Long-term, quantitative analysis of gametogenesis in autotriploid rainbow trout, Oncorhynchus mykiss

• Published in: Journal of reproduction & fertility Vol. 113; no. 2; pp. 197 - 210
• Main Authors: Carrasco, L A, Doroshov, S, Penman, D J, Bromage, N
• Format: Journal Article
• Language: English
• Published: England Society for Reproduction and Fertility 01-07-1998
• Subjects: Aging; Analysis of Variance; Animals; Disorders of Sex Development - genetics; Disorders of Sex Development - pathology; Female; Gametogenesis - genetics; Male; Oncorhynchus mykiss - genetics; Oncorhynchus mykiss - growth & development; Oncorhynchus mykiss - physiology; Oogenesis - genetics; Ovary - growth & development; Ovary - pathology; Polyploidy; Sex Differentiation - genetics; Spermatogenesis - genetics; Spermatozoa - pathology; Testis - growth & development; Testis - pathology
• ISSN: 1470-1626; 0022-4251; 1741-7899
• DOI: 10.1530/jrf.0.1130197

A long-term, quantitative analysis was conducted on the gametogenesis of autotriploid rainbow trout ( Oncorhynchus mykiss ) to quantify their degree of germline development and reproductive potential. Triploid and diploid (control) trout siblings
were raised separately under identical conditions and sampled randomly for histological analysis. Triploid males underwent
testicular development and proliferation of germ cells by mitosis and meiosis, progressing through initial phases of spermatogenesis
at a similar pace to diploid controls. The effects of triploidy on males were most evident during the final stages of spermatogenesis,
when all diploid males contained free spermatozoa in the lumen of most tubules (average relative frequency, ARF = 68.5%),
whereas triploid males contained predominantly spermatocytes (ARF = 36.3%) and morphologically abnormal spermatozoa (ARF =
31.8%). In contrast, the gonadal development of triploid females was affected during its early stages; the major patterns
observed were the arrest of the oogonia within oogonial clusters (ARF = 30.4–71.1%), the appearance of small numbers (ARF
= 1.5–6.0%) of previtellogenic and early vitellogenic follicles, and the proliferation of non-follicular elements (vascular
lacunae, fibrosis and tubular adenomas). In agreement with previous reports on the ovarian development of chromosomally female
(3A:ZZW) triploid chickens, male-differentiating areas (ARF = 0.2–12.2%) were observed in most triploid females examined,
which by the end of the sampling period appeared as gonadal hermaphrodites. It is hypothesized that the lack of proper somatic-to-germ
cell interactions prevents the segregation of the oocytes from the gonial clusters and may explain the early blockage observed
during the gonadal morphogenesis of autotriploid female rainbow trout.