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Encephalartos villosus microsporophylls with microsporangia. A microsporangium (pl. microsporangia) is a sporangium that produces microspores that give rise to male gametophytes when they germinate. Microsporangia occur in all vascular plants that have heterosporic life cycles, such as seed plants, spike mosses and the aquatic fern genus Azolla.
In botany, the theca is related to plant's flower anatomy. The theca of an angiosperm consists of a pair of microsporangia that are adjacent to each other and share a common area of dehiscence called the stomium. [1] Any part of a microsporophyll that bears microsporangia is called an anther. Most anthers are formed on the apex of a filament.
Conifers typically bear their microsporangia on microsporophylls aggregated into papery pollen strobili, and the ovules, are located on modified stem axes forming compound ovuliferous cone scales. Flowering plants contain microsporangia in the anthers of stamens (typically four microsporangia per anther) and megasporangia inside ovules inside ...
The lumbar cistern is part of the subarachnoid space.It is the space within the thecal sac which extends from below the end of the spinal cord (the conus medularis), typically at the level of the first to second lumbar vertebrae down to tapering of the dura at the level of the second sacral vertebra.
The arteries of the base of the brain. Superior cerebellar artery labeled near center. The temporal pole of the cerebrum and a portion of the cerebellar hemisphere have been removed on the right side (left half of diagram). Inferior aspect (viewed from below). The superior cerebellar artery supplies deep parts and superior parts of the cerebellum.
The cerebral arteries describe three main pairs of arteries and their branches, which perfuse the cerebrum of the brain. The three main arteries are the: Anterior cerebral artery (ACA), which supplies blood to the medial portion of the brain, including the superior parts of the frontal and anterior parietal lobes [1]
The arteries of the base of the brain. Posterior inferior cerebellar artery labeled at bottom. The temporal pole of the cerebrum and a portion of the cerebellar hemisphere have been removed on the right side. Inferior aspect (viewed from below).
The leptomeningeal collateral circulation (also known as leptomeningeal anastomoses or pial collaterals) is a network of small blood vessels in the brain that connects branches of the middle, anterior and posterior cerebral arteries (MCA, ACA, and PCA), [1] with variation in its precise anatomy between individuals. [2]