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Trends in Parasitology Jul 2002Protozoan parasites of the phylum Apicomplexa have complex life cycles involving various types of asexual division that allow rapid proliferation of parasites within one... (Review)
Review
Protozoan parasites of the phylum Apicomplexa have complex life cycles involving various types of asexual division that allow rapid proliferation of parasites within one or more hosts. Such replication is punctuated by obligate sexual differentiation that produces male and female gametocytes. These stages are transmissible to haematophagous vectors or are necessary ultimately to form resistant cysts that are released into the environment. This article examines the sexual differentiation of apicomplexan parasites as it relates to the timing of commitment and the mechanism of the switch from asexual proliferation to the development of male and female sexual stages.
Topics: Animals; Apicomplexa; Evolution, Molecular; Female; Humans; Male; Sex Determination Processes; Sex Differentiation
PubMed: 12379952
DOI: 10.1016/s1471-4922(02)02292-4 -
Current Opinion in Pediatrics Aug 1996Cloning of the SRY sex-determining locus on the Y chromosome has stimulated research on the genetic mechanisms of sex determination. It now appears that SRY is not the... (Review)
Review
Cloning of the SRY sex-determining locus on the Y chromosome has stimulated research on the genetic mechanisms of sex determination. It now appears that SRY is not the only gene required for testicular differentiation; X-linked and autosomal genes are also important. In parallel, mutations of genes involved in somatic sex differentiation shed light on the mechanisms involved in testis-dependent events.
Topics: Gonads; Humans; Sex Chromosomes; Sex Differentiation; Testosterone
PubMed: 8954274
DOI: 10.1097/00008480-199608000-00017 -
International Journal of Molecular... May 2023Sex determination and differentiation are processes by which a bipotential gonad adopts either a testicular or ovarian cell fate, and secondary sexual characteristics... (Review)
Review
Sex determination and differentiation are processes by which a bipotential gonad adopts either a testicular or ovarian cell fate, and secondary sexual characteristics adopt either male or female developmental patterns. In birds, although genetic factors control the sex determination program, sex differentiation is sensitive to hormones, which can induce sex reversal when disturbed. Although these sex-reversed birds can form phenotypes opposite to their genotypes, none can experience complete sex reversal or produce offspring under natural conditions. Promising evidence indicates that the incomplete sex reversal is associated with cell autonomous sex identity (CASI) of avian cells, which is controlled by genetic factors. However, studies cannot clearly describe the regulatory mechanism of avian CASI and sex development at present, and these factors require further exploration. In spite of this, the abundant findings of avian sex research have provided theoretical bases for the progress of gender control technologies, which are being improved through interdisciplinary co-operation and will ultimately be employed in poultry production. In this review, we provide an overview of avian sex determination and differentiation and comprehensively summarize the research progress on sex reversal in birds, especially chickens. Importantly, we describe key issues faced by applying gender control systems in poultry production and chronologically summarize the development of avian sex control methods. In conclusion, this review provides unique perspectives for avian sex studies and helps scientists develop more advanced systems for sex regulation in birds.
Topics: Female; Animals; Male; Chickens; Sex Determination Processes; Gonads; Sex Differentiation; Ovary
PubMed: 37175998
DOI: 10.3390/ijms24098284 -
Cells May 2022Most cultured Japanese eels () show male sex differentiation; however, natural gonadal sex differentiation has not been evaluated. In this study, this process was...
Most cultured Japanese eels () show male sex differentiation; however, natural gonadal sex differentiation has not been evaluated. In this study, this process was characterized in wild eels. Differentiated ovaries and testes were observed after the eels grew to 320 and 300 mm in total length, respectively. The youngest ovary and testis appeared at 3 and 4 years old, respectively; however, undifferentiated gonads were found up to 7 years, suggesting that sex differentiation was triggered by growth rather than aging. , , and were highly expressed in the testes, whereas , , , and were highly expressed in the ovaries. The expression of and did not differ significantly between the testis and ovary. In the ovaries, the and levels were highest in the early stages, suggesting that their function is limited to early ovarian differentiation. The , and levels tended to increase in the later stages, suggesting that they function after the initiation of ovarian differentiation. In undifferentiated gonads, dimorphic gene expression was not observed, suggesting that the molecular sex differentiation phase is short and difficult to detect. These findings provide the first demonstration of the whole course of natural gonadal sex differentiation in eels at molecular and morphological levels.
