**Oogenesis** and **spermatogenesis** are the processes by which female and male gametes (eggs and sperm) are produced, respectively. Both processes involve cell division and meiosis, but there are some key differences between the two.
**Oogenesis** begins in the prenatal period, when oogonia (female germ cells) are formed in the ovaries. Oogonia divide mitotically until puberty, at which point they begin to undergo meiosis. However, meiosis in oogonia is arrested at the prophase I stage and remains dormant until ovulation. At ovulation, one oogonium completes meiosis I and meiosis II, resulting in the formation of one mature egg and three polar bodies. The polar bodies are small cells that degenerate and do not contribute to the formation of the embryo.
**Spermatogenesis** begins in the testes at puberty. Spermatogonia (male germ cells) divide mitotically to produce primary spermatocytes. Primary spermatocytes undergo meiosis I to produce secondary spermatocytes. Secondary spermatocytes undergo meiosis II to produce four spermatids. Spermatids then differentiate into mature sperm.
The main differences between oogenesis and spermatogenesis are as follows:
| **Timing of meiosis** | Meiosis I begins in the prenatal period and Meiosis II begins at ovulation | Meiosis I begins at puberty and Meiosis II begins after meiosis I |
| **Number of gametes produced** | One mature egg and three polar bodies are produced from each oogonium | Four mature sperm are produced from each spermatogonium |
| **Site of gametogenesis** | Ovaries | Testes |
**External fertilization** occurs when the sperm and egg fuse outside of the female body. This is the most common form of fertilization in fish and amphibians.
**Internal fertilization** occurs when the sperm and egg fuse inside of the female body. This is the most common form of fertilization in mammals, birds, and reptiles.
The main difference between external and internal fertilization is the location of fertilization. External fertilization occurs outside of the female body, while internal fertilization occurs inside of the female body.
**Morula** is the stage of embryonic development that occurs after the fertilized egg has undergone several rounds of cell division. The morula is a solid ball of cells that contains about 32 cells.
**Blastula** is the stage of embryonic development that occurs after the morula has undergone a process called cavitation. Cavitation is the formation of a fluid-filled cavity inside of the morula. The blastula is a hollow ball of cells that contains a fluid-filled cavity called the blastocoel.
The main difference between the morula and the blastula is the presence of a blastocoel. The morula is a solid ball of cells, while the blastula is a hollow ball of cells that contains a blastocoel.
Answers & Comments
Answer:
**Oogenesis** and **spermatogenesis** are the processes by which female and male gametes (eggs and sperm) are produced, respectively. Both processes involve cell division and meiosis, but there are some key differences between the two.
**Oogenesis** begins in the prenatal period, when oogonia (female germ cells) are formed in the ovaries. Oogonia divide mitotically until puberty, at which point they begin to undergo meiosis. However, meiosis in oogonia is arrested at the prophase I stage and remains dormant until ovulation. At ovulation, one oogonium completes meiosis I and meiosis II, resulting in the formation of one mature egg and three polar bodies. The polar bodies are small cells that degenerate and do not contribute to the formation of the embryo.
**Spermatogenesis** begins in the testes at puberty. Spermatogonia (male germ cells) divide mitotically to produce primary spermatocytes. Primary spermatocytes undergo meiosis I to produce secondary spermatocytes. Secondary spermatocytes undergo meiosis II to produce four spermatids. Spermatids then differentiate into mature sperm.
The main differences between oogenesis and spermatogenesis are as follows:
| **Characteristic** | **Oogenesis** | **Spermatogenesis** |
|---|---|---|
| **Timing of meiosis** | Meiosis I begins in the prenatal period and Meiosis II begins at ovulation | Meiosis I begins at puberty and Meiosis II begins after meiosis I |
| **Number of gametes produced** | One mature egg and three polar bodies are produced from each oogonium | Four mature sperm are produced from each spermatogonium |
| **Site of gametogenesis** | Ovaries | Testes |
**External fertilization** occurs when the sperm and egg fuse outside of the female body. This is the most common form of fertilization in fish and amphibians.
**Internal fertilization** occurs when the sperm and egg fuse inside of the female body. This is the most common form of fertilization in mammals, birds, and reptiles.
The main difference between external and internal fertilization is the location of fertilization. External fertilization occurs outside of the female body, while internal fertilization occurs inside of the female body.
**Morula** is the stage of embryonic development that occurs after the fertilized egg has undergone several rounds of cell division. The morula is a solid ball of cells that contains about 32 cells.
**Blastula** is the stage of embryonic development that occurs after the morula has undergone a process called cavitation. Cavitation is the formation of a fluid-filled cavity inside of the morula. The blastula is a hollow ball of cells that contains a fluid-filled cavity called the blastocoel.
The main difference between the morula and the blastula is the presence of a blastocoel. The morula is a solid ball of cells, while the blastula is a hollow ball of cells that contains a blastocoel.
I hope this helps!