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 ?
A prior study suggested the use of an intraperitoneal injection of oxytocin (1/800 ILJ) immediately prior to non-surgical artificial insemination of Wistar rats with frozen-thawed spermatozoids to increase the number of pups at birth, suggesting oxytocin induces uterine contractions that might play an important role in spermatozoid transport.
elongatus, where lysed spermatozoids were observed close to lipid-like substances and phagocytes (Le Pennec and Beninger, 1997).
where TA is the total number (in millions) of spermatozoids in the whole ejaculate, A is the percentage of active spermatozoids, and NK the percentage of normokinetic spermatozoids.
applies to the spermatozoids, but these are formed simultaneously
The percentage of normal spermatozoids was significantly higher in farmed than in feral males.
Tandem reduction-chloroallylboration of esters: asymmetric synthesis of lamoxirene, the spermatozoid releasing and attracting pheromone of the Laminariales (Phaeophyceae).
Follicle walls break and a large diffuse spermatozoid mass, in process of being expelled, can be observed.
The released gametes, normally spermatozoids, occurred 90 min after the thermal stimulus and the addition of sperm accelerated the spawning process.
Dorier A (1951) Conservation of the vitality and fertile power of the spermatozoids of rainbow trout.
From these characteristics the following sexual maturity states were established: immature males, individuals lacking spermatids or spermatozoids in the testis; submature males, voles with few spermatozoids and spermatids in the testis and without or with a very scarce number of spermatozoids in the epididymis; and mature males, specimens with a large amount of spermatozoids in both structures.
The apical portion of the epithelial cells has spermatozoids adhered by their heads with their flagella directed towards the lumen.