Embryology Lecture - Gametogenesis of Reptiles.pptx

Discover the fascinating world of reptilian reproduction in our upcoming presentation, "Gametogenesis of Reptiles." Dive into the complex processes of sperm and egg formation, explore the unique adaptations of different reptile species, and learn about the environmental factors influencing these processes. This presentation will cover:

Overview of gametogenesis in reptiles.
Detailed stages of spermatogenesis and oogenesis.
Hormonal regulation and species-specific differences.
Comparisons with other vertebrates.
Environmental impacts on gametogenesis.
Case studies from various reptile groups.
Latest research and technological advancements.
Perfect for students, researchers, and enthusiasts, this session promises to deepen your understanding of reptilian biology and the importance of conserving their habitats. Join us and gain valuable insights into the resilience and adaptability of these incredible creatures!

1. GAMETOGENESIS OF REPTILES Rodriguez, Tolentino, Viñas

2. topic description GAMETOGENESIS OF REPTILES Gametogenesis in reptiles refers to the process by which primordial germ cells (PGCs) develop into gametes, specifically spermatozoa in males and ova in females. 2

3. topic outline 01 Topic What is gametogenesis 02 Topic Spermatogenesis in Males 03 Topic Oogenesis in Females 04 Topic Impact of Environmental Factors on Gametogenesis 05 Topic Comparative Aspects 06 Topic Recent Research and Findings

4. 01 What is gametogenesis topic

5. topic 1 What is gametogenesis Gametogenesis is the biological process by which diploid or haploid precursor cells undergo cell division and differentiation to form mature haploid gametes. This process is crucial for sexual reproduction and the continuation of species. GAMETOGENESIS OF REPTILES 5 Types of Gametogenesis Spermatogenesis: The development and maturation of sperm cells in males. Oogenesis: The development and maturation of egg cells in females.

6. 02 Spermatogenesis in Males topic

7. topic 2 Spermatogenesis in Males GAMETOGENESIS OF REPTILES 7 Reptilian spermatogenesis refers to the biological process by which primordial germ cells (PGCs) develop into mature spermatozoa in male reptiles. This process involves several stages: Stages of Spermatogenesis Migration of PGCs : PGCs migrate from the yolk sac to the gonads during embryonic development. Mitosis and Differentiation : PGCs undergo mitosis and differentiate into diploid gametogonia, which then differentiate into primary gametocytes. Meiosis I and II : Primary gametocytes undergo meiosis I and II, resulting in haploid secondary gametocytes and then gametids . Spermiogenesis : Gametids undergo spermiogenesis, a process of morphological changes, resulting in the formation of spermatozoa.

8. Spermatogenesis in Males GAMETOGENESIS OF REPTILES 8

9. Spermatogenesis in Males GAMETOGENESIS OF REPTILES 9

10. GAMETOGENESIS OF REPTILES 10 Reptile spermatozoon

11. 03 Oogenesis in Females topic

12. topic 3 Oogenesis in Females GAMETOGENESIS OF REPTILES 12 Reptile oogenesis refers to the biological process by which female gametes (ova/eggs) are formed in reptiles. Stages of Oogenesis Migration of PGCs : Primordial germ cells (PGCs) migrate from the yolk sac to the gonads during embryonic development. Mitosis and Differentiation : PGCs undergo mitosis and differentiate into diploid gametogonia, which then differentiate into primary oocytes. Meiosis I and II : Primary oocytes undergo meiosis I and II, resulting in haploid ova. Folliculogenesis : Ova mature within ovarian follicles through several stages, including follicular cell proliferation, thecal cell differentiation, and antrum enlargement.

13. Oogenesis in Females GAMETOGENESIS OF REPTILES 13

14. 04 Impact of Environmental Factors on Gametogenesis topic

15. topic 4 Impact of Environmental Factors on Gametogenesis Temperature Temperature plays a crucial role : Temperature is the single most important environmental factor influencing gametogenesis in reptiles. It affects the hormonal status and physiology of reptiles, which in turn impacts gametogenesis and steroidogenesis. Seasonal changes : Many reptiles exhibit seasonal changes in reproductive activity, with some species showing a period of sexual rest after the breeding period. Environmental factors like temperature and humidity can synchronize these cycles Environmental Stressors Pollution : Environmental pollutants can affect gametogenesis by altering the molecular and structural content of gametes. This can have evolutionary consequences for the fitness of offspring. Climate change : Climate change can impact gametogenesis by altering the pre-release and post-release gamete environments. This can affect fertilization outcomes and offspring traits GAMETOGENESIS OF REPTILES 14

