Sexual reproduction in fungi involves the fusion of two compatible nuclei or sex cells (i.e., gametes) of the opposite sex at a definite stage in the life history of fungus.
The sex organ that produces gametes is called gametangia.
The gametangia of fungi are unicellular and not surrounded by a sterile jacket.
In fungi, there is a gradual reduction in sexuality from the lower to the higher fungi.
Gametangial contact:
The two gametangia come close to each other, but do not fuse.
The male gametangium sends a tubular outgrowth, called a fertilization tube, through which the non-motile male gamete or male nucleus migrates into the female gametangium.