Definition of micropyle in US English:

micropyle

noun

Botany
  • 1A small opening in the surface of an ovule, through which the pollen tube penetrates, often visible as a small pore in the ripe seed.

    • ‘Only one pollen tube tip entered the nucellus through the micropyle.’
    • ‘It remains to be studied exactly how the pollen tubes reach the micropyle of the ovules.’
    • ‘However, pollen tubes from control pollen showed normal morphology when growing towards the micropyle of an ovule in a HTS plant.’
    • ‘Within the ovary, pollen tubes also grew in the ECM to penetrate the micropyle and subsequently grew intercellularly within the nucellus up to the embryo sac.’
    • ‘The ovule micropyle and embryo sac were penetrated equally by cross- and self-pollen tubes.’
    1. 1.1Zoology A small opening in the egg of a fish, insect, etc., through which spermatozoa can enter.
      • ‘Each cupule is recurved, has a lip-like projection near the point of attachment, and contains several ovules arranged in a curved row with their micropyles facing the cupule opening.’
      • ‘In a favorable situation, an opening called the micropyle appears and releases amoebocytes, which differentiate into cells of all the other types.’
      • ‘Sperm enter the anterior end of the egg through the micropyle.’
      • ‘Coupling these screens with a visual assessment of seed formation has yielded mutants defective in FG development or in the ability of pollen tubes to release their sperm after entering the micropyle.’

Origin

Early 19th century: from micro- ‘small’ + Greek pulē ‘gate’.

Pronunciation

micropyle

/ˈmaɪkrəˌpaɪl//ˈmīkrəˌpīl/