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The Energetics of Fish Sperm Motility
Published in Claude Gagnon, Controls of Sperm Motility, 2020
There are two main patterns of fertilization that can be identified in fish: copulation and internal fertilization of oocytes in their follicules in the case of ovoviviparous species, and external fertilization with release of gametes in the water in oviparous species. The energy requirement by the spermatozoa is strongly related to the modes of fertilization which will be first described as an introduction to this chapter.
Disruption of Nongenomic Steroid Actions on Gametes and Serotonergic Pathways Controlling Reproductive Neuroendocrine Function by Environmental Chemicals
Published in Rajesh K. Naz, Endocrine Disruptors, 2004
Several lines of evidence suggest the MIS receptor on croaker sperm is an important intermediary on sperm activation. Incubation of sperm with 20β-S, but not with other steroids, increases the percentage that are motile as well as sperm velocity and their turning rate. This stimulatory effect of 20β-S is concentration dependent and is enhanced if 20β-S receptor concentrations on croaker sperm are upregulated by prior in vivo treatment with LHRH [125]. Incubation with 20β-S also causes rapid increases in intrasperm free calcium concentrations [125]. These studies suggest, therefore, that 20β-S activates croaker sperm by elevating intracellular free calcium levels and that the process is dependent upon sufficient numbers of MIS sperm membrane receptors and functional calcium channels. Thus, it is proposed that the basic mechanism of sperm activation by progestins in the male reproductive tract of a teleost species with external fertilization is similar to that induced by progesterone in the female tract of a vertebrate group with internal fertilization, the mammals.
ENTRIES A–Z
Published in Philip Winn, Dictionary of Biological Psychology, 2003
In mammals, ovulatory cycles follow three distinct patterns. In Type 1 cycles, both ovulation and PSEUDOPREGNANCY are spontaneous, with the length of the cycle being either medium (as in female great apes and humans) or long (as in canines). For these females, sexual behaviour can be either constrained to a periovulatory period (as in some rodents and guinea pigs) or not constrained (as in humans). In Type 2 cycles, ovulation occurs only following requisite copulatory stimulation (typically vaginocervical stimulation from the penis), however pseudopregnancy is spontaneous. As with Type 1 females, some cycles are of moderate duration (for example in rabbits) whereas others are of long duration (for example in ferrets). In Type 3 cycles, ovulation is spontaneous but pseudopregnancy requires prolactin release that is induced by copulatory stimulation (in rats and hamsters for instance). The process of pregnancy and subsequent parental behaviour also differs greatly in different species. Mammals maintain the fertilized egg and FOETUS within a UTERUS for the duration of pregnancy. Other species, like birds, enclose the egg within a hard shell and deposit it after copulation into a nest, where it will be incubated until the offspring hatch. Still others, like some species of fish, deposit eggs with a SEMIPERMEABLE MEMBRANE into the water or patches of mud for subsequent external fertilization.
Exploring Cisgender Women’s Experiences of Reproductive Loss After In Vitro Fertilization
Published in Women's Reproductive Health, 2023
Meghan Forgie, Amanda Vandyk, Wendy Peterson, Danielle Dubois
Infertility is the inability to conceive despite frequent, unprotected sex over the span of one year (Zegers-Hochschild et al., 2009). Globally, approximately 48 million couples live with infertility (Mascarenhas et al., 2012; World Health Organization, 2021). In some countries, such as Canada, infertility has doubled in the last four decades (Public Health Agency of Canada, 2019). In vitro fertilization—the process of external fertilization of the egg with sperm and the subsequent embryo transfer into the uterus (Zegers-Hochschild et al., 2009)—is a treatment option for infertility. Unfortunately, nearly 70% of people who undergo in vitro fertilization experience an unsuccessful attempt or treatment failure, and approximately 20% of pregnancies achieved through in vitro fertilization, using one’s own oocytes, result in miscarriage (Canadian Fertility & Andrology Society, 2019). Reproductive losses, such as treatment failure and miscarriage following the use of assisted reproductive technologies, can lead to stress disorders and increased levels of anxiety (Farren et al., 2016), problems within the partner relationship (Gold et al., 2010; Luk & Loke, 2019; Shreffler et al., 2012), as well as sadness and mourning (Brier, 2008; Fenstermacher & Hupcey 2013; Gameiro & Finnigan, 2017). Research has also shown that the use of in vitro fertilization itself has physical, psychological, emotional, and financial consequences (Boivin et al., 2012).
Social Monogamy in Nonhuman Primates: Phylogeny, Phenotype, and Physiology
Published in The Journal of Sex Research, 2018
Jeffrey A. French, Jon Cavanaugh, Aaryn C. Mustoe, Sarah B. Carp, Stephanie L. Womack
The first definitional issue in the study of monogamy involves identifying the biological level being addressed (Gowaty, 1996). At its most fundamental definition, monogamy can be defined at the level of genes: genetic monogamy. According to this definition, monogamy is present when the genes contained in gametes from one individual combine only with the genes contained in gametes from a second individual. This fundamental definition has little to do with either the common notion of monogamy or the use of the term in natural and social sciences. Further, it can also lead to some interesting conundrums. For instance, consider an invertebrate species with external fertilization in which males and females are completely solitary, never engage in a single social interaction, and distribute sperm and egg into the environment. If gametes from one individual only combine with gametes of one other individual, this species would qualify as monogamous. Alternatively, an otherwise loving and committed human couple who conceive via in vitro fertilization from an unrelated sperm or egg donor would not qualify as genetically monogamous. While popular culture suggests that extrapair (i.e., nonmonogamous) paternity is frequent, recent analyses have suggested that these rates are low both historically and in contemporary times, at least in Western cultures (Larmuseau, Matthijs, & Wenseleers, 2016). Nonetheless, departures from genetic monogamy do occur in human populations.
In vivo toxicity assays in zebrafish embryos: a pre-requisite for xenograft preclinical studies
Published in Toxicology Mechanisms and Methods, 2019
Carlha Gutiérrez-Lovera, Jeannette Martínez-Val, Pablo Cabezas-Sainz, Rafael López, Juan A. Rubiolo, Laura Sánchez
The zebrafish model has emerged as a powerful in vivo tool in the oncology field due to its advantages in comparison with mice models. Among these, the most relevant are that zebrafish: (i) is a straightforward and low cost small animal model (Rojas-Muñoz et al. 2007), (ii) has high fecundity and external fertilization (Kimmel et al. 1995), (iii) is optically transparent, (iv) has a short reproductive cycle, (v) is permeable to small molecules (Henn and Braunbeck 2011), and (vi) has a genome with high homology (∼85%) with that of humans (Renier et al. 2007; McCollum et al. 2011) and with several organs and tissues resembling those of humans. All these features make possible large-scale assays and even high-throughput screening (Mimeault and Batra 2013).