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The outer layer of cells of an apical meristem. This is known as the tunica. In biology, a tunica (/ ˈ t (j) uː n ɪ k ə /, [1] UK: / ˈ tʃ uː n ɪ k ə /; pl.: tunicae) is a layer, coat, sheath, or similar covering. The word came to English from the Neo-Latin of science and medicine.
The tunica albuginea is a dense, [1] [2] blue-white [3] layer of fibrous tissue surrounding the testis. [ 1 ] [ 4 ] It is the middle of three envelopes forming the capsule of the testis; it is deep to the visceral layer of tunica vaginalis , and superficial to the tunica vasculosa testis (vascular layer of testis) .
Stromal cells associated with maturing follicles may acquire endocrine function and secrete estrogens. The entire ovarian stroma is highly vascular. [1] On the surface of the organ this tissue is much condensed, and forms a layer (tunica albuginea) composed of short connective-tissue fibers, with fusiform cells between them.
In both gymnosperms and angiosperms, the young plant contained in the seed, begins as a developing egg-cell formed after fertilization (sometimes without fertilization in a process called apomixis) and becomes a plant embryo. This embryonic condition also occurs in the buds that form on stems. The buds have tissue that has differentiated but ...
The tunica albuginea is composed of short connective tissue fibers. It is located immediately inside the surface epithelium (previously known as germinal epithelium) which is continuous with the peritoneum. It is non-vascularised. [1] It is thinner than the tunica albuginea of the testis, and its thickness varies across the ovary. [1]
The embryological origin of granulosa cells remains controversial. In the 1970s, evidence emerged that the first cells to make contact with the oogonia were of mesonephric origin. It was suggested that mesonephric cells already closely associated with the oogonia proliferated throughout development to form the granulosa cell layer. [2] [3] [4]
Structure of a plant cell. Plant cells are the cells present in green plants, photosynthetic eukaryotes of the kingdom Plantae.Their distinctive features include primary cell walls containing cellulose, hemicelluloses and pectin, the presence of plastids with the capability to perform photosynthesis and store starch, a large vacuole that regulates turgor pressure, the absence of flagella or ...
Cumulus oophorus are the cells surrounding corona radiata, and are the cells between corona radiata and follicular antrum. Its main purpose in many animals is to supply vital proteins to the cell. [ citation needed ] It is formed by follicle cells adhering to the oocyte before it leaves the ovarian follicle , and originates from the squamous ...