Identification of Stages of Gamete Development

Gamete Development occurs in the primary sex organs, i.e., testis and ovary in male and female organisms respectively. The process of gamete development i.e., sperms and ovum is termed gametogenesis and involves meiotic cell division. The gamete development in the testis is referred to as spermatogenesis and in the ovary as oogenesis. They exhibit distinct characteristics which can be examined in the transverse section (T.S.) of these organs. In this section, we shall study the identification of stages of gamete development.

Aim

The experiment aims to identify different stages of gamete development as seen in T.S of Testis and Ovary.

Material Requirement

The following are the materials required for the procedure:

1. A compound microscope
2. Permanent slides of T.S. (transverse section) of the Testis and Ovary.
3. Lens-cleaning paper
4. Cleaning fluid

Procedure

The following points are involved in the procedure :

1. Wash hands thoroughly and dry them completely.
2. Use lens cleaning paper and cleaning fluid to clean the slide, the microscope's eye, and the objective lenses.
3. Place the slide on the microscope's stage.
4. Observe different stages of gamete development. Start with lower magnification first and then proceed to higher magnification.

Study of T.S. of Mammalian Testis

The male reproductive organ has two primary structures – a pair of testes as well as some accessory reproductive structures. During adulthood, mammalian testes serve two vital functions. The first is called spermatogenesis, and the second is production of male sex hormones. Testosterone is the primary hormone that males produce in the testis. 

👁 TS-of-Mammalian-Testis

Observation

T.S. of a testis has a dense fibrous tissue covering called tunica albuginea. Under lower magnification, a huge number of seminiferous tubules are observed. The space between seminiferous tubules is occupied with blood vessels and a very specific cell-type known as Leydig’s cell or Interstitial cells. To know more, please refer to the article Testes – Anatomy and Functions. There are five stages of gamete development during spermatogenesis, and the cells are organized in the following order from the outside to the inside:

Spermatogonia → Primary Spermatocytes → Secondary Spermatocytes→ Spermatids → Spermatozoa (sperms)

👁 TS-of-Mammalian-Ovary-

The last stage in gamete development is sperm formation. Most of the sperms have Sertoli cells embedded in them.

Study of T.S. of Mammalian Ovary

In females, every mammalian ovary is a reproductive organ that produces sex cells called ova. In addition to producing sex cells, the ovaries also secrete hormones. Each ovary is made up of an outer cortex that contains follicles, interstitial cells, and oocytes. Additionally, there is an inner medulla that contains blood vessels, nerves and fibrous tissues.

Observation

In order to study of the transverse section of an ovary, the development of the follicles is very important. Following are the key observations:

1. The ovary is a solid organ and is covered by a thick layer of fibrous tissue, also known as tunica albuginea, which is lined with germinal epithelium.
2. The T.S. of the mammalian ovary reveals an ovum surrounded by one or more layers of spherical oval entities known as ovarian follicles.
3. As the ovum grows and matures, the total number of surrounding follicular cell layer rises.
4. The appearance of a cavity known as the antrum occurs in the later stage of follicular development
5. The follicle enlarges and the cavity gets even larger. At this stage, the Graafian follicle is ready to release the ovum. This stage is called ovulation.
6. In the following phase, we observe a Corpus luteum and Corpus albicans, which are characterized by differences from Graafian follicles as well as from one another.

Also Read: Ovarian Follicular Development

The stages of follicle development are listed below:

Primordial follicle → Primary follicle → Secondary follicle → Mature (Graffian) follicle → Corpus luteum. 

Precautions

Following is a list of precautions that should be taken while observing the slides:

• • Make sure to wear gloves in the lab.
• • Use forceps and other tools when working with the organs.
• • Verify if the focus of the microscopic lens is adjusted sufficiently.
• • After the experiment is over, carefully store the slides and clean the microscopic lens.

Also Read,

• Gametogenesis - Spermatogenesis and Oogenesis
• Oogenesis - Definition, Process, and Stages
• Human Reproductive System- Male and Female
• Cell Division