Tojássejtek

Tojássejtek, also known as oocytes or egg cells, are the female reproductive cells in sexually reproducing organisms. They are produced by the female gonads, the ovaries. Tojássejtek are large, non-motile cells that contain the female's genetic material, half of which will be passed on to an offspring.

The development of tojássejtek, a process called oogenesis, begins before birth in mammals. In humans, a female is born with all the oocytes she will ever have, arrested in a specific stage of meiosis. Puberty triggers the maturation of these oocytes, with typically one maturing and being released from the ovary each menstrual cycle. This release is called ovulation.

A tojássejt is a specialized cell designed for fertilization. It is surrounded by protective layers, including the zona pellucida and corona radiata, which play roles in sperm binding and the prevention of polyspermy (fertilization by multiple sperm). Upon fertilization by a sperm cell, the tojássejt completes meiosis and fuses its nucleus with the sperm's nucleus, forming a zygote, the first cell of a new individual. The cytoplasm of the tojássejt also contains nutrients essential for the early development of the embryo. The size and structure of tojássejtek can vary significantly between different species, reflecting diverse reproductive strategies.