RESUMO
Cell differentiation, proliferation, and morphogenesis are generally driven by instructive signals that are sent and interpreted by adjacent tissues, a process known as induction. Cell recruitment is a particular case of induction in which differentiated cells produce a signal that drives adjacent cells to differentiate into the same type as the inducers. Once recruited, these new cells may become inducers to continue the recruitment process, closing a feed-forward loop that propagates the growth of a specific cell-type population. So far, little attention has been given to cell recruitment as a developmental mechanism. Here, we review the components of cell recruitment and discuss its contribution to development in three different examples: the Drosophila wing, the vertebrate inner ear, and the mammalian thyroid gland. Finally, we posit some open questions about the role of cell recruitment in organ patterning and growth.
Assuntos
Drosophila , Mamíferos , Morfogênese , Vertebrados , Animais , Drosophila/embriologia , Orelha Interna/embriologia , Regulação da Expressão Gênica no Desenvolvimento , Mamíferos/embriologia , Glândula Tireoide/embriologia , Vertebrados/embriologia , Asas de Animais/embriologiaRESUMO
The use of antibacterial substances as additives in extenders for ensuring the sanitary quality of the semen employed in reproductive biotechniques and preserving it from bacterial deterioration has been reported since the mid-twentieth century. However, the deleterious effects of these drugs on the sperm quality as well as their effectiveness in controlling bacterial growth in the preserved semen have been questioned. The aim of this review was to report the antimicrobials primarily used in the extenders added to the semen of mammals, and to present alternatives to their use. Among the various mammalian species, there is a large variation regarding the antimicrobial types added to semen extenders as cephalosporins (ceftiofur, cefdinir, eg) and quinolones (ofloxacin, ciprofloxacin), alone or in combination with large action spectra substances as penicillin-streptomycin and gentamicin-tylosin-lincomycin-spectinomycin. To combat problems related to bacterial resistance to these drugs, the emergence of alternatives is increasingly evident. Among these alternatives, use of physical methods as centrifugation and filtration, as well as the use of antimicrobial peptides and other substances from different origins have been highlighted for presenting antimicrobial potential.
Assuntos
Masculino , Animais , Antibacterianos/análise , Análise do Sêmen/veterinária , Biotecnologia , Mamíferos/embriologiaRESUMO
The use of antibacterial substances as additives in extenders for ensuring the sanitary quality of the semen employed in reproductive biotechniques and preserving it from bacterial deterioration has been reported since the mid-twentieth century. However, the deleterious effects of these drugs on the sperm quality as well as their effectiveness in controlling bacterial growth in the preserved semen have been questioned. The aim of this review was to report the antimicrobials primarily used in the extenders added to the semen of mammals, and to present alternatives to their use. Among the various mammalian species, there is a large variation regarding the antimicrobial types added to semen extenders as cephalosporins (ceftiofur, cefdinir, eg) and quinolones (ofloxacin, ciprofloxacin), alone or in combination with large action spectra substances as penicillin-streptomycin and gentamicin-tylosin-lincomycin-spectinomycin. To combat problems related to bacterial resistance to these drugs, the emergence of alternatives is increasingly evident. Among these alternatives, use of physical methods as centrifugation and filtration, as well as the use of antimicrobial peptides and other substances from different origins have been highlighted for presenting antimicrobial potential.(AU)
Assuntos
Animais , Masculino , Mamíferos/embriologia , Biotecnologia , Antibacterianos/análise , Análise do Sêmen/veterináriaRESUMO
Androgens and anti-Müllerian hormone (AMH), secreted by the foetal testis, are responsible for the development of male reproductive organs and the regression of female anlagen. Virilization of the reproductive tract in association with the absence of Müllerian derivatives in the XX foetus implies the existence of testicular tissue, which can occur in the presence or absence of SRY. Recent advancement in the knowledge of the opposing gene cascades driving to the differentiation of the gonadal ridge into testes or ovaries during early foetal development has provided insight into the molecular explanation of XX maleness.
