Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Sexual Development”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,243 records · Page 69Linked to original sources
PubMed2001

Arrested development of secondary sexual adornments in subordinate adult male mandrills (Mandrillus sphinx).

Previous studies of semifree-ranging mandrills identified two morphological and social variants of the adult male, based on behavioral and secondary sexual characteristics. "Fatted" males are social, with highly developed sex skin coloration, large testes, high plasma testosterone levels, and fat rumps; while "nonfatted" males are peripheral or solitary, with paler sex skin, smaller testes, lower plasma testosterone, and slimmer rumps. We present a detailed study of morphology and group association for 10 adult male mandrills, living in two semifree-ranging groups in Gabon, in order to relate differences between males to dominance rank. The results show that rather than existing as two distinct morphotypes, male mandrills represent a continuous spectrum of possibilities between social males with fully developed secondary sexual characteristics, and solitary males with muted secondary sexual characteristics. Alpha males (N = 2) had the highest testosterone levels, the most colorful sex skin, and the most active sternal glands, and were the only males to spend 100% of their time with the social group. Rank relationships between nonalpha males (N = 8) were not always clear, but all subordinate males had lower testosterone levels and less development of the secondary sexual adornments, and were less group-associated than alpha males. These findings suggest that only alpha males have sufficient testosterone to develop full secondary sexual characteristics, and we propose possible socioendocrine mechanisms underlying the suppression of testosterone and secondary sexual development in subordinate adults. We discuss differences in secondary sexual development in relation to reproductive strategies, and discuss the evolution of alternative reproductive morphs in primates.

Animals↗
PubMed2005

Gene expression during sex determination reveals a robust female genetic program at the onset of ovarian development.

The primary event in mammalian sexual development is the differentiation of the bipotential gonads into either testes or ovaries. Our understanding of the molecular pathways specifying gonadal differentiation is still incomplete. To identify the initial molecular changes accompanying gonadal differentiation in mice, we have performed a large-scale transcriptional analysis of XX and XY Sf1-positive gonadal cells during sex determination. In both male and female genital ridges, a robust genetic program is initiated pre-dating the first morphological changes of the differentiating gonads. Between E10.5 and E13.5, 2306 genes were expressed in a sex-specific manner in the somatic compartment of the gonads; 1223 were overexpressed in XX embryos and 1083 in XY embryos. Although sexually dimorphic genes were scattered throughout the mouse genome, we identified chromosomal regions hosting clusters of genes displaying similar expression profiles. The cyclin-dependent kinase inhibitors Cdkn1a and Cdkn1c are overexpressed in XX gonads at E11.5 and E12.5, suggesting that the increased proliferation of XY gonads relative to XX gonads may result from the overexpression of cell cycle inhibitors in the developing ovaries. These studies define the major characteristics of testicular and ovarian transcriptional programs and reveal the richness of signaling processes in differentiation of the bipotential gonads into testes and ovaries.

Animals↗
PubMed1978

Endocrine regulation of reproductive development and function in the male.

Sexual development is an ordered process that begins at the moment of fertilization and terminates with the production and transfer of viable gametes. The formation of the male gonad depends upon genes located on both sex chromosomes and autosomes. Differentiation and growth of the male reproductive system is directed by the fetal testis through the production of a putative peptide which causes the regression of the Mullerian ducts and the secretion of testosterone which virilizes the Wolffian duct and thereby directs the differentiation of the internal accessory structures of reproduction. A third hormone, dihydrotestosterone, is synthesized intracellularly from testosterone within the urogenital sinus and tubercle. The action of this hormone controls the formation of the prostate and the external genitalia characteristic of the male phenotype. The postnatal growth of the testis and accessory sex tissues follows a characteristic curvilinear pattern with the most prominent increments coincident with the onset in testosterone production. Spermatogonial differentiation may proceed in the absence of hypophyseal or gonadal hormones but the respective maturation divisions of primary and secondary spermatocytes and the completion of spermiogenesis are clearly dependent upon testicular steroids produced under the influence of LH. Germ cells differentiate in a unique environment created, in part, by the blood testis barrier which arises as a result of tight-junctional complexes formed between adjacent Sertoli cells. Sertoli cells actively secrete fluids and export an androgen binding protein under the influence of androgens and FSH. Maintenance of spermatogenesis depends on high intratubular concentrations of testosterone, provided in part by the steroidogenic actions of LH on the Leydig cell and, in part, by the production of androgen binding protein by the Sertoli cell. Thus, both gonadotropins act in concert to maintain germ cell production. Selective removal of either LH or FSH curtails sperm production but testosterone supplementation, in adequate amounts, allows spermatogenesis to proceed in the absence of the pituitary gland.

