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  2. Pollen - Wikipedia

    en.wikipedia.org/wiki/Pollen

    Pollen itself is not the male gamete. [4] It is a gametophyte, something that could be considered an entire organism, which then produces the male gamete.Each pollen grain contains vegetative (non-reproductive) cells (only a single cell in most flowering plants but several in other seed plants) and a generative (reproductive) cell.

  3. Type I hypersensitivity - Wikipedia

    en.wikipedia.org/wiki/Type_I_hypersensitivity

    In type I hypersensitivity, B cells are stimulated (by CD4 + T h 2 cells) to produce IgE antibodies specific to an antigen. The difference between a normal infectious immune response and a type 1 hypersensitivity response is that in type 1 hypersensitivity, the antibody is IgE instead of IgA, IgG, or IgM.

  4. Pollination - Wikipedia

    en.wikipedia.org/wiki/Pollination

    The pollen enters a pollen chamber close to the nucellus, and there it may wait for a year before it germinates and forms a pollen tube that grows through the wall of the megasporangium (=nucellus) where fertilisation takes place. During this time, the megaspore mother cell divides by meiosis to form four haploid cells, three of which degenerate.

  5. Tapetum (botany) - Wikipedia

    en.wikipedia.org/wiki/Tapetum_(botany)

    Tapetum is important for the nutrition and development of pollen grains and a source of precursors for the pollen coat. [1] The cells are usually bigger and normally have more than one nucleus per cell. As the sporogenous cells undergo mitosis, the nuclei of tapetal cells also divide.

  6. Allergy - Wikipedia

    en.wikipedia.org/wiki/Allergy

    In the initial stages of allergy, a type I hypersensitivity reaction against an allergen encountered for the first time and presented by a professional antigen-presenting cell causes a response in a type of immune cell called a T H 2 lymphocyte, a subset of T cells that produce a cytokine called interleukin-4 (IL-4).

  7. 46% of Americans have seasonal allergies — and 22% have ...

    www.aol.com/lifestyle/46-americans-seasonal...

    Which medications can help, according to experts. To help alleviate these symptoms, 72% of respondents said they take over-the-counter or prescription allergy medication.

  8. Allergen - Wikipedia

    en.wikipedia.org/wiki/Allergen

    An allergen is an otherwise harmless substance that triggers an allergic reaction in sensitive individuals by stimulating an immune response.. In technical terms, an allergen is an antigen that is capable of stimulating a type-I hypersensitivity reaction in atopic individuals through immunoglobulin E (IgE) responses. [1]

  9. Theca - Wikipedia

    en.wikipedia.org/wiki/Theca

    The tissue between the locules and the cells is called the connective and the parenchyma. Both pollen sacs are separated by the stomium. When the anther is dehiscing, it opens at the stomium. The outer cells of the theca form the epidermis. Below the epidermis, the somatic cells form the tapetum. These support the development of microspores ...