Ultrastructural changes in maturing sporangia of Albugo Candida

Maturation of sporangia in Albugo sp. involved considerable internal differentiation. There was a burst of activity in sporangia soon after their formation when the numbers of mitochondria, and the amounts of endoplasmic reticulum increased. Perinuclear vesicles and smooth surfaced cisternae differentiated into well-developed golgi apparatus which remained secretory until completion of maturation. The cisternae of rough endoplasmic reticulum arranged themselves in parallel stacked arrays. Maturing sporangia had autophagic vacuoles containing various cell organelles. Nuclear degeneration and mitosis proceeded simultaneously. All activities declined towards the end of sporangial maturation: Golgi dictyosomes became quiescent and numbers of mitochondria and amounts of endoplasmic reticulum decreased. There was a three-fold increase in the thickness of the sporangial wall during maturation.