Electron microscope studies of Saintpaulia ionantha Wendl. pollen walls

Physiology and Cytology of Anther Developmeent

“…Similar observations have been made in Saintpaulia ionantha Wendl. (Ehrlich, 1958). Larson & Lewis (1961 also observed the presence of cytoplasmic channels in the developing and mature exine as well as the intine of Parkinsonia aculeata indicating that 'microspore and pollen protoplasts maintain cytoplasmic connexions with the exine '.…”

“…This is why even in sterile and aborted microspores or pollen, a normal exine pattern and development is seen. Intine, however, is not formed in aborted pollen (Ehrlich, 1958). On the basis of similarity in the ornamentation of the spheroids with the exine in the Pinaceae, Degeneriaceae and the Gramineae, Rowley et al (1959) feel that 'either the influence of the pollen protoplast over exine form extends outward for a considerable distance, or exine development is at least partially controlled from the outside'.…”

Ontogeny of pollen wall ofleontodon autumnalis(hypochoeridinae, compositae)

“…On the other hand, the ontogeny of the tectum in Leoritodori differs from that of other genera in which the tectum is formed over the distal ends of radially oriented probacules inserted into the primexine matrix as in Sriiritpairlia (Ehrlich 1958), Silerie (HeslopHarrison 1963), I'nrliirisoriio (Larson & Lewis 1962), Iporiiueri (Godwin et al 1967) and llelicinthirs (Horner & Pearson 1978). In Leontodori the pretectal period is distinguished from that ofhtenrisin by the deposition of strongly stainable patches appearing to be detached from the plasma membrane.…”

A Possible Role for the Endoplasmic Reticulum in Exine Formation

“…Since it has bcen reported that exine material appears whilst the microspores are still enclosed within the tetrad callose wall (Ehrlich, 1958;Dickinson & HeslopHarrison, 1968;HeslopHarrison, 1968;Mepham & Lane, 1968;Heslop-Harrison, 1973;Waterkeyn, 1973), and since the intine develops after release of the microspores from the tetrad wall and the formation of cxine pattern, it seems obvious that the electron-dense material whichappears during the later stages of microsporogenesis in Bcrberis vrilgaris represents exinc. The deposits of electrondense material, particularly abundant on the surface of the plasmalemma of the tetrad cells, do not represent the first exine layer-primexine, sincc it is known that the primexine is composed of fibrillar material containing isolated, dressed probacula, which appear to be amorphous, granular or lamellate in structure depending upon the preparative technique used (HeslopHarrison, 1973;Waterkeyn, 1973).…”