Pollen tube the pollen tube responds to extracellular guidance signals to achieve fertilization. Pollen tubes are produced by the male gametophytes of seed plants. They act as conduits to transport the male gamete cells from the pollen grain—either from the stigma (in flowering plants) to the ovules at the base of the pistil or directly through ovule tissue in some gymnosperms. Pollen tubes were first discovered by Giovanni Battista Amici. Pollen tube formation is important for sexual reproduction to occur in seed plants. Plants have separate structures such as microsporocytes and megasporocytes and the pollen grains are transported to the female gametophyte
Bacillus spore morphogenesis and germination holin family about 90 amino acyl residues in length and exhibit 3 transmembrane segments (TMSs). A representative list of homologous proteins, found only in "Bacillus" species, is available in the Transporter Classification Database. Bacillus spore morphogenesis and germination holin family The "Bacillus" Spore Morphogenesis and Germination Holin (BSH) Family (TC# 1.E.23) is a family of proteins named after a holin in "Bacillus subtilis" described to be involved in spore morphogenesis and germination by Real et al (2005). The gene encoding this holin is "ywcE." Mutants lacking this gene or its product have spores that exhibit outer coat defects. These spores lack the