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An anther and its filament together form a typical (or filantherous) stamen, part of the male floral organ. The typical anther is bilocular, i.e. it consists of two thecae. Each theca contains two microsporangia, also known as pollen sacs. The microsporangia produce the microspores, which for seed plants are known as pollen grains.
If the anther is cut perpendicular to its axis, it is observed that each anther contains one or two pollen sacs extending along its entire length. [18] [14] After the maturation of the pollen grains, dehiscence or opening of the anther occurs to let the pollen out. The tissue responsible is called endothecium.
A typical anther contains four microsporangia. The microsporangia form sacs or pockets (locules) in the anther (anther sacs or pollen sacs). The two separate locules on each side of an anther may fuse into a single locule. Each microsporangium is lined with a nutritive tissue layer called the tapetum and initially contains diploid pollen mother ...
Sectional organization of spinal cord. The spinal cord is the main pathway for information connecting the brain and peripheral nervous system. [3] [4] Much shorter than its protecting spinal column, the human spinal cord originates in the brainstem, passes through the foramen magnum, and continues through to the conus medullaris near the second lumbar vertebra before terminating in a fibrous ...
The central canal (also known as spinal foramen or ependymal canal) is the cerebrospinal fluid-filled space that runs through the spinal cord. [1] The central canal lies below and is connected to the ventricular system of the brain, from which it receives cerebrospinal fluid, and shares the same ependymal lining. The central canal helps to ...
The ventricular system is continuous with the central canal of the spinal cord from the fourth ventricle, [3] allowing for the flow of CSF to circulate. [ 3 ] [ 4 ] All of the ventricular system and the central canal of the spinal cord are lined with ependyma , a specialised form of epithelium connected by tight junctions that make up the blood ...
The sterile cells may form a central support structure or surround the spermatogenous tissue as a protective jacket. The spermatogenous cells give rise to spermatids via mitotic cell division. In some bryophytes, the antheridium is borne on an antheridiophore, a stalk-like structure that carries the antheridium at its apex. [3]
The cerebral aqueduct, as other parts of the ventricular system of the brain, develops from the central canal of the neural tube, and it originates from the portion of the neural tube that is present in the developing mesencephalon, hence the name "mesencephalic duct."