Effect of semen storage on the number of spermatozoa in the perivitelline layer of laid turkey eggs

A progressive decline in fertility over the course of egg production may be observed when turkey hens are inseminated weekly with semen stored for 24 h. In vitro storage of spermatozoa before insemination results in lower fertilization, possibly because fewer spermatozoa survive selection and storage in the hen\u27s sperm storage tubules in vivo; alternatively, stored spermatozoa may be as capable of reaching the egg as are fresh spermatozoa, but unable to penetrate and fertilize the egg normally. The objective of this study was to determine whether this decline in fertility is a result of fewer spermatozoa reaching the egg after insemination with spermatozoa stored in vitro. Hens were inseminated weekly over the first 12 weeks of egg production with either fresh semen (n = 30 hens) or semen stored for 24 h (n = 30 hens). A total of 301 eggs was evaluated by determining the density distribution of spermatozoa embedded in the outer perivitelline layer. For the 12 weeks of egg production, the fertility of hens inseminated with fresh semen remained greater than 94%. Conversely, the percentage fertility of eggs from hens inseminated with stored semen in weeks 1-3 was greater than 94% but thereafter fertility averaged 86%. There was no difference in hatchability of fertile eggs between the two treatments over all weeks combined, and weekly throughout the study (P \u3e 0.05). The mean number of spermatozoa in the perivitelline layer was higher (P \u3c 0.001) when hens were inseminated with fresh (12.1 ± 1.3 spermatozoa per 5.5 mm2 membrane) versus stored semen (2.5 ± 0.3 spermatozoa per 5.5 mm2 membrane) over all weeks combined, and weekly throughout the study (P \u3c 0.05). As a result of storage for 24 h, fewer spermatozoa are stored in the sperm storage tubules and, consequently, fewer spermatozoa are present at the site of fertilization, thus contributing to the depressed fertility

Thyroid disruption in the lizard Podarcis bocagei exposed to a mixture of herbicides: a field study

Pesticide exposure has been related with thyroid disrupting effects in different vertebrate species. However, very little is known about the effects of these compounds in reptiles. In the Mediterranean area, lacertid lizards are the most abundant vertebrate group in agroecosystems, and have been identified as potential model species for reptile ecotoxicology. The aim of this study was to understand if the herbicides applied in corn fields have thyroid disruptive effects in the lizard Podarcis bocagei. Adult male lizards were captured in north-western Portugal in corn fields treated with herbicides (exposed sites), and in organic agricultural fields (reference sites). Thyroid and male gonad morphology and functionality, and testosterone levels were investigated through histological, immunohistochemical and biochemical techniques. Lizards from exposed locations displayed thyroid follicular lumens with more reabsorption vacuoles and significantly larger follicular area than those from reference fields. Furthermore, testes of lizards from exposed locations had significantly larger seminiferous tubule diameters, significantly higher number of spermatogenic layers and displayed an upregulation of thyroid hormone receptors when compared with lizards from reference areas. These findings strongly suggest that the complex mixture of herbicides that lizards are exposed to in agricultural areas have thyroid disrupting effects which ultimately affect the male reproductive system. Alachlor, which has demonstrated thyroid effects in mammals, may be largely responsible for the observed effects.We appreciate the assistance of Ricardo Valente and CIBIO members. All lizards were collected under a permit issued by the Instituto da Conservac¸a˜o daNatureza e Biodiversidade.This research and the technical position of R.C. Bicho was supported by FEDER through COMPETE-Programa Operacional Factores de Competitividade and National funding through FCT-Fundac¸a˜o para a Cieˆncia e Tecnologia, within the research project LAB-PET—Lacertid Lizards as Bioindicators of Pesticide Exposure and Toxicity in intensive market garden agriculture (FCT PTDC/AMB/64497/2006). M. J. Amaral benefited from a doctoral grant from FCT (SFRH/BD/31470/2006)