Gametogenesis is the biological process of forming gametes. In males, this process produces sperm, while in females it produces the ovum (egg). Formation of sperm is spermatogenesis process, and the formation of ovum is oogenesis process.
In humans, we refer to the female gamete as the ovum before fertilization. We use the term egg only after fertilization.
In this blog, we will discuss spermatogenesis step by step.
What is Spermatogenesis?
Definition: Spermatogenesis is the process of sperm cell formation that takes place in the seminiferous tubules of the testes. It includes stages like multiplication, growth, maturation, spermiogenesis, and spermiation.
Location:
It takes place in the seminiferous tubules of the testes.
Stages of Spermatogenesis (Step by Step)
The stages of spermatogenesis are divided into multiplication, growth, maturation, spermiogenesis, and spermiation. A spermatogenesis diagram can help you visualize the steps clearly.
1. Multiplication Stage
- Germ cells in the seminiferous tubules undergo mitosis.
- They form diploid cells called spermatogonia (2n).
- Some spermatogonia remain as Type A (stem cells) for renewal, while others become Type B spermatogonia, which move to the next stage.
2. Growth Stage
- Type B spermatogonia increase in size and absorb nutrients.
- These enlarged cells are called Primary Spermatocytes (2n).
3. Maturation Stage
- Meiosis I: Each primary spermatocyte (2n) undergoes reduction division to form Secondary Spermatocytes (n).
- Meiosis II: Each secondary spermatocyte divides again, producing Spermatids (n).
- Spermatids are haploid, circular, and non-motile at this stage.
4. Spermiogenesis
This is the transformation of non-motile spermatids into mature, motile sperm. Major changes include:
- Condensation of the nucleus (retaining only DNA).
- Development of the acrosome from the Golgi apparatus (helps in penetrating the ovum).
- Mitochondria arrange spirally in the midpiece to provide energy.
- Cytoplasm is reduced.
- Tail formation enables motility.
5. Spermiation
- The final step, where mature sperm are released from the Sertoli cells into the lumen of seminiferous tubules.
- At this point, sperms are haploid (23 chromosomes), motile, and functional.
Summary
- Germ cells (2n) → Spermatogonia (2n)
- Type B Spermatogonia (2n) → Primary Spermatocytes (2n)
- Meiosis I → Secondary Spermatocytes (n)
- Meiosis II → Spermatids (n)
- Spermiogenesis → Mature Sperm (n)
- Spermiation → Release into seminiferous tubule lumen
Difference Between Spermatogenesis and Spermiation
- Spermatogenesis is the entire process of formation of sperm from diploid germ cells. It starts with spermatogonia and ends with the production of mature sperm cells.
- Spermiation is the final step of spermatogenesis, where the mature sperms are released from the Sertoli cells into the lumen of the seminiferous tubules.
👉 In short:
- Spermatogenesis = Formation process
- Spermiation = Release step
Difference Between Spermatogenesis and Oogenesis
- Spermatogenesis occurs in males and produces millions of motile sperms daily.
- Oogenesis occurs in females and produces a single large ovum during each menstrual cycle.
Thus, while spermatogenesis ensures continuous sperm production, oogenesis produces limited gametes in a lifetime.
Key Points to Remember
- Spermatogenesis begins at puberty.
- The process ensures continuous production of sperm throughout a male’s reproductive life.
- Mature sperm have three distinct regions: Head, Midpiece, and Tail.