Spermatozoid


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Spermatozoid

 

(also antherozoid), a male sexual cell of many plants. Spermatozoids with two or more flagella are found in green and brown algae and in some lower fungi, mosses, ferns, horsetails, club mosses, quillworts, selaginellas, Cycadopsida, and ginkgos.

Spermatozoids lack a cellulosic coat and are usually very small, with the exception of those in some Cycadopsida that reach 300 micrometers in diameter and are visible to the naked eye. In spite of their small size, they usually have a large nucleus and a small quantity of cytoplasm. The flagellum is situated at the anterior end of the spermatozoid, in the direction of movement. Movement toward ova is made possible by various chemical substances constituting the female sexual cells and organs.

Most spermatophytes are characterized by the presence of sperm, nonmotile male sexual cells that lack flagella, since fertilization in plants does not depend on a liquid medium.

REFERENCES

See references under .

L. V. DANILOVA

References in periodicals archive ?
The purpose of the bubble is to reduce evaporation of the solution during storage but contamination of the spermatozoid solution with mineral oil is frequently seen upon injection inside the uterus.
Presence of spermatocytes was observed in males, as well as spermatozoids in the spermatic lobes and spermatic sacs (Fig.
For male acini, germinal cells sat within the inner wall of the acinus, with spermatocysts, spermatids, and spermatozoids developing toward the lumen.
The last item lead us to suggest that in spite of the higher proportion in spermatophore weight and spermatozoid count of feral males, the higher percentage of normal spermatozoids in farmed shrimps compensates such inequalities, making farmed males a more reliable source of spermatozoids for female fertilization given their availability and consistency.
The spermatozoid of Microcycas calocoma: Ultrastructure.
Tandem reduction-chloroallylboration of esters: asymmetric synthesis of lamoxirene, the spermatozoid releasing and attracting pheromone of the Laminariales (Phaeophyceae).
Among nonfeeding developers, Abatus cordatus, with a 15-[[micro]meter]-long spermatozoid head and an egg 1300 [[micro]meter] in diameter, has the longest echinoid sperm after Phyllacanthus parvispinus (20 [[micro]meter]; Raff et al., 1990), whose egg is not as large (700 [[micro]meter] in diameter; Mortensen, 1921).
Measured under a light microscope, the spermatozoid head exhibited a length of approximately 5 [micro]m, whereas the tail was approximately 50 [micro]m long.
Follicle walls break and a large diffuse spermatozoid mass, in process of being expelled, can be observed.