(n.) One of the specially large spores of certain flowerless plants, as Selaginella, etc.
Example Sentences:
(1) Careful examination of these failed to reveal typical arthrospores or Fusarium macrospores despite substantial recoveries of corresponding growth in culture.
Megaspore
Definition:
Example Sentences:
(1) The first, or parasitic classifications of Sabouraud, rests on the morphology of the dermatophytes on the hair in vivo (Achorion, Trichophyton endothrix or ectothrix microides and megaspores, Microsporum) or on the absence of growth on the hair in vivo (Epidermophyton).
(2) The more mature megaspore of Isoetes contains proplastids up to 4 mum in greatest dimension.
(3) The disposition of these organelles in the cell is such that each of the four megaspores delimited during cytokinesis contains a single proplastid.
(4) In Isoetes all 4 megaspores of every tetrad survive and develop, while in Marsilea the mature megasporangium contains a single functional megaspore.
(5) beta-Lectin activity is absent from the megaspore wall.
(6) The resemblance of the plastids in the more mature megaspore to the bodies produced by evagination earlier in development suggests a common identity.
(7) It is possible, however, in the megaspore at least, that the distribution of the activity may to some extent be influenced by a system of exine channels which communicates between the two domains of the wall during sporogenesis.
(8) It is suggested that an explanation to account for the 2 different mechanisms might be sought in regard to the degree of developmental success enjoyed by the individual megaspores in the 2 plants.
(9) The earlier changes observed are in the megaspore which contained many reserve substances (starch; nucleic acids; ascorbic acid; proteins) and enzymes (peroxidase, succinate dehydrogenase, acid phosphatase, alkaline phosphatase and ATP-ase).
(10) The spermatozoid approaches the egg through layers of mucilage that surround the megaspores.