Patterns Of Sexual Development Research Articles

Conservation and diversity in expression of candidate genes regulating socially-induced female-male sex change in wrasses.

Fishes exhibit remarkably diverse, and plastic, patterns of sexual development, most striking of which is sequential hermaphroditism, where individuals readily reverse sex in adulthood. How this stunning example of phenotypic plasticity is controlled at a genetic level remains poorly understood. Several genes have been implicated in regulating sex change, yet the degree to which a conserved genetic machinery orchestrates this process has not yet been addressed. Using captive and in-the-field social manipulations to initiate sex change, combined with a comparative qPCR approach, we compared expression patterns of four candidate regulatory genes among three species of wrasses (Labridae)—a large and diverse teleost family where female-to-male sex change is pervasive, socially-cued, and likely ancestral. Expression in brain and gonadal tissues were compared among the iconic tropical bluehead wrasse (Thalassoma bifasciatum) and the temperate spotty (Notolabrus celidotus) and kyusen (Parajulus poecilepterus) wrasses. In all three species, gonadal sex change was preceded by downregulation of cyp19a1a (encoding gonadal aromatase that converts androgens to oestrogens) and accompanied by upregulation of amh (encoding anti-müllerian hormone that primarily regulates male germ cell development), and these genes may act concurrently to orchestrate ovary-testis transformation. In the brain, our data argue against a role for brain aromatase (cyp19a1b) in initiating behavioural sex change, as its expression trailed behavioural changes. However, we find that isotocin (it, that regulates teleost socio-sexual behaviours) expression correlated with dominant male-specific behaviours in the bluehead wrasse, suggesting it upregulation mediates the rapid behavioural sex change characteristic of blueheads and other tropical wrasses. However, it expression was not sex-biased in temperate spotty and kyusen wrasses, where sex change is more protracted and social groups may be less tightly-structured. Together, these findings suggest that while key components of the molecular machinery controlling gonadal sex change are phylogenetically conserved among wrasses, neural pathways governing behavioural sex change may be more variable.

Sexual development and demography of the rock hind Epinephelus adscensionis, a protogynous grouper, in the south-west Atlantic

This study reports on the pattern of sexual development and demography of Epinephelus adscensionis sampled on the north-east coast of Brazil. The species is a protogynous hermaphrodite, with males (26–44-cm total length, TL) transitioning from mature females (20–33cm TL). This species presented multiple spawning, with peaks in the gonadosomatic index indicating that the spawning period of the rock hind occurred along 3 months per year, where for 2008 was between August and October, and for 2009 was between July and September. Age was determined from otoliths and periodicity was validated from captive fish treated with tetracycline. The resulting von Bertalanffy growth parameters were as follows: theoretical maximum length (L∞) 34.82cm TL, growth coefficient (k) 0.26 and theoretical age at L=0 (t0) 0.86years. The size and age at sexual maturity for females were 20cm TL and 4 years. The total rate of mortality was 0.28year–1. Older fish were males and had a maximum longevity of 15 years. This species is an important resource for local communities, but is also currently caught by trap fisheries, which have been expanding in recent decades in response to demands of export markets. Lack of monitoring and management of these and other reef fisheries in north-east Brazil makes fishing sustainability uncertain.

Sexual Definition: is there a pattern in the sexuality of fish? A Revision

The fish are found in the most diverse aquatic habitats, ranging from high altitudes the depressions far below sea level, which reflects a wide range of existing species. This condition is due to diversity genomics be enriched by the fusion of the gametes in the training of individuals and in sex determination. Of genetic recombinations, during the processes of cell division and reproductive strategies, which result in a broad adaptive plasticity, both biological and ecological. All this becomes possible through the playback, where also if there is a great diversity of forms, even if there is a pattern of sexual development as well defined as male or female in the majority of species, constituting the gonochorists, and a small fraction formed by types of reproductive unisexual sessile and hermaphrodites. The explanation of this diversity has as a basis the property of retaining the dual sexual potentiality of primordial germ cells, found in different stages in gonadogenesis, and by their ability to differentiate during the reproductive life, a biological base kept by teleosts, constituting all plasticity. For this reason, it was possible to observe species that show great stability and other very labile to change the sex throughout their life. These different forms of reproduction has its origin in the great variety of mechanisms responsible for both sex determination as to formation of patterns of sexual differentiation, which include a genetic basis, with monogenic and polygenic systems, and the influence of different environmental factors, mainly temperature and social interactions. Although the mechanisms of sex determination and differentiation are conserved in mammals and birds, in fish seem to be very unstable. This suggests that, in evolutionary terms, an accumulation of evidence of participatory process in favor of a unification of strategies that emphasize the genetic factors and the environment. In particular, it seems that the environmental factors govern the force responsible for sexual development and by developments in all levels, with the selection and genetic drift having been responsible for establishing a standard capable of characterizing the current sexual determination. Thus, the proposal would be: in what way or in what level these factors contribute to driving the evolutionary process, independent of any context and in a way wholly holistic .

