Blastic Conidia

  • Develop by a BUDDING or SWELLING PROCESS.
  • May develop as SINGLE SPORES or in succession to form a CHAIN OF SPORES.
Blastospores:
Diagram illustrating formation of blastospores.
  • Formed by budding of a hypha or yeast cell.
  • Both wall layers are involved.
  • The spore may remain attached and bud further blastospores - giving rise to a branched chain of spores.
Porospores:
Diagram illustrating formation of porospores.
  • The developing spore emerges through a distinct 'pore' in the hyphal wall.
  • Only the inner layer of the hyphal wall is involved in spore development.
  • The new spore then develops its own new inner wall layer.
  • The outer spore wall is often thickened and pigmented.
  • A scar is usually obvious at the point of detachment from the hypha (conidiophore).
Aleuriospores:
Diagram illustrating formation of aleuriospores.
  • Develop as single, terminal spores.
  • Conidiophore apex inflates and becomes separated by a septum at an early stage in spore development.
  • Both wall layers are involved in spore formation .
  • The spore possesses a wide, truncate scar.
  • Normally no further development of spores occurs at the point of detachment.
  • So the next spore usually has to develop by production of a branch below the scar on the conidiophore.
Annellospores:
Diagram illustrating annellospore formation.
  • In some species that form conidia in a manner similar to that described for aleuriospores (see above) a new growing point DOES develop at the scar.
  • A chain of spores may develop.
  • The conidiophore gets a little longer with each spore produced.
  • Annellations (ring-like scars) are observed around this elongating portion.
  • Each annellation represents the production of one annellospore.
Phialospores:
Diagram illustrating phialospore formation.
  • Form in succession .
  • Each spore is pushed up from the tip of the conidiophore, which is now called a PHIALIDE.
  • The spore wall is new and distinct from both wall layers of the phialide.
  • The first spore has a cap, which represents the tip of the phialide wall through which the spore emerged - all other spores in the chain are smoothly rounded.
Photomicrograph illustrating conidia formation in Penicillium. - CLICK TO VIEW LIGHT MICROGRAPH OF CONIDIA FORMATION IN PENICILLIUM - 77 KB.
Scanning electron micrograph of sporulation in Penicillium. - CLICK TO VIEW SCANNING ELECTRON MICROGRAPH OF CONIDIA FORMATION IN PENICILLIUM - 56 KB

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