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Megasporogenesis, formation of the megaspores in the megasporangium (nucellus) by meiosis; Megagametogenesis; development of the megaspore(s) into the megagametophyte(s) which contains the gametes. [2] In gymnosperms and most flowering plants, only one of the four megaspores is functional at maturity, and the other three soon degenerate.
Areas 1 and 2 receive most of their input from area 3. There are also pathways for proprioception (via the cerebellum), and motor control (via Brodmann area 4). See also: S2 Secondary somatosensory cortex. The human eye is the first element of a sensory system: in this case, vision, for the visual system.
In some species, including fish and birds, the optic tectum, also known as the optic lobe, is one of the largest components of the brain. Note on terminology: This article follows terminology established in the literature, using the term "superior colliculus" when discussing mammals and "optic tectum" when discussing either specific non ...
The retrosplenial cortex (RSC) is a cortical area in the brain comprising Brodmann areas 29 and 30. [1] It is secondary association cortex, making connections with numerous other brain regions. The region's name refers to its anatomical location immediately behind the splenium of the corpus callosum in primates, although in rodents it is ...
The area of the visual cortex that receives the sensory input from the lateral geniculate nucleus is the primary visual cortex, also known as visual area 1 , Brodmann area 17, or the striate cortex. The extrastriate areas consist of visual areas 2, 3, 4, and 5 (also known as V2, V3, V4, and V5, or Brodmann area 18 and all Brodmann area 19). [1]
In terms of Brodmann areas, the extrastriate cortex comprises Brodmann area 18 and Brodmann area 19, while the striate cortex comprises Brodmann area 17. [3]In primates, the extrastriate cortex includes visual area V3, visual area V4, and visual area MT (sometimes called V5), [3] while V1 corresponds to the striate cortex, and V2 to the prestriate cortex.
Megaspores, also called macrospores, are a type of spore that is present in heterosporous plants. These plants have two spore types, megaspores and microspores. Generally speaking, the megaspore, or large spore, germinates into a female gametophyte, which produces egg cells.
A sporangium (from Late Latin, from Ancient Greek σπορά (sporá) 'seed' and ἀγγεῖον (angeîon) 'vessel'); pl.: sporangia) [1] is an enclosure in which spores are formed. [2]