Key Steps to Recognize Each Gamete Development Stage
Mammalian ovary is a reproductive organ in females inside which sex cells like eggs or ova are produced. The ovaries come in pairs and prudence hormones in addition to sex cells. The male reproductive organ has two primary structures. A pair of testes and some accessory reproductive structures. Adult mammalian testes perform two essential functions.
There are sperms present in the body of a male organism while the female organisms consist of ovaries that are developed. Both of these gametes help in the production of the zygote which then turns into the baby of that particular organism. But learning the stages that are involved in the gamete development is very important in order to understand the functioning that is involved. The Identification of Stages of Gamete Development - Biology Practicals helps students to learn about the same and understand how it works before actually learning more about the zygote. The overall growth and development of the testes and ovaries are governed by the urogenital system. The urinary system and the genital system are two completely different systems that are independent of each other.
Difference Between a Gamete and a Gametophyte:
The difference between a gamete and a gametophyte can be provided as follows:
Practical Identification of Stages of Gamete Development
Study of T.S. of Mammalian Ovary
Every mammalian ovary is a reproductive organ in females inside which sex cells like eggs or ova are produced. The ovaries come in pairs and prudence hormones in addition to sex cells. These hormones trigger the process of reproduction in females. While ovaries are the primary reproductive organs in females, the male counterparts have a primary reproductive organ known as testes. Each ovary consists of an outer cortex that contains follicles, interstitial cells, and oocytes. There is also an inner medulla which contains fibrous tissues, blood vessels and nerves. The T.S.of the mammalian ovary or transverse section of the ovary is studied and identified through experimental slides.
T.S. of Mammalian Ovary Under Microscope
Aim: To study and identify the T.S. Of mammalian ovaries under permanent slides.
Apparatus: Permanent slides of T.S. or transverse section of the ovary, microscope
Observation: Any mammalian ovary has a solid structure to it and is bounded by epithelium along with a thick layer of fibrous tissue, also known as tunica albuginea. The ovary has an outer cortex and an inner medulla. The T.S.of the mammalian ovary reveals the rounded oval bodies, also known as ovarian follicles.
The follicles develop from stage 1 to Graffian follicles to corpus luteum. The development of the follicles is the necessary study of the transverse section of an ovary.
Study of T.S. of Mammalian Testis
The male reproductive organ has two primary structures. A pair of testes and some accessory reproductive structures. Adult mammalian testes perform two essential functions. The first is spermatogenesis, and the second is male sex hormone production. The main male hormone produced in the testis is testosterone. There are a few common diseases linked with the testes such as testicular cancer, testicular trauma, infertility issues, swelling, hypogonadism and more. All these diseases are linked with bruising, clotting and severe pain.
T.S. of Testis Under Microscope
Aim: To study and identify the T.S. Of mammalian ovaries under a microscope through permanent slides.
Apparatus: Permanent slides of T.S. or transverse section of the testis, microscope
Observation: Same as that of the T.S. of the mammalian ovary, the T.S. of mammalian testis also has a thick fibrous tissue covering it known as tunica albuginea. Tubules are present inside the interstitial tissues. The formation of gametes in the T.S. of mammalian testis starts from Spermatogonia to Spermatozoa. This last stage is sperm formation. The majority of the sperms have Sertoli cells embedded in them.
A Few Precautions Must be Taken While Performing the Experiments:
Make sure to wear laboratory gloves.
Use forceps and other instruments while handling the organs.
Make sure the focus of the microscopic lens is adjusted well enough.
Once the experiment is over, store the slides carefully and clean the microscopic lens.
All of the experiments mentioned above are performed by using the transverse section of the testis and transverse section of an ovary of mice and grasshoppers. The anatomy of the two organs remains the same for all mammals.
Solved Examples
Difference Between Testis and Ovary.
The Difference Between Testis and Ovary is Mentioned as Follows:
Functions of Testis and Ovary
Both the testes and the ovaries produce sperms and ova in the males and females respectively. Along with these feet also produce hormones required for reproduction.
Fun Facts About The T.S. of Mammalian Ovary
Ovaries are gray-pinkish in color. A woman’s ovaries are capable of holding millions of eggs at a time.
The size of the ovaries changes along with the maturity of a female body.
During the reproductive phase, the ovaries become more significant in size.
Once a woman reaches menopause, the uterus holds only 400-500 eggs which are not suitable for fertilization anymore.
The eggs are fertilized inside the ovary during the reproductive phase.
FAQs on Identification of Stages of Gamete Development Made Easy
1. What is gametogenesis and why is it studied using transverse sections of the testis and ovary?
Gametogenesis is the biological process by which diploid precursor cells undergo meiosis and differentiation to form mature haploid gametes (sperm and ova). It is studied using a transverse section (T.S.) because this view allows for a clear observation of the structural arrangement and sequential stages of cell development. In a T.S. of the testis, one can see the progression of spermatogenesis within the seminiferous tubules, while in the ovary, the development of follicles at various stages of oogenesis is visible.
