378 Braz. J. vet. Res. anim. Sci., São Paulo, v. 46, n. 5, p. 378-386, 2009 Different Follicle-Stimulating Hormone (FSH) sources influence caprine preantral follicle viability and development in vitro 1 - Faculty of Veterinary Medicine, State University of Ceara, Fortaleza - CE, Brazil 2 - Laboratory of Electron Microscopy, Department of Cell Biology of University of Brasilia, Brasilia - DF, Brazil Deborah de Melo MAGALHÃES 1 Valdevane Rocha ARAUJO 1 Isabel Bezerra Lima VERDE 1 Maria Helena Tavares de MATOS 1 Renata Carvalho SILVA 2 Carolina Madeira LUCCI 2 Sônia Nair BÁO 2 Cláudio Cabral CAMPELLO 1 José Ricardo de FIGUEIREDO 1 Recebido para publicação: 06/08/2008 Aprovado para publicação: 27/08/2009 Correspondence to: Programa de Pós-Graduação em Ciências Veterinárias, Laboratório de Manipulação de Oócitos e Folículos Pré-Antrais Universidade Estadual do Ceará, Av. Paranjana, 1700, Campus do Itaperi, Fortaleza – CE – Brasil, 60740-000, fone 55.85.33101.9840, Fax:+55.85.33101.9840, dmmvet@hotmail.com Abstract The aim of this study was to evaluate the effects of pituitary (pFSH) or recombinant (rFSH) FSH on the survival and growth of caprine preantral follicles. Caprine ovarian tissues were in vitro cultured for one or seven days in Minimum Essential Medium (MEM) alone or containing 10, 50, 100 and 1000 ng/ml of pFSH or rFSH. Control tissues (non-cultured) and those cultured were processed for histological and ultrastructural studies. In addition, follicular and oocyte diameter were analysed. After seven days of culture, only 50 ng/ml of rFSH maintained the percentage of normal follicles similar to control. Moreover, 10 ng/ml of pFSH and all the concentrations of rFSH promoted primordial follicles activation. In addition, the presence of 50 ng/ml of rFSH promoted the highest follicular diameter at day seven of culture. In conclusion, 50 ng/ml of rFSH maintained the ultrastructural integrity of caprine preantral follicles, promoted primordial follicles activation and further growth of cultured follicles. Key words: Caprine. FSH. Growth. Preantral follicles. Introduction Reproductive techniques, as preantral follicles in vitro culture, are important to the achievement of a large amount of oocytes to be used in in vitro embryo production system. Some authors showed that it is possible to produce live offspring 1 or embryos of rat 2 , porcine 3 and bubalines 4 through the culture of oocytes from preantral follicles. Although the factors that regulate early folliculogenesis are not yet completely established, it is well-known that paracrine and endocrine factors are involved in this phase. Among the endocrine factors, Follicle Stimulating Hormone (FSH) is a heterodimeric glycoprotein synthesized and secreted by the anterior pituitary gland. It is composed by two subunits, a and b, being the b-subunit that confers biological specificity to the hormone. 5 The oligosaccharides attached to the FSH molecule form a variety of isoforms and the acidic isoforms were found to have a reduced bioactivity compared with the less acidic ones. 6 Although FSH receptors are expressed in granulosa cells 7 from primary follicles stage onward 8 , this hormone may act indirectly in the primordial follicles through paracrine factors secreted by larger follicles or stroma cells. Some in vitro studies have demonstrated that the addition of FSH to the culture medium promotes the maintenance of viability and preantral follicles growth in caprine 9 , as well as antrum formation in different species 10,11,12 . However, the effect of FSH in the in vitro follicular culture depends on differences among some factors, such as species, purity degree of commercial preparations of FSH and different in vitro culture systems. Furthermore, it was hypothesized that not only the quantity but also the source and the quality of FSH, in terms of isoforms and purity, plays an important role in the early