Long-lived iteroparous species often show aging-related changes in reproduction that may be explained by 2 non-mutually exclusive hypotheses. The terminal investment hypothesis predicts increased female reproductive effort toward the end of the life span, as individuals have little to gain by reserving effort for the future. The senescence hypothesis predicts decreased female reproductive outpu...

In birds, larger females generally have greater breeding propensity, reproductive investment, and success than do smaller females. However, optimal female body size also depends on how natural selection acts during other parts of the life cycle. Larger female Lesser Scaup (Aythya affinis) produce larger eggs than do smaller females, and ducklings from larger eggs survive better than those hatch...

The considerable variation in adult size of the boll weevil, Anthonomus grandis grandis Boheman, has been well documented, but the influences of adult size on reproductive rate are not known. We examined the relationship between the size of boll weevils and their feeding and oviposition. Weevils weighed to the nearest milligram were grouped into five categories based on pupal weight: < or =5, 6...

Potential variation in reproductive performance as young broodfish among four selectively bred strains of channel catfish was evaluated by comparing profiles of plasma estradiol, testosterone, and vitellogenin, and activities of cathepsin D, L, and B in follicle-enclosed oocytes during vitellogenesis in 2to 3-yr-old females. No differences among the four strains were detected for any of the par...

A sample of 213 healthy Czech women was classified into four groups according to their reproductive phase: fully reproductive, premenopausal, menopausal and postmenopausal women. Changes in body weight, body composition and fat distribution were studied in those four groups using the classical anthropometric method. Body weight rises till the menopause with no further increase. A decrease in re...

The reproductive toxicity of propoxur (2-isopropoxy-phenyl-N-methylcarbamate), a carbamate pesticide, was investigated in adult male Wistar rats exposed to 0, 1.73, 2.6, and 5.2 mg/kg body weight/day for 90 successive days. Results obtained from this study showed a significant (p < 0.05) concentration-dependent increase in food consumption, relative weights of testis, epididymis and kidneys wit...

The loss of reproductive capacity during aging involves changes in the neural regulation of the hypothalamic gonadotropin-releasing hormone (GnRH) neurons controlling reproduction. This neuronal circuitry includes glutamatergic receptors on GnRH neurons. Previously, the Gore lab reported an increase in the expression of the NR2b subunit protein of the NMDA receptor on GnRH neurons in middle-age...

the aim of this study was to evaluate the effect of ecg, pgf2α, and combination of ecg and pgf2α early postpartum on reproductive performance in high producing dairy cows. three hundred sixty eight postpartal holstein dairy cows were divided in 4 groups. cows in groups 1 and 2 received 500 iu ecg on day 8 ± 2 and cows in groups 3 and 4 received saline. cows in groups 1 and 3 received injections...

The aim of this study was to evaluate the protective effects of Ginkgo biloba (GB) against testicular damage and oxidative stress as well as caudal sperm indices in a cisplatin- (CIS-) induced rodent model. Adult male Wistar rats were given vehicle, single i.p. dose of CIS alone (10 mg/kg), GB alone (200 mg g/kg every day for five days), or single dose of CIS followed by GB (50, 100, or 200 mg/...

BACKGROUND Polybrominated diphenyl ethers (PBDEs) are capable of disrupting thyroid hormone homeostasis. PBDE-47 (2,2',4,4'-tetrabromodiphenyl ether) is one of the most abundant congeners found in human breast adipose tissue and maternal milk samples. OBJECTIVES We evaluated the effects of developmental exposure to low doses of PBDE-47 on the female reproductive system. METHODS Pregnant Wis...