Pollen are the tectum and the foot layer, which is just above the intine. The tectum and foot layer are separated by a region called the columella, which is composed of strengthening rods. The outer wall is constructed with a resistant biopolymer called sporopollenin. Pollen apertures are regions of the pollen wall that may involve exine thinning or a significant reduction in exine thickness. They allow shrinking and swelling of the grain caused by changes in moisture content. Elongated apertures or furrows in the pollen grain are called colpi (singular: colpus) or sulci (singular: sulcus). Apertures that are more circular are
Spore (agricultural publication) publisher, CTA. Recent Special Issues have covered Climate Change (2015), Family Farming (2014), Structured Grain Trading (2013); Agricultural Value Chains (2012); Modernizing Farms (2011) and Population and Agriculture (2010). Issues from September 1997 (No. 72) to the present are available at the magazine's website . Issues 1-69 are available from . Spore (agricultural publication) Spore is a magazine published by the Technical Centre for Agricultural and Rural Cooperation ACP-EU (CTA) in English and French. It covers a wide range of agricultural topics and is extensively distributed and widely reproduced throughout African, Caribbean and Pacific (ACP) countries and elsewhere. Originally known