Ovarian Structure in Mice Lines Selected for Weight

Abstract

Selection for body weight at 49 day of age (s and h, downward selected lines; s' and h', upward selected lines) affected reproductive traits in CF1 mice lines. The objective of this study was to compare ovarian structures in females of these lines, as well as in unselected controls (Line t). The number of ovarian follicles (N), follicle diameter (FD), number of corpora lutea (CL), litter size (LS), and body weight (W), were recorded. There were significant differences among lines for N, FD, CL, LS and W; means values for the lines with the greatest difference for post-pubertal females were: N(s) = 19.3 and N(s') = 32.7; FD(h') = 161.7 and FD(s') = 178.2; CL(h) = 10.3 and CL(s') = 21.9; LS(s) = 6.0 and LS(h') = 11.1; W(h) = 18.9 and W(s') = 32.4. There were also differences between positive lines; Line s' had a higher proportion of large follicles in pre-pubertal females, a greater capacity to convert these follicles into CL, but a lower capacity to maintain embryos until term than Line h'. For negative lines, Line h apparently had a reduced incidence of embryonic loss when compared with Line s. In conclusion, selection for body weight modified ovarian structure, as well as reproductive efficiency.

The evolution of phenotypic integration: How directional selection reshapes covariation in mice

“…The difference in the number of breeders between upwards and downwards lines was due to the lower fertility of the lightest mice (Bernardi et al. 2009). Full‐sib mating was also avoided in all the selected lines, except for the first generations of h and h' lines.…”

“…Average effective population size of selected lines was maintained selecting six breeders of each sex for the downwards lines and four breeders of each sex for upwards lines. The difference in the number of breeders between upwards and downwards lines was due to the lower fertility of the lightest mice (Bernardi et al 2009). Full-sib mating was also avoided in all the selected lines, except for the first generations of h and h' lines.…”

Evaluation of Three Mathematical Functions to Describe the Relationship Between Body Weight, Body Condition and Testicular Dimensions in Yankasa Sheep

“…Sperm competition is a common phenomenon across the animal kingdom and is recognized as a major factor in the sexual selection of males. Because the testes produce sperm and reflect investment in ejaculates, one of the predicted consequences of sperm competition is that the testes should be relatively large when the likelihood of sperm competition is high (Schulte-Hostedde et al, 2005;Bernardi et al, 2010). In the male for instance, there is the need to establish measurable criteria for judging breeding soundness and guiding selection of males for breeding.…”

Efectos de la Selección y de la Superovulación en las Pérdidas Gestacionales de Ratonas CF1

“…Sin embargo, al analizar la estructura ovárica se comprobó que el desarrollo de los folículos ováricos y la capacidad ovulatoria no explicaban el mayor tamaño de camada de las hembras de esta línea. Las hembras de la línea más pesada fueron las que mostraron diámetros mayores de los folículos ováricos y números mayores de folículos y de cuerpos lúteos, que no se expresaron en un mayor tamaño de camada al nacimiento (Bernardi et al, 2009). Este incremento del número de oocitos ovulados atribuible a la selección para alto peso, sin un aumento proporcional del tamaño de camada a la parición, podría deberse a diferencias en las pérdidas embrionarias ocurridas en distintas etapas de la gestación.…”