What is the Difference Between Spermiogenesis and Spermiation

The main difference between spermiogenesis and spermiation is that spermiogenesis is responsible for the formation of spermatozoa whereas spermiation is responsible for the release of spermatozoa from Sertoli cells.

Spermiogenesis and spermiation are two processes that occur in spermatogenesis. Generally, spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testis.              

Key Areas Covered

1. What is Spermiogenesis
     – Definition, Structure, Function
2. What is Spermiation
     – Definition, Structure, Function
3. Similarities – Spermiogenesis and Spermiation
     – Outline of Common Features
4. Difference Between Spermiogenesis and Spermiation
     – Comparison of Key Differences

Key Terms                                                                                                                  

Spermiation, Spermiogenesis, Spermiohistogenesis

What is Spermiogenesis

Normally, spermiogenesis is the production of mature, motile spermatozoa from the spermatids. Spermatids are small, less circular cells. Spermatogenesis is also called spermiohistogenesis. It occurs in the seminiferous tubules of the testes. 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 increases in the Golgi phase. One end of the spermatids becomes the head region. The Golgi apparatus then 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.

Figure 1: Spermatogenesis

Furthermore, during the cap phase, the acrosomal cap is produced by the enclosing of the nucleus by the Golgi apparatus. Generally, the elongation of one of the centrioles in the cell produces the tail of the spermatozoon. The tails of the spermatozoa point toward the center of the lumen. Then, the excess cytoplasm is phagocytized by the Sertoli’s cells during the maturation of the spermatozoa. In general, spermiation is the release of 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.

What is Spermiation

Spermiation is the process by which mature spermatids release from the supporting somatic Sertoli cells into the lumen of the seminiferous tubules. Generally, the process of spermiation takes place over several days at the seminiferous epithelium apical edge. At the same time, mature spermatids undergo several discrete steps, such as remodeling of the head and the cytoplasm of the spermatids, specialized adhesion structures removal, and finally, spermatid disengagement from Sertoli cells. Later, mature spermatids transport into the epididymis.

Figure 2: Sperm

Moreover, after the release of spermatids into the lumen of the seminiferous tubules, the remaining cytoplasm serves as the residual body. However, Sertoli cells phagocyte the residual body. Moreover, the main goal of spermiation is to release spermatids from Sertoli cells. Therefore, spermatids undergo extensive remodeling and reconstruction to produce a spermatozoon.

Similarities Between Spermiogenesis and Spermiation

• Spermiogenesis and spermiation are two types of processes that occur during spermatogenesis.
• Their main function is to develop haploid spermatozoa from germ cells.
• Moreover, both occur inside the seminiferous tubules of the testis.
• The cells that undergo these processes are haploid and contain 23 chromosomes.

Difference Between Spermiogenesis and Spermiation

Definition

Spermiogenesis refers to the process by which haploid round spermatids complete an extraordinary series of events to become streamlined spermatozoa capable of motility, while spermiation refers to the process by which mature spermatids are released from the supporting somatic Sertoli cells into the lumen of the seminiferous tubule.

Importance

Spermiogenesis is responsible for the formation of spermatozoa, while spermiation is responsible for the release of spermatozoa from Sertoli cells.

Occurrence

While spermiogenesis occurs after spermatidogenesis, spermiation occurs after spermiogenesis.

Occurs in

Spermiogenesis occurs in four spermatids, while spermiation occurs in four functional spermatozoids.

Conclusion                                                      

In brief, spermiogenesis and spermiation are two types of processes that occur during spermatogenesis; the process of formation of haploid spermatozoa from germ cells. Generally, spermatidogenesis is the process of formation of spermatozoa in four spermatids. It occurs after spermatidogenesis. On the other hand, spermiation is the process of releasing spermatozoa from Sertoli cells. It occurs after spermiogenesis in four functional spermatozoids. Therefore, the main difference between spermiogenesis and spermiation is the process that occurs in each step of spermatogenesis.                            

References:                

1. O’Donnell L. Mechanisms of spermiogenesis and spermiation and how they are disturbed. Spermatogenesis. 2015 Jan 26;4(2):e979623. doi: 10.4161/21565562.2014.979623. PMID: 26413397; PMCID: PMC4581055.
2. O’Donnell L, Nicholls PK, O’Bryan MK, McLachlan RI, Stanton PG. Spermiation: The process of sperm release. Spermatogenesis. 2011 Jan;1(1):14-35. doi: 10.4161/spmg.1.1.14525. PMID: 21866274; PMCID: PMC3158646.

Image Courtesy:

1. “Figure 28 01 04” By OpenStax College – Own work (CC By 3.0) via Commons Wikimedia
2. “Simplified spermatozoon diagram” By   Mariana Ruiz – Own Work (Public Domain) via Commons Wikimedia