Concept
Version 9
Created by Boundless
Sexual Reproduction in Angiosperms
Microsporangium
Shown is (a) a cross section of an anther at two developmental stages. The immature anther (top) contains four microsporangia, or pollen sacs. Each microsporangium contains hundreds of microspore mother cells that will each give rise to four pollen grains. The tapetum supports the development and maturation of the pollen grains. Upon maturation of the pollen (bottom), the pollen sac walls split open and the pollen grains (male gametophytes) are released. (b) In these scanning electron micrographs, pollen sacs are ready to burst, releasing their grains.
Source
Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:
"OpenStax College, Reproductive Development and Structure. October 17, 2013."
http://cnx.org/content/m44722/latest/Figure_32_01_05.jpg
OpenStax CNX
CC BY 3.0.