Spermatogenesis ___ by Ashish Verma 1.pptx

Spermatogenesis, Sperm Production Process, Structure of Sperm. Gametogenesis

1. Topic – Spermatogenesis Submitted By – Ashish Verma M.Sc. IV Semester Department of Zoology Paper – Gamete Biology, Development and Differentiation Government Autonomous Post Graduate College Chhindwara (M.P.) 480221

2. Content Introduction Definition Type A and Type B Cells Spermatogenesis Process a) Formation of Spermatids b) Spermateleosis Structure of Sperm Spermatogenesis in rodents Conclusion References

3. Introduction Spermatogenesis describes the production of spermatozoa (sperm) in the seminiferous tubules of the testes • The process begins at puberty Sperm are produced in the seminiferous tubules of the testes and become mature in the epididymis. The entire process takes about 9 to 10 weeks.

4. Fig. Cross Section of Seminiferous tubule

5. The process of producing mature sperm is called spermatogenesis Definition

6. Type A and Type B Cells In spermatogenesis, there are two main types of cells involved: type A and type B cells. 1. Type A cells : These are the stem cells or spermatogonia that are undifferentiated and capable of self-renewal. 2. Type B cells: They are committed to spermatogenesis and undergo meiosis to eventually form sperm cells (spermatozoa).

7. Spermatogenesis is completed in two steps. a) Formation of Spermatids :- Primordial germ cells (PGCs) → Spermatids ( Spermatid genesis) Spermatids form in following steps 1) Multiplication phase – PGCs divide through mitotic division. - The daughter cells formed by the PGCs are called Spermatogonia. 2) Growth phase – Store food material, Size increase, Primary Spermatocytes formed 3) Maturation phase :- i) First Maturation Division – Primary Spermatocytes  Second spermatocytes ii) Second Maturation Division – Spermatids Formed (Four haploid spermatids form by a single primary spermatid) Spermatogenesis Process

8. Fig. Process of Spermatogenesis

9. b) Spermateleosis / Spermiogenesis In this phase, each sessile and round spermatid converts into mobile and thread like sperm. The process is divided into following parts :- Changes in Nucleus – Nucleus of spermatid reduces to form the head of sperm Formation of acrosome – In anterior part of sperm in front of nucleus. (Filled with enzymes – hyaluronidase and proteases) Centriole :- Both the centriole of spermatids are arranged one after the other, behind the nucleus. Mitochondria :- This mitochondria gradually fuse together and take the form of a contracted body on either side of axial filament.

10. Fig. Stages of Metamorphosis of the Spermatid into the Spermatozoon

11. Structure of Sperm Fig. A)Mature Sperm B) Electron Microscopic View of Fully Mature Sperm

12. In the mouse, the entire development process from stem cell to spermatozoon takes 34.5 days. ( 5 weeks) The spermatogonial stages last 8 days, meiosis lasts 13 days, and spermiogenesis takes up another 13.5 days . Morphological basis in rodents

13. Conclusion Spermatogenesis is a vital process in male reproductive biology, responsible for the continuous production of sperm cells. It involves a series of precisely regulated steps, including mitotic divisions, meiotic divisions, and morphological transformations, ultimately resulting in the formation of mature spermatozoa. Spermatogenesis is influenced by hormonal, environmental, and genetic factors, and disruptions in this process can lead to male infertility. Understanding the mechanisms and regulation of spermatogenesis is crucial for addressing reproductive health issues and developing strategies for fertility preservation and treatment .

14. References Developmental Biology - by Scott. F. Gilbert Life Sciences – Fundamental and Practice – by Usha mina and pranav Kumar

15. Thank You !