Last Updated on December 30, 2020 by Sagar Aryal
Spermatogenesis is the process of formation of mature sperm cells through a series of mitotic and meiotic divisions along with metamorphic changes in the immature sperm cell.
- It is the male version of gametogenesis which results in the formation of mature male gametes.
- Spermatogenesis requires optimal conditions to occur and is essential for sexual reproduction.
- The complete process of spermatogenesis occurs in different stages that take place in different structures within the male reproductive system.
- It begins in the seminiferous tubules within testes and then continues into the epididymis where maturation of the male gamete occurs, and they are further stored under ejaculation.
- Spermatogenesis begins in males after puberty, and it is continued throughout life. Even though sperms are continuously being formed in the testes, not all areas of testes can form sperm at the same time.
- Sperms in different stages of their development can be found in the testes.
- It begins with a primary spermatocyte that undergoes multiple changes to develop into a motile and matured sperm cell.
- It takes as long as 74 days for an immature germ cell to develop into a mature male gamete, and during that time, there are many intermittent resting stages.
- One primary spermatocyte results in four functional spermatozoa after the process of meiosis, each of which develops separately into a sperm cell.
- The process of spermatogenesis is completed through the following three stages; spermatocytogenesis, spermatidogenesis, and spermiogenesis.
- All of these stages are performed within the testes until the spermatozoa formed finally reach the epididymis and gain motility.
- Human sperm is a motile cell divided into a head, body, and a long tail. The head consists of acrosomes that secrete enzymes and helps in the entry of sperm inside an ovum.
- The overall process of spermatogenesis is regulated by various glands and their products. The luteinizing hormone by the pituitary gland regulates the formation of sperm and the production of testosterone in the male reproductive system.
- The follicle-stimulating hormone, secreted by the pituitary and the testes together regulate the overall process of spermatogenesis.
- The hormone testosterone is responsible for the activation of genes coding for the male gametes, and it also provides nutrients to the sperm cell during its development.
- The process of spermatogenesis is the basis for sexual reproduction which permits genetic recombination, resulting in genetic variation among the species.
Oogenesis is the process of formation of female gamete or ovum through a series of mitotic and meiotic divisions occurring in the female reproductive system.
- It is the female version of gametogenesis which results in the formation of mature male gametes.
- The process of oogenesis starts pre-natally, i.e. before the birth of the female child. It begins about 8-20 weeks after the fetus has begun to grow and goes on until the birth of the child.
- Thus, a newborn female child already has all the egg cells that are to be released from the ovaries during the reproductive life of the female. These cells are termed primary ova.
- The primary ova remain dormant until ovulation and become matured afterward. Some of these cells take as long as 40 years to mature while some never reach maturation.
- The reproductive life of a female is characterized by the monthly periodic changes that occur in the release of sexual hormones as well as changes in the structure of ovaries as well as other sexual organs, called the menstrual cycle.
- The process of oogenesis is described by the ovarian cycle, which is involved in the formation and maturation of female gamete.
- The overall process of oogenesis is divided into three stages; the follicular phase, the ovulation phase, and the luteal phase.
- It begins with the release of follicle-stimulating hormone and luteinizing hormone that causes the cells of the ovary to form primary follicles.
- These follicles then undergo mitotic and meiotic divisions, causing the cell to divide into two larger secondary oocytes and a smaller polar body.
- The secondary oocyte then releases the ovum that moves around the ovary until fertilization. If fertilization doesn’t occur, the cell degenerates into a corpus luteum and is removed from the body during the menstrual cycle.
- The ovum formed is non-motile and remains in the fallopian tube to be fertilized by the sperm. An ovum is an oval structure that contains yolk or plasma that provides nutrients to the cell.
- The process of oogenesis only continues till menopause after which the ovary ceases to form primary oocytes.
- Like spermatogenesis, oogenesis is also controlled by the hormones of the pituitary gland. Besides, the corpus luteum also releases progesterone hormone to regulate the process of menstruation.
- Oogenesis is a biologically vital process that ensures sexual reproduction in animals. It is responsible for the transfer of half of the chromosomes to be introduced into the newborn.
Key Differences (Spermatogenesis vs Oogenesis)
Basis for comparison
|Definition||Spermatogenesis is the process of formation of mature sperm cells through a series of mitotic and meiotic divisions along with metamorphic changes in the immature sperm cell.||Oogenesis is the process of formation of female gamete or ovum through a series of mitotic and meiotic divisions occurring in the female reproductive system.|
|Nature of the process||It is the male version of gametogenesis which results in the formation of mature male gametes.||It is the female version of gametogenesis which results in the formation of mature male gametes.|
|Stages||The process of spermatogenesis is completed through the following three stages; spermatocytogenesis, spermatidogenesis, and spermiogenesis.||The overall process of oogenesis is divided into three stages; the follicular phase, the ovulation phase, and the luteal phase.|
|Occurs in||The overall process of spermatogenesis occurs in the testes until the sperm moves to the epididymis and gains motility.||The overall process of oogenesis occurs in the ovary until the mature ovum moves to the fallopian tube.|
|Continuity of the process||Spermatogenesis is a continuous process that begins with puberty and continuous until death.||The early stages of oogenesis begin in the fetal stage while the rest continue after puberty till menopause.|
|Occurrence||Spermatogenesis occurs continuously, and all spermatogonia undergo meiosis, producing sperms all the time.||Oogenesis occurs for one egg cell at a time, and some cells might require many years to reach maturation.|
|Rate of production||Spermatogenesis forms millions of sperms every day.||Oogenesis releases one ovum per month.|
|Develops from||The male gamete develops from the germinal epithelium of the seminiferous tubules of the testes.||The female gamete develops from the germinal epithelium lining the ovary.|
|Starting cell||The starting cell during spermatogenesis is the primary spermatocyte.||The starting cell during oogenesis is the primary oocyte.|
|Functional cell produced from division||The meiotic division of primary spermatocyte results in four spermatids, each of which develops into a sperm cell.||The meiotic division of primary oocyte only forms a single functional secondary oocyte.|
|Cytogenesis||Cytogenesis in spermatogenesis forms two equal cells.||Cytogenesis in oogenesis forms two unequal cells; larger secondary oocyte and a smaller polar body.|
|Sertoli cells||Sertoli cells are found in the testes that provide nourishment to the developing male gamete.||Sertoli cells are not found in the ovary, and the nourishment to the female gamete is provided by the yolk present around the ovum.|
|Growth phase||The growth phase during spermatogenesis is shorter than in oogenesis.||The growth phase during oogenesis is longer than in spermatogenesis.|
|Resting phase||There is no resting phase during the spermatogenesis process.||The resting phase occurs during oogenesis from the embryonic stage till puberty.|
|Size of the gametes||The male gametes formed after spermatogenesis are smaller in size than the female gametes.||The female gametes formed after oogenesis are larger in size than the male gametes.|
|Motility of the gamete||The male gamete formed is motile.||The female gamete formed is non-motile.|
|Nuclear condensation||Nuclear condensation can be seen in a male gamete.||Nuclear condensation doesn’t take place in the ovum.|
|Food preservation||The male gamete stores less amount of food within itself.||The female gamete stores a lot more food within itself.|
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