Topics: Anguilla; Animals; Female; Gonads; Male; Ovary; Sex Differentiation; Testis
PubMed: 35563858
DOI: 10.3390/cells11091554 -
Sexual Development : Genetics,... 2016Sexual differentiation in birds is controlled genetically as in mammals, although the sex chromosomes are different. Males have a ZZ sex chromosome constitution, while... (Review)
Review
Sexual differentiation in birds is controlled genetically as in mammals, although the sex chromosomes are different. Males have a ZZ sex chromosome constitution, while females are ZW. Gene(s) on the sex chromosomes must initiate gonadal sex differentiation during embryonic life, inducing paired testes in ZZ individuals and unilateral ovaries in ZW individuals. The traditional view of avian sexual differentiation aligns with that expounded for other vertebrates; upon sexual differentiation, the gonads secrete sex steroid hormones that masculinise or feminise the rest of the body. However, recent studies on naturally occurring or experimentally induced avian sex reversal suggest a significant role for direct genetic factors, in addition to sex hormones, in regulating sexual differentiation of the soma in birds. This review will provide an overview of sex determination in birds and both naturally and experimentally induced sex reversal, with emphasis on the key role of oestrogen. We then consider how recent studies on sex reversal and gynandromorphic birds (half male:half female) are shaping our understanding of sexual differentiation in avians and in vertebrates more broadly. Current evidence shows that sexual differentiation in birds is a mix of direct genetic and hormonal mechanisms. Perturbation of either of these components may lead to sex reversal.
Topics: Animals; Birds; Disorders of Sex Development; Female; Gonads; Male; Ovary; Sex Determination Processes; Sex Differentiation; Testis
PubMed: 27529790
DOI: 10.1159/000448365 -
Ecotoxicology (London, England) 2003This mini-review focuses on sexual differentiation of the reproductive organs and the brain in birds and the effects of endocrine modulators on these processes. Sex... (Review)
Review
This mini-review focuses on sexual differentiation of the reproductive organs and the brain in birds and the effects of endocrine modulators on these processes. Sex determination in birds is genetically controlled, but the genetic events implicated are largely unknown. Female birds have one Z and one W sex chromosome, while males have two Z sex chromosomes. It is not clear whether it is the presence of the W chromosome in females, the double dose of the Z chromosome in males vis-à-vis females, or both of these characteristics that are crucial for the determination of sex in birds. Oestradiol directs sexual differentiation in birds during critical periods of development. Consequently, exogenous compounds that interfere with the endogenous oestrogen balance can disrupt sexual differentiation of the reproductive organs and the brain. Therefore, sexual differentiation in birds provides a good model for studying the effects of endocrine modulators at various biological levels from gene expression to behaviour. Some compounds known to be present in the environment can alter endocrine function and have adverse effects when administered during development, resulting in alterations in gonads, accessory sexual organs, and behaviour. Data reviewed in this paper are mostly from laboratory studies on endocrine modulators with oestrogenic activity, whereas evidence for adverse effects of pollutants on sexual differentiation in avian wildlife is scarce.
Topics: Animals; Birds; Endocrine System; Estrogens; Female; Male; Sex Chromosomes; Sex Differentiation; Xenobiotics
PubMed: 12739875
DOI: 10.1023/a:1022567113596 -
WIREs Mechanisms of Disease 2024In multicellular organisms, sexed gonads have evolved that facilitate release of sperm versus eggs, and bilaterian animals purposefully combine their gametes via mating... (Review)
Review
In multicellular organisms, sexed gonads have evolved that facilitate release of sperm versus eggs, and bilaterian animals purposefully combine their gametes via mating behaviors. Distinct neural circuits have evolved that control these physically different mating events for animals producing eggs from ovaries versus sperm from testis. In this review, we will describe the developmental mechanisms that sexually differentiate neural circuits across three major clades of bilaterian animals-Ecdysozoa, Deuterosomia, and Lophotrochozoa. While many of the mechanisms inducing somatic and neuronal sex differentiation across these diverse organisms are clade-specific rather than evolutionarily conserved, we develop a common framework for considering the developmental logic of these events and the types of neuronal differences that produce sex-differentiated behaviors. This article is categorized under: Congenital Diseases > Stem Cells and Development Neurological Diseases > Stem Cells and Development.
