title: Relationships between gonadal and gonadotrophic differentiation during early gonadal sex differentiation in several strains from the Southern population of Japanese medaka (Oryzias latipes).
abstract: In this study, correlations between gonadal differentiation and gonadotrophic differentiation during early gonadal sex differentiation were examined in several strains from the Southern population of Japanese medaka, namely, Hd-rR, d-rR/Tokyo, d-rR/Shizuoka, and NIESR. Gonadal sex differentiation showed a similar pattern in all strains, that is, a sex-based difference in germ cell number was observed at hatching (XX > XY). In addition, a transition of XX germ cells into meiosis was observed at hatching in all strains. However, the ratio of meiotic transition of XX germ cells differed among strains, indicating that Hd-rR has fewer meiotic cells than other strains. Immunohistochemical analysis showed that glycoprotein α subunit (Gpa) and follicle-stimulating hormone β subunit (Fshb), but not luteinizing hormone β subunit (Lhb), localize to the pituitary at hatching in all strains examined. Although no sex differences were observed in the numbers of Gpa- and Fshb-positive cells in the pituitary at hatching in Hd-rR, d-rR/Tokyo, and NIESR strains, the d-rR/Shizuoka strain showed sex differences in the number of Fshb-positive cells at hatching (XX > XY); d-rR/Shizuoka is derived from d-rR/Tokyo. Even though d-rR/Shizuoka differs from its ancestral strain, d-rR/Tokyo, and Hd-rR in Fshb expression pattern, this suggests that d-rR/Shizuoka shows potential for use as a model to study the molecular regulatory mechanisms of fshb subunit gene expression and Fsh cell differentiation in the pituitary.
authors: Laboratory of Molecular Reproductive Biology, Graduate School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, Shizuoka, Japan.
authors: Yoshifumi
authors: Y
authors: Horie
authors: Tohru
authors: T
authors: Kobayashi
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D005260:Female; D037201:Follicle Stimulating Hormone, beta Subunit / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology; D005854:Germ Cells; D015292:Glycoprotein Hormones, alpha Subunit / Q000235:genetics / Q000378:metabolism; D006066:Gonads / Q000254:growth & development*; D037101:Luteinizing Hormone, beta Subunit / Q000235:genetics / Q000378:metabolism; D008297:Male; D009990:Oryzias / Q000235:genetics / Q000502:physiology*; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism; D012730:Sex Chromosomes / Q000235:genetics; D012733:Sex Differentiation / Q000235:genetics / Q000502:physiology*
chemical_list: D037201:Follicle Stimulating Hormone, beta Subunit; D015292:Glycoprotein Hormones, alpha Subunit; D037101:Luteinizing Hormone, beta Subunit