Sexual differentiation

Sexual differentiation in mammals is linked to the composition of the sex chromosomes. In the genetic male, the sexually determining region (Sry) gene on the Y chromosome promotes the differentiation of the testis from the indifferent gonad, resulting in the production of two critical hormonal signals, testosterone and anti-Mullerian hormone (Arnold, 2004 Breedlove andHampson, 2002 Goy and McEwen, 1980 McCarthy, 1994). These hormones initiate the differentiation of the reproductive tracts and...

Sex Differences In The Rodent Vno Pathway

The rodent vomeronasal system exhibits sexual dimorphisms at multiple levels along its projection pathway. The MeA, BNST, and MPOA are all larger in the male than female, while subsequent projections to the hypothalamic nuclei, particularly those concerned with female endocrine regulation and maternal care, tend to be larger in the female (Segovia and Guillamon, 1996) (Fig. 8.5). Lesions in discrete parts of this projection pathway enhance components of female typical behavior, whereas in the...

B The VC neurons

The VC neurons are cholinergic motor neurons that have synaptic connections to the HSNs and the vm2 vulval muscles (White et al., 1986). The VCs have a more subtle effect on egg-laying behavior, acting to negatively regulate vulval muscle contraction. This function is mediated by their release of acetylcholine, which may inhibit the HSN-mediated stimulation of vulval muscle contraction (Bany et al., 2003). Rather than sex-specific cell death, it is a cell fate change that underlies the sexually...

The Genetics Of Sexual Orientation

Although there is no convincing evidence linking differences in sexual orientation to variations in prenatal androgens, there is abundant evidence for a strong genetic component. Family studies (Bailey and Bell, 1993 Bailey and Benishay, 1993 Bailey and Pillard, 1991 Bailey et al., 1995, 1999 Pattatucci and Hamer, 1995 Pillard, 1990 Pillard and Weinrich, 1986) showed an increased rate of homosexuality in siblings of gays and lesbians and in the maternal uncles of gay men (a median rate of 9 for...

The Central Dogma Of Sexual Differentiation

In the late 1940s, the classic gonad-transfer experiments of Alfred Jost led to the development of the central dogma of sexual differentiation in mammals and birds Jost, 1947, 1970 . According to this view, sexual dimorphisms of somatic tissues are dependent primarily on testicular secretions from the developing fetus. The presence of testes induces male development through the actions of two secreted testicular hormones, Mullerian inhibiting substance and testosterone. Absence of testicular...

Cellular Basis Of fru Functions In Male Courtship Behavior

In neurobiology, it is critical to determine the neural circuit underlying respective behavior. It is a demanding issue to describe neural connections formed by fru-expressing neurons to illustrate the entire network that determines male courtship behavior. To this end, efforts have been made to identify individual neurons that express Fru Billeter and Goodwin, 2004 Manoli et al., 2005 Stockinger et al., 2005 . To identify fru-expressing neurons, it is crucial to obtain reporter strains that...

Introduction

Karlson and Luscher 1959 defined pheromones as substances secreted to the outside of an individual and received by a second individual of the same species in which they release a specific reaction, for example, a definite behavior or developmental process. This new term was created based on identification of a volatile sex attractant, bombykol, that is released by the female silk moth Bombyx mori and elicits the full sexual behavior of male moths Butenandt et al., 1959 . In contrast to such...

BThe CA and CP motor neurons

The only male-specific cells of the ventral nerve cord are the CA and CP motor neurons. Lineally, the CAs and CPs are analogous to the hermaphrodite VC neurons, as they arise from the division of the Pn.aap cells, which either become VC neurons or die in hermaphrodites Fig. 1.3 . In males, the Pn.aap cells do not die this may be the default hermaphrodite fate , but instead remain undifferentiated until they divide during L3 to give rise to one CA and one CP. As discussed above, it is possible...

Daisuke Yamamoto

Division of Neurogenetics, Graduate School of Life Sciences Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai Miyagi 980-8578, Japan I. Hypothesis on the Master Control Gene for Behavior II. Discovery of fru Mutants and Their Phenotypic Characteristics III. Molecular Biology of fru Locus IV. Cellular Basis of fru Functions in Male Courtship Behavior V. Conclusions Acknowledgments References fruitless fru , originally identified with its mutant conferring male homosexuality, is a neural sex...

Genomic Imprinting Coadaptive Evolution Of Brain And Placenta

The placental trophoblast is an extraordinary tissue capable of producing a vast range of endocrine secretions, which enable the fetus to regulate its own destiny. Most of these placental hormones function by acting on maternal receptors, an interaction that has required genomic coadaptation between mother and fetus. Hence, the functioning of two genomes maternal and fetal as part of a single phenotype pregnant mother provides a template for coadaptive selection pressures to operate. Early...