Topics: Male; Animals; Sex Differentiation; Semen; Reproduction; Germ Cells; Spermatozoa
PubMed: 38185860
DOI: 10.1002/wsbm.1636 -
Sexual Development : Genetics,... 2016Foxl2 is a member of the large family of Forkhead Box (Fox) domain transcription factors. It emerged during the last 15 years as a key player in ovarian differentiation... (Review)
Review
Foxl2 is a member of the large family of Forkhead Box (Fox) domain transcription factors. It emerged during the last 15 years as a key player in ovarian differentiation and oogenesis in vertebrates and especially mammals. This review focuses on Foxl2 genes in light of recent findings on their evolution, expression, and implication in sex differentiation in animals in general. Homologs of Foxl2 and its paralog Foxl3 are found in all metazoans, but their gene evolution is complex, with multiple gains and losses following successive whole genome duplication events in vertebrates. This review aims to decipher the evolutionary forces that drove Foxl2/3 gene specialization through sub- and neo-functionalization during evolution. Expression data in metazoans suggests that Foxl2/3 progressively acquired a role in both somatic and germ cell gonad differentiation and that a certain degree of sub-functionalization occurred after its duplication in vertebrates. This generated a scenario where Foxl2 is predominantly expressed in ovarian somatic cells and Foxl3 in male germ cells. To support this hypothesis, we provide original results showing that in the pea aphid (insects) foxl2/3 is predominantly expressed in sexual females and showing that in bovine ovaries FOXL2 is specifically expressed in granulosa cells. Overall, current results suggest that Foxl2 and Foxl3 are evolutionarily conserved players involved in somatic and germinal differentiation of gonadal sex.
Topics: Animals; Evolution, Molecular; Female; Forkhead Box Protein L2; Forkhead Transcription Factors; Germ Cells; Gonads; Humans; Male; Phylogeny; Sex Differentiation; Vertebrates
PubMed: 27441599
DOI: 10.1159/000447611 -
Medicina (Kaunas, Lithuania) 2005The complex mechanisms are responsible for male sex determination and differentiation. The steps of formation of the testes are dependent on a series of Y-linked,... (Review)
Review
The complex mechanisms are responsible for male sex determination and differentiation. The steps of formation of the testes are dependent on a series of Y-linked, X-linked and autosomal genes actions and interactions. After formation of testes the gonads secrete hormones, which are essential for the formation of the male genitalia. Hormones are transcription regulators, which function by specific receptors. Ambiguous genitalia are result of disruption of genetic interaction. This review describes the mechanisms, which lead to differentiation of male sex and ways by which the determination and differentiation may be interrupted by naturally occurring mutations, causing different syndromes and diseases.
Topics: Adolescent; Adult; Androgens; Chromosome Deletion; Disorders of Sex Development; Female; Gestational Age; Humans; Infant, Newborn; Male; Mutation; Pregnancy; Sex Determination Processes; Sex Differentiation; Testicular Hormones; Transcription Factors; Transcription, Genetic; Virilism
PubMed: 16160410
DOI: No ID Found -
Journal of Endocrinological... 2003In humans, like as in other mammals, the gonads, the internal genital ducts, and the external genital structures all develop from bipotential embryologic tissues. Male... (Review)
Review
In humans, like as in other mammals, the gonads, the internal genital ducts, and the external genital structures all develop from bipotential embryologic tissues. Male or female phenotype develops through a cascade of processes which initiate with sex determination and follow with sex differentiation. The karyotype (46, XY or 46, XX) of the embryo (genetic sex) determines whether primordial gonad differentiates into a testis or an ovary, respectively (gonadal differentiation). A Y-related gene, SRY, acts as a switch signal for testis differentiation. Testis development process involves several steps controlled by other non-OY-linked genes, such as Wilms tumor gene 1 (WT1), EMX2, LIM1, steroidogenic factor 1(SF-1), SRY box-related gene 9 (SOX9). Since other genes, such as Wnt-4 and DAX-1, are necessary for the initiation of female pathway in sex determination, female development cannot be considered a default process. Hormonal production of differentiated gonads is relevant for differentiation of the internal and external genitalia during fetal life, and for the development of secondary sex characteristics at puberty. Antimullerian hormone (AMH) secreted by Sertoli cells inhibits the development of female internal genitalia (tube, uterus, upper part of vagina); testosterone secreted by Leydig cells induces stabilization of wolffian ducts and development of internal male genitalia. Differentiation of external male genitalia requires the transformation of testosterone to dihydrotestosterone by 5alpha reductase type 2 expressed in genital skin and urogenital sinus. The effects of androgens occur in presence of functional androgen receptor (AR) protein. Mutations of genes coding for steroidogenic enzymes, AMH, AMH receptor, AR and 5alpha reductase are all associated with impairment of sex differentiation and result in genital ambiguity.
Topics: Embryonic and Fetal Development; Genitalia; Humans; Sex Determination Processes; Sex Differentiation
PubMed: 12834017
DOI: No ID Found