Differences in Dental and Bone Maturation in Regions With or Without Hemihypertrophy in Two Patients with Russell-Silver Syndrome

Hemihypertrophy (hemihyperplasia) is defined as asymmetric body overgrowth of one or more body parts. Hemihypertrophy can be isolated or be part of well-defined syndromes, such as Russell-Silver syndrome (RSS). RSS is characterized by severe intrauterine growth retardation, postnatal short stature, asymmetry of the face, body, and limbs, short and incurved fifth fingers, broad forehead, pointed small triangular shaped face, girdle nose, normal psychomotor development, variations in the pattern of sexual development, and dental and oral abnormalities. The aim of this study was to determine whether or not there was any difference in the maturity of bone in left and right hand-wrist radiographs and dental development in the right and left jaws of two patients with RSS. In addition, the clinical features of the syndrome are discussed.

Oxandrolone in constitutional delay of growth: analysis of the growth patterns up to final stature.

In order to evaluate the effects of low-dosage, 6-12 months course of oxandrolone treatment in constitutional delay of growth, we compared the growth responses on treatment, the pattern of sexual development and pubertal growth events, up to final stature of 11 prepubertal boys, aged 10.6-14.1 yr, with those of 11 prepubertal, age-matched untreated controls. Treatment caused a significant increase of height velocity, from 4 to 9 cm/yr, and a significant acceleration of bone maturation, without affecting the timing of onset of puberty, the progression of sexual development or the onset of pubertal growth spurt. On the other hand, oxandrolone induced an earlier skeletal growth arrest but did not affect the expected final height. Treated boys showed an adult stature not significantly different from that of control subjects. Our data suggest that 6 months-1 year, low dosage oxandrolone treatment in constitutionally delayed growth has no significant effect on the pattern of pubertal growth, nor on the rate of sexual maturation or on final height.

A study of sexual development in ram lambs

ABSTRACTTwo experiments were designed to study the effect of rearing method, female company, and repeated libido and semen tests on the pattern of sexual development of ram lambs. Four artificial rearing treatments (AR) were compared with natural rearing (NR) in one experiment and four artificial compared with three natural rearing treatments in a second experiment. Lambs on AR treatments in both experiments, as well as naturally reared lambs in the second experiment, were reared with or without females either before and/or after weaning. Half the lambs in the second experiment were libido and semen tested, and their mean plasma testosterone level was also measured, while the rest were only tested at the end of the experiment. The effect of method of rearing and female company on body growth, testes diameter, libido and semen quality were also investigated.A close relationship was found between body weight and sexual characteristics (for example, testis diameter, semen traits, libido, testosterone level and age at the onset of sexual maturity). NR resulted in faster growth than AR but was not appreciably different from early weaned-naturally reared treatments. It was also observed that mating performance improved steadily with advancement in age and increase in body weight. The onset of sexual maturity was attained at a minimum of 23 kg body weight and a minimum of 198 days of age. However, the heavier the lamb when sexually mature, the better its mating performance.Previous libido tests of ram lambs improved their subsequent mating performance, but had no effect on semen quality. However, libido tests did not improve the performance of those ram lambs which did not exhibit initial libido.It is suggested that early weaning at 2 months of age could be a suitable system for ram lambs weaned off their mothers for breeding purposes. These lambs should be reared as an all-male group but libido tested at monthly intervals commencing at 3 months of age. The criteria for selecting these lambs at an earlier age should be body weight and testis diameter.

