Gonadogenesis: Female germ cells arrested at the prophase of the first meiotic division form follicles in which they are surrounded by somatic cells in the neonatal ovary. These follicles grow and asymmetrical cell division during meiosis ensures that ovulated eggs contain maternal factors necessary for successful development. Male germ cells in mitotic arrest, post-natally enter into the reductive divisions of meiosis to form haploid round spermatids which undergo dramatic morphologic changes during spermiogenesis. Current studies investigate: 1) the role of FIGLA, a germ cell specific transcription factor required for follicle formation in female mice; 2) mechanisms that ensure asymmetric cell division during female meiosis; and 3) the role of BTBD18, a nuclear protein necessary that ensures pachytene piRNA expression necessary for spermiogenesis. Fertilization: The taxon-specificity of sperm-egg recognition in mammals that results in monospermic fertilization is mediated primarily by the zona pellucida, an extracellular matrix surrounding ovulated eggs. Although a simple structure of 3-4 glycoproteins, the molecular basis of this sperm binding to the zona pellucida has been controversial. Current studies investigate: 1) molecular requirements to support taxon-specific sperm-egg recognition on the surface of the zona pellucida; 2) mechanism that result in acrosome exocytosis necessary for gamete fusion; and 3) the processes by which post-fertilization polyspermy is prevented. Early Development: Transcription that terminates during meiotic maturation of mouse eggs resumes only after robust activation of the embryonic genome of the two-cell embryo. This interregnum between oocyte and embryonic gene transcription dictates a role for stored maternal factors. Using mouse transgenesis, the role of individual or complexes of maternal factors is studied in these processes. Current research investigates: 1) novel maternal effect genes that affect early mouse development; 2) the role of maternal organelles in the maternal to zygotic transition; and 3) the role of degradation of maternal components in activation of the embryonic genome.
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