Formation of Ascospores Essay

In a typical ascomycotina, pyronema for example, sexual reproduction is by gametangial contact invoving the ascogonium ( female organ) and antherridium (male organ). Ascus and ascopores are results of sexual reproduction . the female and male organs aare produced by the mycelium. A trichogyne is also produced which joins the antheridium to the ascogonium. The content of the antheridium passes into the ascogonium through the trichogyne. The ascogonium and antheridiumare multinucleate. After the contact have pass into the ascogoniu, the trichogyne disintergrate and the male organ becomes empty and later withers.

The nuclei from two sources pair up in the ascogenous but donot fusend this is called DIKARYOTISATION. From, the female organ the ascogenous hyphae are produced. These ascogenous hyphae now contains the nuclei which are in poairs.

The uclei pairs undergo conjugate division or mitosis and septan develop to cut the ascogenous hyphae into cells. The tip of the ascogenous hyphae elongate and bends into a hookmn which is called a CROZIER.

The two nuclei at the tip in the crozier divide conjugately 9mitosis) as a result of which four nuclei are produced. This is done in such a way at which two nuclei are at the bend of the hook, one towards the tips and the other one near the septum to the mycelium.

Then, new septa arev formed to divide the cells int three. The three cells are binucleate crook cell, uninucleate tip cell and a uninucleate basal cell. The binucleate crook cell would develop into the ascus and is called Ascus mother cells. The two nuclei in the ascus mother cell fuse to form one diploid nucleus. The cell that contains the diploid nucleus elongate. The diploid nucleus under goes meiosis ( reduction division) to give rise to four haploid nuclei. The four nuclei divide by mitosis to give rise to eight nuclei and these nuclei forms the nuclei of the eight ascospores which are contained in the ascus. Thus, the ascus and ascospores are formed.

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