2. What are the key identification features in a T.S. of a mammalian testis showing the stages of spermatogenesis?
When observing a transverse section of a mammalian testis under a microscope, the following key features can be identified to understand spermatogenesis:
- Seminiferous Tubules: These are the circular or oval structures where sperm production occurs.
- Germinal Epithelium: The outermost layer of cells in the tubule.
- Spermatogonia: Diploid cells found along the basement membrane of the tubule.
- Primary Spermatocytes: Larger cells, located inwards from spermatogonia, undergoing Meiosis I.
- Secondary Spermatocytes: Smaller, haploid cells that are rarely seen as they quickly enter Meiosis II.
- Spermatids: Small, haploid cells found towards the centre (lumen) of the tubule.
- Spermatozoa (Sperms): Mature gametes with distinct heads and tails, often seen in the lumen.
- Sertoli Cells: Large, supportive cells extending from the basement membrane to the lumen, providing nourishment to developing sperm.
3. How can you identify the different stages of follicular development in a T.S. of a mammalian ovary?
In a transverse section of a mammalian ovary, different stages of oogenesis can be identified by observing the development of the ovarian follicles:
- Primary Follicle: Consists of a primary oocyte surrounded by a single layer of cuboidal follicular (granulosa) cells.
- Secondary Follicle: The oocyte is larger, surrounded by multiple layers of granulosa cells (stratum granulosum). A fluid-filled space, the antrum, begins to appear.
- Graafian Follicle (Tertiary Follicle): A large, mature follicle with a prominent, single, fluid-filled antrum. The oocyte is located within a mound of granulosa cells called the cumulus oophorus.
- Corpus Luteum: A large, yellowish, glandular structure formed from the remnants of the Graafian follicle after ovulation. It may also be visible depending on the stage of the cycle.
4. What is the primary histological difference between observing spermatogenesis in a testis T.S. and oogenesis in an ovary T.S.?
The primary difference is in the arrangement and continuity of the process. In a T.S. of the testis, spermatogenesis is a continuous process, and a single seminiferous tubule shows all stages simultaneously, arranged sequentially from the periphery to the lumen. In contrast, oogenesis is a cyclical process. A T.S. of an ovary shows follicles at various, distinct stages of development scattered throughout the cortex, representing a snapshot in time of the menstrual cycle, rather than a single, continuous line of development.
5. How do Sertoli cells and Leydig cells contribute to spermatogenesis, and how are they identified in a slide?
Sertoli cells, also known as nurse cells, are large cells located inside the seminiferous tubules. They are identified by their large, pale nuclei and their shape, which extends from the basement membrane to the lumen. Their primary function is to nourish and support the developing sperm cells. Leydig cells, or interstitial cells, are found in the connective tissue (interstitial space) between the seminiferous tubules. They are identified as clusters of cells outside the tubules and are responsible for producing and secreting testosterone, the hormone essential for spermatogenesis.
6. What is the main objective of studying gamete development in Class 12 Biology practicals as per the CBSE 2025-26 syllabus?
The main objective is to develop the skill of microscopic observation and identification. Students are expected to study permanent slides of the T.S. of the testis and ovary to understand the histology of these organs. By identifying the different cell types and their arrangements, students can visually correlate the theoretical knowledge of the sequential stages of spermatogenesis and oogenesis with their actual microscopic appearance, reinforcing their understanding of human reproduction.
7. Why do all stages of spermatogenesis appear simultaneously in a seminiferous tubule, while an ovary shows follicles at different, separate stages of maturity?
This difference arises because spermatogenesis is a continuous and asynchronous process that occurs along the length of the seminiferous tubules after puberty. Millions of sperm are constantly being produced, so any given cross-section will show cells at every stage of development. Conversely, oogenesis is a discontinuous and cyclical process, tied to the menstrual cycle. Each month, a group of follicles begins to develop, but usually, only one reaches full maturity (Graafian follicle) and ovulates. Therefore, an ovarian slide presents a 'snapshot' of this cycle, showing follicles at various independent stages of growth or degradation (atresia) scattered in the cortex.
8. What is a Graafian follicle and what is its significance in the process of oogenesis?
A Graafian follicle is the fully mature ovarian follicle that contains the secondary oocyte, ready for ovulation. It is characterised by a large, fluid-filled cavity called the antrum. Its significance is twofold: first, it provides the final environment for the oocyte to complete Meiosis I and mature. Second, its rupture during ovulation releases the oocyte into the fallopian tube, making it available for fertilisation. It is also a primary site of estrogen production in the ovary.
