Follicle-Stimulating Hormone Receptor: Advances and Remaining Challenges

International audienc

Cell-specific ablation in the testis:what have we learned?

Testicular development and function is the culmination of a complex process of autocrine, paracrine and endocrine interactions between multiple cell types. Dissecting this has classically involved the use of systemic treatments to perturb endocrine function, or more recently, transgenic models to knockout individual genes. However, targeting genes one at a time does not capture the more wide-ranging role of each cell type in its entirety. An often overlooked, but extremely powerful approach to elucidate cellular function is the use of cell ablation strategies, specifically removing one cellular population and examining the resultant impacts on development and function. Cell ablation studies reveal a more holistic overview of cell–cell interactions. This not only identifies important roles for the ablated cell type, which warrant further downstream study, but also, and importantly, reveals functions within the tissue that occur completely independently of the ablated cell type. To date, cell ablation studies in the testis have specifically removed germ cells, Leydig cells, macrophages and recently Sertoli cells. These studies have provided great leaps in understanding not possible via other approaches; as such, cell ablation represents an essential component in the researchers’ tool-kit, and should be viewed as a complement to the more mainstream approaches to advancing our understanding of testis biology. In this review, we summarise the cell ablation models used in the testis, and discuss what each of these have taught us about testis development and function

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