2005, Number 3
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Vet Mex 2005; 36 (3)
Sexual differentiation in the central nervous system
Herrera GH, Vergara OM Rosado-García A , Rosales TAM
Language: English/Spanish
References: 136
Page: 339-360
PDF size: 667.46 Kb.
ABSTRACT
Reproductive expression in most vertebrates depends on the stereotypical expression of each individual’s own sex conduct and this requires a series of physiological events that jointly integrate the sensorial and hormonal information. In the brain of males and females there are important anatomical and functional differences, for example, in the male rat the sexual dimorphic nucleus of the preoptic area (SDN-POA) is six times larger than in the female, while in the ventromedial and arcuate nucleus, synaptic connections are more abundant in the female than in males. From the initial studies, precursors of the present concept of sexual differentiation in the brain, it is suggested that in this process, besides the genetic sex, the hormonal environment that surrounds the neuronal tissue is also fundamental. In this sense, the gonads have a crucial role, since the secretion of the steroid hormones in a specific phase of the development of the central nervous system (CNS), called “critical period” is capable of causing morphological, anatomical, biochemical and physiological changes that give rise to permanent modifications and the establishment of sexually dimorphic structures. In domestic and laboratory mammals, as well as in other species, estradiol is a hormone that directs or causes sexual differentiation in the CNS, through mechanisms such as neurogenesis, apoptosis and differentiation or functionality of cells that are involved. Even though molecular techniques that are applied today in the biology sciences have greatly advanced, there are still many unknowns to elucidate in the scientific knowledge relative to this process in the reproductive area,. In this work, the present panorama knowledge of sexual differentiation of the CNS is presented in order to motivate or promote interest in the study of this topic and its possible application in animal production. The brain areas or zones that are considered dimorphic are described and we present a thorough review, although synthesized, of the effect that estradiol has on the modification of gene expression patterns that control the genesis of neurons and synapsis, or the apoptosis processes of the CNS and how this determines the amount of neurons that form the sexual dimorphic nuclei. Also, we present in chronological order the knowledge that was being developed on this topic, accordingly with the methodological tools that were available.
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