Difference Between Spermatogenesis and Spermiogenesis

Main Difference – Spermatogenesis vs Spermiogenesis

Spermatogenesis and spermiogenesis are two stages that occur during the formation of sperms. Sperms are the male gametes produced in the seminiferous tubules of the testes. The main difference between spermatogenesis and spermiogenesis is that spermatogenesis is the formation of sperm cells whereas spermiogenesis is the maturation of the spermatids into sperm cells. This means spermatogenesis is the complete process of the production of the sperm cells from the cells of the germinal epithelium of males. Spermiogenesis, on the other hand, is the final differentiation and maturation process of the spermatids into sperm cells.

Key Areas Covered

1. What is Spermatogenesis
      – Definition, Stages, Types
2. What is Spermiogenesis
      – Definition, Phases
3. What are the Similarities Between Spermatogenesis and Spermiogenesis
      – Outline of Common Features
4. What is the Difference Between Spermatogenesis and Spermiogenesis
      – Comparison of Key Differences

Key Terms: Primary Spermatocytes, Secondary Spermatocytes, Seminiferous Tubules, Sertoli’s Cells, Spermatids, Spermatogenesis, Spermatozoa, Spermiation, Spermiogenesis, Spermiohistogenesis

What is Spermatogenesis

Spermatogenesis is the process of forming motile spermatozoa from spermatogonium. This process occurs in the basement membrane of the seminiferous tubules of the testes. It takes approximately 64 days to complete the spermatogenesis. The whole process can be subdivided into four stages. The first stage is the mitosis of the spermatogonia. This produces primary spermatocytes. It takes around 16 days to complete mitosis. The second stage, meiosis 1 in which the secondary spermatocytes are produced from the primary spermatocytes, takes about 24 days. The meiosis 2 is the third stage of spermatogenesis, which gives rise to the spermatids. This stage is completed in few hours. The spermiogenesis is the fourth stage where motile spermatozoa are produced and takes 24 days. 

Figure 1: Spermatogenesis

Two types of spermatogonia can be identified in the basal layer of the germinal epithelium. Type A spermatogonia divide by mitosis to increase the cell number. This is called homonymous division. Type A spermatogonia maintain the spermatogonia population. Spermatogenesis starts with the heteronymous cell division, which produces a second group of type A cells, which are attached together by the thin bridges of the cytoplasm. Type B spermatogonia are produced by the mitotic divisions of type A spermatogonia. The primary spermatocytes are produced by the mitotic divisions of the type B spermatogonia. The spermatids, which are arisen from the secondary spermatocytes, are the smallest type of cells in the germinal epithelium. They are transformed into spermatozoa in a process called spermiogenesis with the assistance of the Sertoli’s cells.

What is Spermiogenesis

Spermiogenesis is the production of mature, motile spermatozoa from the spermatids. The spermatids are small, less circular cells. The spermatogenesis is also called spermiohistogenesis.  It occurs in the seminiferous tubules of the testes. A cross-section of a seminiferous tubule is shown in figure 2.

Figure 2: Spermatozoa in the Seminiferous Tubule

Spermiogenesis occurs in four phases: Golgi phase, cap phase, the formation of the tail, and the maturation stage. The polarity of the radially symmetric spermatids is increased in the Golgi phase. One end of the spermatids becomes the head region. The Golgi apparatus produces enzymes in the acrosome. The axoneme is also produced from the distal centriole during the Golgi phase. It is a gathering of mitochondria. The condensation of DNA produces transcriptionally inactive chromatin. During the cap phase, the acrosomal cap is produced by the enclosing of the nucleus by the Golgi apparatus. The elongation of one of the centrioles in the cell produces the tail of the spermatozoon. The tails of the spermatozoa point towards the center of the lumen. Then, the excess cytoplasm is phagocytized by the Sertoli’s cells during the maturation of the spermatozoa. Spermiation is the release of the mature spermatozoa into the lumen of the seminiferous tubules. The mature spermatozoa are also called sperm cells. Since their tails are made up of long flagella, spermatozoa are motile.

Similarities Between Spermatogenesis and Spermiogenesis

• Both spermatogenesis and spermiogenesis are responsible for the formation of mature male gametes in humans.
• Both spermatogenesis and spermiogenesis occur in the seminiferous tubules of the testes.

Difference Between Spermatogenesis and Spermiogenesis

Definition

Spermatogenesis: Spermatogenesis is the formation of motile spermatozoa from spermatogonium.

Spermiogenesis: Spermiogenesis is the production of mature spermatozoa from spermatids.

Production

Spermatogenesis: Four functional spermatozoa are produced from a spermatogonium during the spermatogenesis.

Spermiogenesis: A spermatozoon is produced from a spermatid during the spermiogenesis.

Phases

Spermatogenesis: Spermatogenesis consists of a multiplication phase, growth phase, maturation phase, and a differentiation phase.

Spermiogenesis: Spermiogenesis consists of a differentiation process.

Significance

Spermatogenesis: Spermatogenesis is the whole process of the production of mature sperm cells from the primordial germ cells.

Spermiogenesis: Spermiogenesis is the final differentiation phase of the spermatogenesis where mature spermatozoa are produced.

Change in the Genetic Material

Spermatogenesis: Diploid germ cells become haploid gametes during the spermatogenesis.

Spermiogenesis: Spermiogenesis occurs in the haploid cells. Therefore, no change in the amount of genetic material occurs during spermiogenesis.

Number

Spermatogenesis: The number of cells that are capable of differentiating into spermatozoa is increased in the early stages of the spermatogenesis.

Spermiogenesis: No change in the number of cells occurs during spermiogenesis.

Conclusion

Spermatogenesis and spermiogenesis are two processes that are involved in the production of mature sperm cells. Spermatogenesis is the production and the differentiation of the motile spermatozoa cells from the cells of the germinal epithelium of males. Spermiogenesis is the differentiation and the maturation of the spermatids into motile spermatozoa. Spermiogenesis is the final part of the spermatogenesis while spermatogenesis is the complete process of the production of functional, male gametes. The main difference between spermatogenesis and spermiogenesis is the mechanism of each process in the production of the sperm.

Reference:

1.“3.3 Spermatogenesis.” Spermatogenesis, Available here. Accessed 2 Oct. 2017.
2.O’Donnell, Liza. “Mechanisms of spermiogenesis and spermiation and how they are disturbed.” Spermatogenesis, Taylor & Francis, 2014, Available here. Accessed 2 Oct. 2017.

Image Courtesy:

1. “Figure 28 01 04” By OpenStax College – Anatomy & Physiology, Connexions Web site. Available here, Jun 19, 2013. (CC BY 3.0) via Commons Wikimedia
2. “Gray1150” By Henry Vandyke Carter – Henry Gray (1918) Anatomy of the Human Body, Bartleby.com: Gray’s Anatomy, Plate 1150 (Public Domain) via Commons Wikimedia