title: Species differences in the ovarian distribution of 3beta-hydroxysteroid dehydrogenase/delta5-->4 isomerase (3beta-HSD) in two marsupials: the brushtail possum Trichosurus vulpecula and the grey, short-tailed opossum Monodelphis domestica.
abstract: The ovarian distribution of the steroidogenic enzyme 3beta-hydroxysteroid dehydrogenase/delta(5-->4) isomerase (3beta-HSD) was investigated by immunocytochemistry in two marsupial species throughout the reproductive cycle, using a rabbit polyclonal antibody raised against human placental 3beta-HSD. In the polyoestrous and polyovular South American opossum Monodelphis domestica, immunostaining was positive for 3beta-HSD in the adrenal cortex, the ovarian interstitial tissue, the corpus luteum and the granulosa cells of antral and atretic follicles. The theca interna was weakly positive for 3beta-HSD, but only in late preantral to early antral stages of follicular development. The adrenal medulla and smaller preantral follicles were completely negative for 3beta-HSD. In contrast, in the polyoestrous and monovular Australian brushtail possum Trichosurus vulpecula, immunostaining showed a strong positive reaction for 3beta-HSD in the theca, whereas the granulosa layer remained predominantly negative for 3beta-HSD except in the largest follicles. The atretic follicles were completely negative for 3beta-HSD. The ovaries of pregnant animals contained grossly enlarged, persistent, antral follicles, which reacted positively for 3beta-HSD. The function of these follicles in T. vulpecula and the 3beta-HSD-positive atretic follicles in M. domestica has not been determined. The differences between the two marsupials represent species variations. The situation in M. domestica does not represent a marsupial-eutherian dichotomy as previously conjectured.
authors.affiliation: Division of Environmental and Evolutionary Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK. gbza82@udcf.gla.ac.uk
authors.forename: S L
authors.initials: SL
authors.lastname: Ullmann
authors.forename: A J
authors.initials: AJ
authors.lastname: Russell
authors.forename: J I
authors.initials: JI
authors.lastname: Mason
authors.forename: L
authors.initials: L
authors.lastname: Selwood
mesh_terms: D015096:3-Hydroxysteroid Dehydrogenases / Q000032:analysis*; D000302:Adrenal Cortex / Q000201:enzymology; D000818:Animals; D003338:Corpus Luteum / Q000201:enzymology; D030762:Estrous Cycle / Q000378:metabolism*; D005260:Female; D006107:Granulosa Cells / Q000201:enzymology; D007150:Immunohistochemistry / Q000379:methods; D008394:Marsupialia / Q000378:metabolism*; D009893:Opossums / Q000378:metabolism; D006080:Ovarian Follicle / Q000201:enzymology; D010053:Ovary / Q000201:enzymology*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D013045:Species Specificity; D013799:Theca Cells / Q000201:enzymology
chemical_list: D015096:3-Hydroxysteroid Dehydrogenases