Question

Where are sperm stored previous to ejaculation? Why must sperm spend up to 2 weeks in the epididymis? What is the process of sperm development called?

Answer 1

First question:

The epididymis stores the sperm temporarily prior to ejaculation.

Second question:

Epididymis:

The seminiferous tubules open into a network of tubules called rete testis. The rete testis open into epididymis through the efferent ductules.

Structure:

Epididymis is located on the posterior aspect of the testis. It contains a highly convoluted duct which is about 5 meters in length. The epididymis is divided into three parts: head (the part close to the testis), body, and tail.

Function:

• The function of the epididymis is the storage and maturation of the spermatozoa.
• About 99% of the testicular fluid is reabsorbed in the epididymis and rete testis. Spermatozoa from the tubular fluid and rete testis is transferred to the epididymis almost passively as they are essentially immotile.
• In the epididymis, the spermatozoa acquire the capacity for progressive forward movement and ability to attach to the zona pellucida of ovum and penetrate into it.
• Thus, the sperms obtained directly from the testis are functionally immature, whereas the sperms obtained from the body of the epididymis or further down in the male genital tract are fertile.
• Hence, the storage of sperms in the epididymis is essential for the maturation process for the acquirement of fertility and motility.

Third question:

The process is called spermatogenesis.

Spermatogenesis:

The process of development of male germ cells into spermatozoa is known as spermatogenesis.

Steps of spermatogenesis:

• Mitosis:

The primitive germ cells called spermatogonia undergo mitotic divisions to produce primary spermatocyte. The primary spermatocyte has 46 chromosomes.

• Meiosis:

The primary spermatocyte undergoes two meiotic divisions. The first miotic division forms the secondary spermatocyte (23 chromosomes). The second meiotic division forms the spermatids (23 chromosomes). Normally after undergoing several mitotic and two miotic division is in the process of spermatogenesis, each spermatogonium yields 512 spermatids.

• Spermiogenesis:

The process of development of sperm into mature spermatozoa is called spermiogenesis. Many structural changes occur in the spermatid to form the spermatozoa. the major changes are massive reduction of cytoplasm, elongation of the nucleus, acquirement of acrosomal cap, and formation of middle piece and tail. All these changes occur in the mature sperms to enable them to survive in the acidic vaginal environment.

Spermiation: The process of detachment of the head of spermatozoa and their free release into the luminal fluid is called spermiation.