Assuntos
Transtornos do Desenvolvimento Sexual/genética , Diferenciação Sexual/genética , Animais , Feto/embriologia , Humanos , Masculino , Mamíferos/embriologia , Modelos BiológicosRESUMO
Reproduction is a highly complex biologicalprocess requiring a dialogue between the developingconceptus (embryo-fetus and associated placentalmembranes) and maternal uterus which must beestablished during the peri-implantation period forpregnancy recognition signaling and regulation of geneexpression by uterine epithelial and stromal cells. Theuterus provide a microenvironment in which moleculessecreted by uterine epithelia or transported into theuterine lumen represent histotroph or the secretomerequired for growth and development of the conceptusand receptivity of the uterus to implantation by theconceptus. Pregnancy recognition signaling as related tosustaining the functional lifespan of the corpora lutea(CL) which produce progesterone; the hormone ofpregnancy essential for uterine functions that supportimplantation and placentation required for successfuloutcomes of pregnancy. It is within the periimplantationperiod that most embryonic deaths occur inmammals due to deficiencies attributed to uterinefunctions or failure of the conceptus to developappropriately, signal pregnancy recognition and/orundergo implantation and placentation. The endocrinestatus of the pregnant female and her nutritional status arecritical for successful establishment and maintenance ofpregnancy. The challenge is to understand the complexityof key mechanisms that are characteristic of successfulreproduction and to use that knowledge to enhancefertility and reproductive health of animals includingnonhuman primates. It is important to translateknowledge gained from studies of animals to addressissues of fertility and reproductive health in humans.
Assuntos
Feminino , Animais , Estrogênios/análise , Estrogênios/síntese química , Gravidez , Mamíferos/embriologia , FertilidadeRESUMO
Reproduction is a highly complex biologicalprocess requiring a dialogue between the developingconceptus (embryo-fetus and associated placentalmembranes) and maternal uterus which must beestablished during the peri-implantation period forpregnancy recognition signaling and regulation of geneexpression by uterine epithelial and stromal cells. Theuterus provide a microenvironment in which moleculessecreted by uterine epithelia or transported into theuterine lumen represent histotroph or the secretomerequired for growth and development of the conceptusand receptivity of the uterus to implantation by theconceptus. Pregnancy recognition signaling as related tosustaining the functional lifespan of the corpora lutea(CL) which produce progesterone; the hormone ofpregnancy essential for uterine functions that supportimplantation and placentation required for successfuloutcomes of pregnancy. It is within the periimplantationperiod that most embryonic deaths occur inmammals due to deficiencies attributed to uterinefunctions or failure of the conceptus to developappropriately, signal pregnancy recognition and/orundergo implantation and placentation. The endocrinestatus of the pregnant female and her nutritional status arecritical for successful establishment and maintenance ofpregnancy. The challenge is to understand the complexityof key mechanisms that are characteristic of successfulreproduction and to use that knowledge to enhancefertility and reproductive health of animals includingnonhuman primates. It is important to translateknowledge gained from studies of animals to addressissues of fertility and reproductive health in humans.(AU)
Assuntos
Animais , Feminino , Gravidez , Estrogênios/análise , Estrogênios/síntese química , Mamíferos/embriologia , FertilidadeRESUMO
Lipotoxicity is characterized by excessive saturated fatty acids in the blood, increasing storage in non-adipose cells, which leads to changes in the expression pattern of genes related to endoplasmic reticulum stress (e.g., ATF4, ATF6, CHOP, And GRP78), pro- and anti-apoptotic pathways (e.g., Baxand Bcl-2, and protein stability, including heat shock proteins, e.g., HSP70). A negative sub-cellular effect is usually an end result, which also occurs in the ovarian follicular population, affecting granulosa cells and cumulus-oocyte complexes (COCs), which leads to adecrease in oocyte quality and mitochondrial activity, and increased apoptosis. The addition of high doses of non-esterified fatty acids to oocyte in vitro maturation medium has been shown to slow the progression of meio sis, hampering oocyte maturation and subsequent in vitro embryo development. Due to its importance in the control of cellular lipid droplets and expression correlation with cytosolic lipid accumulation, the expression of the Plin 2 (Perilipin 2) Protein is also highlighted. The aim of this Review is to discuss some reproductive implications of dietary li pid supplementation in ruminant females, and the potential effects of lipotoxicityon oocyte qualityand reproduction, and the main mechanisms involved in the expression of genes related to endoplasmic reticulum stress and cellular lipid accumulation.(AU)
Assuntos
Animais , Feminino , Mamíferos/embriologia , Ácidos Graxos/sangue , Ácidos Graxos/toxicidade , Embrião de Mamíferos , Técnicas Reprodutivas/veterináriaRESUMO
Lipotoxicity is characterized by excessive saturated fatty acids in the blood, increasing storage in non-adipose cells, which leads to changes in the expression pattern of genes related to endoplasmic reticulum stress (e.g., ATF4, ATF6, CHOP, And GRP78), pro- and anti-apoptotic pathways (e.g., Baxand Bcl-2, and protein stability, including heat shock proteins, e.g., HSP70). A negative sub-cellular effect is usually an end result, which also occurs in the ovarian follicular population, affecting granulosa cells and cumulus-oocyte complexes (COCs), which leads to adecrease in oocyte quality and mitochondrial activity, and increased apoptosis. The addition of high doses of non-esterified fatty acids to oocyte in vitro maturation medium has been shown to slow the progression of meio sis, hampering oocyte maturation and subsequent in vitro embryo development. Due to its importance in the control of cellular lipid droplets and expression correlation with cytosolic lipid accumulation, the expression of the Plin 2 (Perilipin 2) Protein is also highlighted. The aim of this Review is to discuss some reproductive implications of dietary li pid supplementation in ruminant females, and the potential effects of lipotoxicityon oocyte qualityand reproduction, and the main mechanisms involved in the expression of genes related to endoplasmic reticulum stress and cellular lipid accumulation.