THE SILVER SYNDROME: CONGENITAL ASYMMETRY, SHORT STATURE AND VARIATIONS IN SEXUAL DEVELOPMENT

THE SILVER SYNDROME: CONGENITAL ASYMMETRY, SHORT STATURE AND VARIATIONS IN SEXUAL DEVELOPMENT ROENTGEN FEATURESJOHN E. MOSELEY, M.D., RALPH E. MOLOSHOK, M.D. and ROBERT H. FREIBERGER, M.D.Audio Available | Share

Der hormonale einfluss des Gehirns auf die sexuelle Entwicklung bei dem polychaeten Platynereis dumerilii

In Platynereis dumerilii a cerebral incretion controls sexual development, comprising simultaneous maturation of the germ cells and epitokous metamorphosis to the so-called heteronereis stage. Only results obtained from females are reported in this summary. In stages with oocytes ranging in size from 80 to 140 μ, removal of either the brain or of the prostomium may accelerate normal maturation slightly. In worms with smaller oocytes the same operations prevent or at least impair sexual development. However, animals decapitated in these stages readily mature upon implantation of isolated prostomia into their coelom; this applies even to small fragments comprising a few segments of such animals. The time needed for maturation depends mainly on the sexual state of the donor whereas that of the host appears to be of little importance. Thus, sexual development takes much longer with a prostomial implant from a juvenile than with one from a nearly mature adult animal. Larval heads may induce fragments of juvenile females to mature within an extremely short time; hence there is not a specific “epitoke hormone”. It is more likely that the brain produces the same type of incretion throughout the whole span of life; the qualitatively different effects of this incretion must be determined only by its relative concentration; this is high in the presence of juvenile prostomia, and low after implantation of prostomia from mature animals or from tiny larval heads. Thus sexual development is envisaged as being controlled under normal conditions by a gradually decreasing hormonal titer, different processes being assigned to each concentration. This assumption would also account for the fact that germ cell maturation and metamorphosis usually take place simultaneously, although in experiments they may occur independently of each other. Graded UV-irradiation of the brain of intact animals with germ cells results in precocious maturation. The average span of time between irradiation and maturation equals that between decrease of photoperiod and maturation in previous experiments. This supports the view that the lunar swarming periodicity observed under natural conditions is due to photoperiodic suppression of cerebral endocrine activity. Amputation of a number of posterior segments stimulates the production of the cerebral incretions that are necessary for regeneration of the lost segments. Since the same operation effects a retardation of sexual development, it may be inferred from these experiments as well as from those quoted above that rate and pattern of sexual development are determined exclusively by the intensity of cerebral incretory processes, a high titer of hormone inhibiting, and a low titer facilitating, sexual development. The effects of implanted prostomium fragments obtained by transverse section agree well with previous histological results, which indicate a neurosecretory origin of the prostomial incretion.

Current concepts of sexual abnormalities.

The gonads, germ cells, and internal and external genital systems are bipotential early in fetal life. Failure to develop in a manner which corresponds to the genetic sex usually results in gonadal or genital abnormalities. Recent progress has clarified the patterns of sexual development, and it is possible to diagnose and treat most of these abnormalities early in life.Turner's syndrome, true hermaphroditism, Klinefelter syndrome, and pseudohermaphroditism are discussed in relation to normal sexual development, which is categorically divided into six phases.

PRECOCIOUS GROWTH OF SEXUAL HAIR WITHOUT OTHER SECONDARY SEXUAL DEVELOPMENT; "PREMATURE PUBARCHE," A CONSTITUTIONAL VARIATION OF ADOLESCENCE

GROWTH of sexual hair in a young child suggests the possibility that adrenal tumor or hyperplasia may be causing virilization or that true sexual precocity may be beginning. However, neither of these relatively serious conditions may exist. Approximately 10 years ago workers in the Endocrine Clinic of the Harriet Lane Home became aware of the fact that sexual hair may appear in early life long before there is any other secondary sexual development dependent upon either androgen or estrogen. Although this syndrome has been referred to briefly in textbooks as "precocious adrenarche" and "premature pubarche," no detailed studies of a series of cases have been recorded. The present report is based on a study of 29 children who developed sexual hair before the age of 8 years. It was possible to follow a number of these patients long enough to demonstrate that the condition is a benign variation in the pattern of sexual development and is followed later by normal adolescence. It seems important to bring the findings to the attention of pediatricians who may not be familiar with the syndrome and to discuss its differential diagnosis and probable etiology. Methods Urinary 17-ketosteroids (17-KS) were determined by a modification of the method of Callow, Callow and Emmons previously described, urinary estrogens were measured as the "fluorogenic phenols" by the method of Jailer. Vaginal smears stained by the method of Shorr were interpreted as described elsewhere. The "bone age" was based on the average epiphysial development at all the joints. Clinical and Laboratory Findings