During late follicular development and estrus, the mammalian oviduct undergoes specific physiological and biochemical modifications which contribute to an optimization of the microenvironment for fertilization and early cleavage-stage embryonic development. These changes appear to be hormonally regulated by ovarian steroids, most importantly, estrogen. The hundreds of macromolecules found within the oviductal lumen are contributed by selective serum transudation and active biosynthesis and secretion from nonciliated epithelial cells. Recent studies have indicated temporal and regional (infundibulum, ampulla and isthmus) differences in steady-state levels of specific mRNAs and in de novo protein synthesis and secretion by the oviduct. One protein synthesized de novo, the estrogen-dependent oviductal secretory glycoprotein (OSP), has been shown to be unique to the oviduct and is conserved across a number of mammalian species. This protein associates with the zona pellucida, perivitelline space and vitelline or blastomere membrane of ovulated eggs and preimplantation embryos. OSPs have been shown to enhance sperm binding and penetration in oocytes and may regulate development in early preimplantation embryos. Other regulatory molecules, protease inhibitors, growth factors, cytokines, binding proteins, enzymes and immunoglobulins have been identified in the oviductal microenvironment. The identification and potential roles for oviduct-secreted proteins will be reviewed and discussed. Current research focuses on continued identification and characterization of specific oviductal proteins and a determination of the molecular basis of their interactions with the oocyte, sperm or embryo.

Insulin-like growth factor I (IGF-I) has been identified in human seminal plasma. This study was conducted to determine whether IGF-I is present in bovine seminal plasma, whether sperm cells express the IGF-I receptor (IGF-IR), and whether IGF-I affects sperm motility. Semen samples were collected from bulls by electroejaculation and maintained at 37 degrees C, and motility of sperm was assessed. After centrifugation to separate sperm cells from seminal plasma, the seminal plasma was submitted to a validated heterologous RIA for IGF-I. Significant concentrations of IGF-I (116.29 +/- 40.83 ng/ml expressed as mean +/- SD) were measured in bovine seminal plasma. Sperm cells were washed with buffer and subjected to either radioreceptor assay (RRA) or immunocytochemistry (IC). RRA revealed a single high affinity for the IGF-IR with a Kd of 0.83 nM as determined by the computer program LIGAND. IC, using three monoclonal antibodies, localized the IGF-IR to the acrosomal region of the sperm. Computer-assisted sperm-motion analysis was used to determine the effects of IGF-I and IGF-II on bovine sperm motility parameters. Both IGF-I and IGF-II increased sperm motility and straight-line velocity (p < 0.05) relative to the control. The presence of IGF-IR on sperm, the presence of IGF-I in semen, and the ability of IGF-I to stimulate sperm motility provide evidence that the IGF system may be involved in the fertilization process in the bovine species.

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As amphibian populations continue to decline, both government and non-government organisations are establishing captive assurance colonies to secure populations deemed at risk of extinction if left in the wild. For the most part, little is known about the nutritional ecology, reproductive biology or husbandry needs of the animals placed into captive breeding programs. Because of this lack of knowledge, conservation biologists are currently facing the difficult task of maintaining and reproducing these species. Academic and zoo scientists are beginning to examine different technologies for maintaining the genetic diversity of founder populations brought out of the wild before the animals become extinct from rapidly spreading epizootic diseases. One such technology is genetic resource banking and applied reproductive technologies for species that are difficult to reproduce reliably in captivity. Significant advances have been made in the last decade for amphibian assisted reproduction including the use of exogenous hormones for induction of spermiation and ovulation, in vitro fertilisation, short-term cold storage of gametes and long-term cryopreservation of spermatozoa. These scientific breakthroughs for a select few species will no doubt serve as models for future assisted breeding protocols and the increasing number of amphibians requiring conservation intervention. However, the development of specialised assisted breeding protocols that can be applied to many different families of amphibians will likely require species-specific modifications considering their wide range of reproductive modes. The purpose of this review is to summarise the current state of knowledge in the area of assisted reproduction technologies and gene banking for the conservation of amphibians.