Maternal effects on HPG function and mating behavior

In an effort to establish the regional specificity we examined ERa expression in multiple brain regions. To our surprise, we found that ERa mRNA expression is significantly increased in the ventromedial nucleus of the hypothalamus VMNh in the offspring of Low LG mothers. Further studies revealed a significant increase in the AVPV region of the female offspring of Low LG mothers. Estrogen acts through ERs in the AVPV to regulate GnRH with downstream effects on pulsitile LH and ovarian hormone...

References

A. 1992 . Sexual orientation and the size of the anterior commissure in the human brain. Proc. Natl. Acad. Sci. USA 89, 7199-7202. Arai, Y., and Matsumoto, A. 1978 . Synapse formation of the hypothalamic arcuate nucleus during post-natal development in the female rat and its modification by neonatal estrogen treatment. Psychoneuroendocrinology 3 1 , 31-45. Arnold, A. P. 1996 . Genetically triggered sexual differentiation of brain and behavior. Horm. Behav. 30 4 ,...

Steroid sensitivity of avian vocal control networks

Comparative studies of the distribution of estrogen and androgen receptors expressing cells in vertebrate brains have shown that the brain regions, which typically contain such cells, are evolutionarily conserved e.g., hypothalamic-preoptic areas or are linked to taxa-specific sexual behaviors Kim et al., 1978 Pfaff, 1980 . Vocal control areas are an example of the latter Bernard et al., 1999 Gahr, 2000 Gahr et al., 1993 Metzdorf et al., 1999 . The classical androgen and estrogen receptors are...

The search for a VNO ligand

Initially, it was thought that pheromonal information is processed by the VNO system and odorants by the main olfactory system. Increasing evidence, however, has suggested that both systems can detect pheromones Baxi et al., 2006 Spehr et al., 2006b Stowers and Marton, 2005 . For example, imaging and electrophysiological techniques have revealed that the volatile urinary pheromones implicated in various intraspecies responses activate both olfactory and vomer-onasal sensory neurons...

The Endocrinology Of Birds Vocalization

Obligate sex-specific vocalizations are either due to brain-intrinsic genetic mechanisms or result from irreversible ontogenetic action of testosterone and its androgenic and estrogenic metabolites. Facultative sex-specific vocalizations might be due to the action of elevated levels of gonadal steroids that could occur repeatedly at various time-windows throughout life. Although there is very good experimental evidence for sex steroids affecting sex-specific vocalizations as in the case of...

Genomic organization of the ESP family

ESP1 turned out to be a member of a large multigene family that was unknown when we reported it in October 2005 Kimoto et al., 2005 . This novel family has been named the ESP family Kimoto et al., 2005 . In October 2005, the ESP family included 24 members, but by May 2006, the number had increased to 38 because there had been many gaps in the region of the ESP gene cluster Fig. 6.4 Kimoto et al., 2006 . Of the 38 ESP genes, 15 are expressed in an exocrine gland around the face area, supporting...

Elizabeth A D Hammock

Department of Pharmacology, Vanderbilt Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee 37232 II. Oxytocin and Pair Bonding in Voles III. Vasopressin and Pair Bonding in Voles C. V1aR in the ventral pallidum D. Ventral forebrain reward pathways IV. Gene Regulation in Male Species-Typical Behavior Evolutionary Tuning Knobs Copyright 2007, Elsevier Inc. All rights reserved. 0065-2660 07 35.00 DOI 10.1016 S0065-2660 07 59004-8

The anatomy of avian vocal control networks

In songbirds, neural vocal control is achieved by a chain of interconnected brain areas in the fore-, mid-, and hindbrain Nottebohm et al., 1976 Vates et al., 1997 Vu et al., 1994 Wild, 1997 Yu et al., 1996 . Vocal learning of songbirds correlates with the differentiation of forebrain vocal control areas, the robust nucleus of the arcopallium RA , lateral magnocellular nucleus of the anterior nidopallium lMAN , HVC used as proper name , medial magnocellular nucleus of the anterior nidopallium...

Sven Bocklandt and Eric Vilain

Role of SRY in Sex Determination 246 II. Male and Female Brains are Different 247 III. The Central DOGMA of Sexual Differentiation 247 IV. Sex Hormones in Brain Sexual Differentiation 248 V. Exceptions to the DOGMA 248 VI. Evidence for a Direct Role of SRY in the Brain 250 VII. Sexual Orientation is a Sexually Dimorphic Trait 251 VIII. Homosexual Brains are Different 253 IX. The Role of Prenatal Androgen Exposure on Sexual Orientation Myth or Reality 254 X. Indirect Hormonal Measures 255 XI....