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#micropyle

3 public questions tagged with this topic.

Drosophila -l

The micropyle in Drosophila eggs primarily functions to:

Insect eggshell includes thick chorion and inner vitelline membrane impermeable to sperm. A single micropyle acts as exclusive portal, permitting only one sperm to traverse thick envelopes. Upon fertilization, vitelline membrane undergoes rapid crosslinking and hardening mediated by calcium-dependent enzymes, blocking additional sperm passage. The combination of single narrow canal and fast envelope modification provides structural polyspermy prevention. Since Drosophila eggs normally activate independently of fertilization before sperm entry, preventing multiple sperm pronuclei is critical for diploidy, making micropyle function as anatomical safeguard ensuring monospermic fertilization essential.

Ref: NCBI Bookshelf, Developmental Biology: Fertilization - polyspermy prevention in insects.

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Plant Classification

Micropyle in a seed helps in

Micropyle originates from narrow gap between integuments of ovule persisting in mature seed coat as minute pore near hilum. During germination it serves as primary portal for water imbibition initiating metabolic reactivation, enzyme synthesis like amylases, respiration increase and radicle expansion through testa. It previously allowed pollen tube entry into embryo sac during fertilization. Gas exchange occurs through general testa porosity and hilum, food storage in endosperm or cotyledons, protection by testa and tegmen. Micropylar function is critical for dormancy break demonstrated by increased germination after micropylar scarification in hard-seeded species.

Ref: NCERT Class 12 Biology Chapter 2, Ovule micropyle and germination imbibition; Raven Plant Biology

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