Androgens↗
PubMed2005

The complex interplay between mosquito positive and negative regulators of Plasmodium development.

The malaria parasite, Plasmodium, requires sexual development in the mosquito before it can be transmitted to the vertebrate host. Mosquito genes are able to substantially modulate this process, which can result in major decreases in parasite numbers. Even in susceptible mosquitoes, haemolymph proteins implicated in systemic immune reactions, together with local epithelial responses, cause lysis of more than 80% of the ookinetes that cross the mosquito midgut. In a refractory mosquito strain, immune responses lead to melanisation of virtually all parasites. Conversely, certain mosquito genes have an opposite effect: they are used by the parasite to evade defence reactions. Detailed understanding of the interplay between positive and negative regulators of parasite development could lead to the generation of novel approaches for malaria control through the vector.

Animals↗
PubMed1995

Animals models for the development of human sexuality: a critical evaluation.

Biological explanations of human homosexuality build upon a theoretical framework developed from the study of animals, especially that of rodents. Researchers have constructed a physiological model to explain the origin and development of "masculine" and "feminine" behavior. According to this model hormones acting at critical stages in early development organize cells in key areas of the brain. After puberty these hormonally organized brain regions are purportedly capable of activation by post-pubertally produced circulating hormones. This model of sexual development, called the organizational-activational (O/A) model, has framed research on sexual behavior in animals and animal-based account of human behavior for more than 30 years. However, evidence from a variety of sources has slowly accumulated, requiring modification after modification of the original premise. Continuing to use the organizational-activational model now interferes with the acquisition of new knowledge. I sketch the outlines of an alternative bio-social program for research on the development of sexual behavior in animals.

Adolescent↗
PubMed1988

Self-concept, sexual knowledge and attitudes, and parental support in the sexual adjustment of women with early- and late-onset physical disability.

Three groups of college women were compared on the following dimensions: sexual experiences, sexual satisfaction, self-concept, sexual attitudes and knowledge, and parental support for sexual development. Groups were composed of women with late-onset physical disability, early-onset physical disability, and no disability. Measures utilized included an extension of the Sexual Interaction Inventory, the Tennessee Self-Concept Inventory, the Sexual Knowledge and Attitude Test, and questionnaires developed for this study. The early-onset group reported fewer current sexual experiences than did the nondisabled group. The early-onset group was dissatisfied with the frequency of sexual behavior to a greater degree than the nondisabled group. Also, both disabled groups believed that they could enjoy sexual experiences more than they did at present in contrast to the nondisabled group. There were no group differences for self-concept, though several aspects of self-concept contributed significantly to sexual adjustment for the disabled groups. No group differences were found for sexual knowledge and attitudes or parental support for sexual development, nor did these variables relate to sexual adjustment. Group differences in sexual adjustment are discussed in terms of functional, emotional, and social implications. Recommendations for further research include following the social development of women with late-onset conditions, comparing the social skills and cognitions of the two disabled groups, and assessing men who have established intimate relationships with disabled women.

Adaptation, Psychological↗
PubMed1996

Sexually transmitted diseases control in developing countries.

Sexually transmitted diseases (STDs) are a major public health problem now compounded by the advent of AIDS and HIV infection. The size of the problem represented by STDs and HIV is unknown however it is estimated that there are 333 million new cases of STD per annum and currently 15-20 million people infected worldwide with HIV. Control programmes for STDs must prevent the acquisition of STDs, their complications and sequelae and interrupt and reduce transmission. They can also reduce the incidence of HIV infection. Such programmes must place emphasis on health education, condom usage, altering health seeking behaviour and providing case management. The syndromic approach currently offers the most realistic, and cost effective, way in which to treat patients.

Adolescent↗
PubMed2003

Individual and familial influences on the onset of sexual intercourse among urban African American adolescents.

A sample of 198 African American families, living in urban poverty, participated in a longitudinal study of adolescent sexual development beginning when children were in the 4th or 5th grade. Self-reports of family conflict and pubertal development and videotaped family interaction data were collected at 2 time points approximately 2 years apart. Youths reported on sexual debut at each time point. More boys than girls reached sexual debut early. Greater levels of family conflict predicted early sexual debut. Observational data indicated more developed preadolescents with greater family conflict and less positive affect were least likely to delay debut. Changes in pubertal development and observed family conflict were associated with early debut. Possible mediating mechanisms and implications for preventive interventions are discussed.

Adolescent↗