Compare the processes of spermatogenesis and oogenesis, indicate the similarities and differences.

Similarity:
– They are the processes of gametogenesis – the formation and development of germ cells (gametes), are divided into several periods, proceeding in a similar way.
– The first stage is the breeding season. Diploid gamete precursors are repeatedly divided by mitosis, as a result of which their number increases significantly.
– The second stage is the growth period. Spermatogonia (oogonia) increase in size and become first-order spermatocytes (oocytes).
– The third stage is the ripening period. Meiosis occurs, as a result of which, from each first-order spermatocyte (oocyte) containing the 2n4c set, four haploid daughter cells are formed (1n1c set).

Differences:
– As a result of spermatogenesis, mobile male germ cells — spermatozoa — are formed, as a result of oogenesis, immobile female gametes — eggs — are formed. Typically, sperm in the male body is formed many times more than the eggs in the female.
– In spermatogenesis, the maturation period is followed by the period of sperm formation; in oogenesis, the formation period is absent. Thus, spermatogenesis includes four periods, and oogenesis includes three.
– Spermatogenesis in male mammals begins with puberty. Oogenesis in female mammals begins even before birth.
– During the period of growth of spermatogonia increase slightly in size, and the size of oogonia increases significantly.
– During spermatogenesis, meiosis leads to the formation of four identical daughter cells, spermatids, from one first-order spermatocyte. During oogenesis, nonuniform meiotic division of the first order oocyte occurs, as a result of which one large cell with a supply of nutrients (egg) and three small polar bodies are formed.