many eutherians and metatherians suggests that axial thickenings are primitive features. The sequential changes in the mass and location of SYCP3-containing fibers vary among the clades because of specific processes of axial assembly/disassembly occurring in different species.


Assuntos
Gatos/genética , Proteínas Nucleares/metabolismo , Estágio Paquíteno/genética , Complexo Sinaptonêmico/metabolismo , Cromossomo X/metabolismo , Cromossomo X/ultraestrutura , Cromossomo Y/metabolismo , Cromossomo Y/ultraestrutura , Animais , Proteína BRCA1/genética , Proteína BRCA1/metabolismo , Cromatina/metabolismo , Cromatina/ultraestrutura , Histonas/genética , Histonas/metabolismo , Masculino , Microscopia de Fluorescência , Proteína 1 Homóloga a MutL/genética , Proteína 1 Homóloga a MutL/metabolismo , Espermatócitos/metabolismo , Complexo Sinaptonêmico/genética
18.
Zygote ; 25(4): 498-506, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28693627

RESUMO

Japanese fancy mouse, mini mouse or pet mouse are common names used to refer to strains of mice that present with different colour varieties and coat types. Although many genetic studies that involve spotting phenotype based on the coat have been performed in these mice, there are no reports of quantitative data in the literature regarding testis structure and spermatogenic efficiency. Hence, in this study we researched testis function and spermatogenesis in the adult Japanese fancy mouse. The following values of 68 ± 6 mg and 0.94 ± 0.1% were obtained as mean testis weight and gonadosomatic index, respectively. In comparison with other investigated mice strains, the fancy mouse Leydig cell individual size was much smaller, resulting in higher numbers of these cells per gram of testis. As found for laboratory mice strains, as a result of the development of the acrosomic system, 12 stages of the seminiferous epithelium cycle have been described in this study. The combined frequencies of pre-meiotic and post-meiotic stages were respectively 24% and 64% and very similar to the laboratory mice. The more differentiated germ cell types marked at 1 h or 9 days after tritiated thymidine administration were preleptotene/leptotene and pachytene spermatocytes at the same stage (VIII). The mean duration of one spermatogenic cycle was 8.8 ± 0.01 days and the total length of spermatogenesis lasted 37.8 ± 0.01 days (4.5 cycles). A high number of germ cell apoptosis was evident during meiosis, resulting in lower Sertoli cell and spermatogenic efficiencies, when compared with laboratory mice strains.


Assuntos
Espermatogênese/fisiologia , Testículo/citologia , Testículo/fisiologia , Animais , Contagem de Células , Células Intersticiais do Testículo , Masculino , Camundongos , Tamanho do Órgão , Epitélio Seminífero/citologia , Epitélio Seminífero/fisiologia , Células de Sertoli , Espermátides/fisiologia , Espermatócitos , Testículo/anatomia & histologia
19.
Cytogenet Genome Res ; 151(2): 61-71, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28494440

RESUMO

The nuclear organization of spermatocytes in meiotic prophase I is primarily determined by the synaptic organization of the bivalents that are bound by their telomeres to the nuclear envelope and described as arc-shaped trajectories through the 3D nuclear space. However, over this basic meiotic organization, a spermatocyte nuclear architecture arises that is based on higher-ordered patterns of spatial associations among chromosomal domains from different bivalents that are conditioned by the individual characteristics of chromosomes and the opportunity for interactions between their domains. Consequently, the nuclear architecture is species-specific and prone to modification by chromosomal rearrangements. This model is valid for the localization of any chromosomal domain in the meiotic prophase nucleus. However, constitutive heterochromatin plays a leading role in shaping nuclear territories. Thus, the nuclear localization of nucleoli depends on the position of NORs in nucleolar bivalents, but the association among nucleolar chromosomes mainly depends on the presence of constitutive heterochromatin that does not affect the expression of the ribosomal genes. Constitutive heterochromatin and nucleoli form complex nuclear territories whose distribution in the nuclear space is nonrandom, supporting the hypothesis regarding the existence of a species-specific nuclear architecture in first meiotic prophase spermatocytes.


Assuntos
Nucléolo Celular/genética , Cromossomos , Heterocromatina , Espermatócitos/citologia , Animais , Nucléolo Celular/ultraestrutura , Heterocromatina/química , Heterocromatina/genética , Heterocromatina/metabolismo , Masculino , Prófase Meiótica I , Camundongos , Região Organizadora do Nucléolo , Espermatócitos/fisiologia , Espermatócitos/ultraestrutura , Telômero , Translocação Genética
20.
Cytogenet Genome Res ; 151(3): 131-140, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28402969

RESUMO

For brown howler monkeys (Alouatta guariba clamitans), diploid chromosome numbers varying from 2n = 45 to 2n = 52, with XX/XY, X1X1X2X2/X1X2Y, and X1X1X2X2X3X3/X1X2X3Y1Y2 sex chromosome systems have been described by mitotic studies but still await confirmation by meiotic analyses. We analyzed 3 male individuals sampled in the wild (in the municipality of Santa Maria, RS, Brazil) as well as 1 male and 1 female individual in captivity at the São Braz breeding center. Peripheral blood samples and testicular biopsies were taken. We found different diploid numbers for both sexes in somatic cells, 2n = 45,X1X2X3Y1Y2 in males and 2n = 46,X1X1X2X2X3X3 in females, with 4 metacentric (9-12), 7 submetacentric (1-6, 8), and 9 acrocentric autosomal chromosome pairs (13-20, 22). X1 and X2 were submetacentric chromosomes, while X3, Y1, and Y2 were acrocentric ones. Spermatocyte microspreads were examined for synaptonemal complexes. Pachytene spermatocyte analysis was done to verify the chromosome number and morphologies observed in mitotic karyotypes. Immunodetection was performed using anti-SMC3 and anti-CREST antibodies. The presence of a sex chromosome pentavalent X1X2X3Y1Y2 in the males was confirmed by C-banding in metaphase I and by immunodetection in prophase I by the clear identification of 5 centromeres. The G-banded karyotype corresponded to that previously described for A. g. clamitans in the south of Brazil (Curitiba, Parana State, and Blumenau, Santa Catarina State) and for the Misiones Province, Argentina.


Assuntos
Alouatta/genética , Cromossomos Sexuais/genética , Processos de Determinação Sexual , Alouatta/fisiologia , Animais , Análise Citogenética/veterinária , Feminino , Células Germinativas/citologia , Masculino , Meiose , Espermatócitos/citologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA