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#egg development

4 public questions tagged with this topic.

Sea urchin -l

Egg cytoplasmic stores do NOT contain:

Unfertilized sea urchin egg cytoplasm stockpiles abundant maternal resources sustaining rapid early cleavages without transcription. Stores include ribosomes, tRNAs, maternal mRNAs encoding histones, actin, cyclins, morphogenetic determinants like Disheveled and β-catenin regulators, and nutritive yolk proteins supporting metabolism. Protective chaperones and translational repressors maintain readiness for activation. Sperm-activating chemotactic peptides such as resact and speract are synthesized by follicle cells and secreted into gelatinous jelly layer surrounding egg, functioning externall

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 7: Egg cytoplasmic reserves and egg jelly peptides.

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Sea urchin -l

Cortical granules are homologous to:

Cortical granules are dense membrane-bound vesicles arranged in monolayer underlying egg plasma membrane, stockpiled with proteases, peroxidase, glycosaminoglycans and structural proteins destined for rapid Ca2+-triggered exocytosis at fertilization. Detailed ultrastructural and biochemical comparison demonstrates striking homology with acrosomal vesicles of spermatozoa – both derive from Golgi apparatus in their respective gametes, contain hydrolytic enzymes, and undergo regulated SNARE-mediated exocytosis releasing contents to modify extracellular coats. Functionally, cortical reaction trans

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 7: Cortical granules and acrosome vesicle homology.

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Drosophila -l

Which region of Drosophila egg defines the site of sperm entry?

Micropyle is anterior conical channel through chorion and vitelline membrane produced by specialized border follicle cells, providing sole continuity between exterior and ooplasm. Sperm swims through this canal to reach egg cytoplasm since eggshell otherwise impermeable. Position defines anterior site of sperm entry where male pronucleus meets female pronucleus residing anteriorly after meiosis. Unlike amphibian vegetal pole or blastopore gastrulation structure, Drosophila entry point is anatomically predetermined by micropyle. After fertilization micropyle becomes sealed, and vitelline membra

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 3: Micropyle as sperm entry site.

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