Assuntos
Feminino , Animais , Embrião de Mamíferos , Mamíferos/embriologia , Ácidos Graxos/sangue , Ácidos Graxos/toxicidade , Técnicas Reprodutivas/veterináriaRESUMO
The process of chromatin configuration remodeling within the mammalian oocyte nucleus or germinal vesicle (GV), which occurs towards the end of its differentiation phase before meiotic resumption, has received much attention and has been studied in several mammals. This review is aimed to highlight the relationship between changes in chromatin configurations and to both functional and structural modifications occurring in the oocyte nuclear compartment. During the extensive phase of meiotic arrest at the diplotene stage, the chromatin enclosed within the GV is subjected to several levels of regulation. Morphologically, the chromosomes lose their individuality and form a loose chromatin mass. Then the decondensed chromatin undergoes profound rearrangements during the final stages of oocyte growth in tight association with the acquisition of meiotic and developmental competence. Functionally, the discrete stages of chromatin condensation are characterized by different level of transcriptional activity, DNA methylation and covalent histone modifications. Interestingly, the program of chromatin rearrangement is not completely intrinsic to the oocyte, but follicular cells exert their regulatory actions through gap junction mediated communications and intracellular messenger dependent mechanism(s). With this in mind and since oocyte growth mostly relies on the bidirectional crosstalk with the follicular cells, experimental manipulation of large-scale chromatin configuration is discussed. Besides providing tools to determine the key cellular pathways involved in genome-wide chromatin modifications , the present findings will aid to the refinement of physiological culture systems that can have important implications in treating human infertility as well as managing breeding schemes in animal husband .(AU)
Assuntos
Humanos , Animais , Mamíferos/embriologia , Oócitos , Meiose , Montagem e Desmontagem da Cromatina/genética , Estruturas CromossômicasRESUMO
The process of chromatin configuration remodeling within the mammalian oocyte nucleus or germinal vesicle (GV), which occurs towards the end of its differentiation phase before meiotic resumption, has received much attention and has been studied in several mammals. This review is aimed to highlight the relationship between changes in chromatin configurations and to both functional and structural modifications occurring in the oocyte nuclear compartment. During the extensive phase of meiotic arrest at the diplotene stage, the chromatin enclosed within the GV is subjected to several levels of regulation. Morphologically, the chromosomes lose their individuality and form a loose chromatin mass. Then the decondensed chromatin undergoes profound rearrangements during the final stages of oocyte growth in tight association with the acquisition of meiotic and developmental competence. Functionally, the discrete stages of chromatin condensation are characterized by different level of transcriptional activity, DNA methylation and covalent histone modifications. Interestingly, the program of chromatin rearrangement is not completely intrinsic to the oocyte, but follicular cells exert their regulatory actions through gap junction mediated communications and intracellular messenger dependent mechanism(s). With this in mind and since oocyte growth mostly relies on the bidirectional crosstalk with the follicular cells, experimental manipulation of large-scale chromatin configuration is discussed. Besides providing tools to determine the key cellular pathways involved in genome-wide chromatin modifications , the present findings will aid to the refinement of physiological culture systems that can have important implications in treating human infertility as well as managing breeding schemes in animal husband .