Search results for "Ovotestis"

Cytogenetics in the sacoglossan Oxynoe olivacea (Mollusca: Opisthobranchia): karyotype, chromosome banding and fluorescent in situ hybridization

2000

Developing embryos and sexually mature follicles of the male portion of ovotestis proved to be a suitable material as a source of cleaving cells for advanced cytological investigations on the sacoglossan species Oxynoe olivacea Rafinesque, 1819 (Mollusca: Opisthobranchia). O. olivacea has a diploid chromosomal number of 30 made up of 15 pairs of which six are metacentric/submetacentric (M/SM), four subtelocentric (ST) and five on the borderline between SM and ST. Correspondingly, 15 bivalents occur in spermatocytes at Metaphase I. Constitutive heterochromatin is scarce and restricted to small C-bands seen in five pachytene bivalents. The use of combined silver staining and fluorescent in si…

2002

Analysis of gonad organization and development revealed that Serranus atricauda is a functional simultaneous hermaphrodite. The ovary is classified as asynchronous. Oocyte growth is divided into five stages: stage I (primary growth stage), stage II (yolk vesicle formation), stage III (vitellogenesis), stage IV (oocyte maturation) and stage V (mature egg). The testis is of the unrestricted or lobular spermatogonial type. Spermatogenic cells include spermatogonia, primary and secondary spermatocytes, spermatids (which form cysts in the seminiferous tubules) and spermatozoa (free in the lumen). The histological structure of the gonad and sperm morphology would seem to indicate that this specie…

Protandric hermaphrodite peculiarities in Amphiprion frenatus Brevoort (Teleostei, Pomacentridae)

1990

Electron microscopy of the male phase of the ovotestis of Amphiprion frenatus, a protandric hermaphrodite, showed no connective tissue between male and female areas and, as the basal lamina was lacking both along the seminiferous tubules and round the previtellogenic oocytes, the male and female germ cells were only separated by their respective surrounding somatic cells (Sertoli and follicle cells). Besides previtellogenic oocytes, oocytes in meiotic prophase and very small (young) previtellogenic oocytes, were detected in the ovarian part, as spermatogenesis proceeded, revealing oogenetic activity. Degeneration of some previtellogenic oocytes and their follicle cells was discernible.