16. 05 Comparative Aspects topic

17. topic 5 Similarities Gonad Morphology: The adult gonad morphology is remarkably similar across different vertebrate species, including reptiles. Both testis and ovary exhibit a similar conservation in their organization, with the testis featuring testis cord structures and the ovary having a cortical-medullary structure. Germ Cell Development: The process of germ cell development, including the origin of primordial germ cells (PGCs), their migration to the gonads, and the subsequent mitotic and meiotic divisions, is conserved across vertebrates. This includes the formation of haploid gametes through meiosis and the final stages of maturation and differentiation into spermatozoa and ova. GAMETOGENESIS OF REPTILES 17 Comparative Aspects

18. topic 5 Differences Reproductive Cycles: Reptiles exhibit well-defined annual reproductive cycles and breeding seasons, which is different from some other vertebrates like amphibians and fish. Many reptilian species are oviparous, but some exhibit viviparity, which is relatively rare in other vertebrates. Hormonal Regulation: Reptiles have separate FSHs and LHs, unlike some other vertebrates. Squamate reptiles, for example, rely on a single FSH-like hormone, whereas crocodilians and turtles produce two distinct gonadotropins GAMETOGENESIS OF REPTILES 18 Comparative Aspects

19. topic 5 Differences Sperm Development: Spermatogenesis in reptiles is characterized by the presence of spermatothecae , which allow females to store sperm for extended periods. This is different from some other vertebrates where sperm are released immediately after mating. Model Organisms: Reptiles, particularly semi-aquatic species, can serve as sentinel species for studying the effects of aquatic pollutants on germ cell development. Their testis morphology is more similar to that of other amniotes, including humans, making them a useful model for histopathological studies. GAMETOGENESIS OF REPTILES 19 Comparative Aspects

20. Comparative Anatomy GAMETOGENESIS OF REPTILES 20

21. 06 Recent Research and Findings topic

22. GAMETOGENESIS OF REPTILES Spermatogenesis in reptiles follows a similar pattern to other vertebrates, involving the differentiation of spermatogonial stem cells into spermatozoa through a series of mitotic and meiotic divisions. Studies have provided insights into the hormonal regulation and molecular mechanisms controlling this process in various reptile species. Oogenesis in reptiles also shares commonalities with other vertebrates, with the development of primary oocytes from oogonial stem cells and their subsequent growth and maturation. Researchers have investigated factors influencing follicular development and ovulation in reptiles. 22 Recent Research and Findings

23. GAMETOGENESIS OF REPTILES Temperature-dependent sex determination, a unique feature of many reptiles, has been an area of intense study. Researchers have identified key genes and signaling pathways involved in the temperature-sensitive process of gonadal differentiation. Advances in reproductive biotechnologies, such as in vitro fertilization and cryopreservation of reptile gametes, have enabled new possibilities for conservation efforts and assisted reproductive techniques in endangered reptile species. Overall, the study of reptile gametogenesis continues to yield valuable insights into the evolution and diversity of reproductive strategies across vertebrates, with implications for both basic science and applied conservation efforts. 23 Recent Research and Findings

24. lesson summary Reptiles exhibit a simpler and more straightforward series of germ cell morphologies compared to other amniotes, making them a suitable model for studying sperm development and the effects of toxins on germ cell development. Reptilian testes have a histological arrangement of germ cell generations like that of mammals, but unlike birds and mammals, reptiles lack a consistent spatial germ cell development. Reptiles are semi-aquatic and relatively abundant, making them potential sentinel species for studying the impact of aquatic pesticides on germ cell development In summary, reptilian gametogenesis is highly sensitive to environmental factors, making them important models for understanding the evolutionary consequences of environmental change on reproduction and development. Ongoing research continues to elucidate the complex genetic and physiological pathways underlying reptilian sex determination and gametogenesis GAMETOGENESIS OF REPTILES 24

25. THANK YOU FOR LISTENING GAMETOGENESIS OF REPTILES 25

26. Presented by: RODRIGUEZ, Ralph TOLENTINO, Sam Tyrone Viñas , Johann Rafael GAMETOGENESIS OF REPTILES 26

27. Author links open overlay panelWilfrid Dubois, & AbstractThis work is a study of testicular function in Chrysemys picta using changes in ultrastructure and steroid histochemistry as indices of Leydig and Sertoli cell activity. The cytological features of these cells are described in reference to four pe. (2004, December 6). The annual testicular cycle in the Turtle, Chrysemys picta : A histochemical and electron microscopic study . General and Comparative Endocrinology. https://www.sciencedirect.com/science/article/pii/0016648088902481 Encyclopædia Britannica, inc. (2024a, June 12). Encyclopædia Britannica. https://www.britannica.com/animal/reptile/Courtship-and-fertilization Encyclopædia Britannica, inc. (2024b, June 12). Encyclopædia Britannica. https://www.britannica.com/animal/reptile/Embryonic-development-and-parental-care Ferreira, A., & Dolder , H. (n.d.). Sperm ultrastructure and spermatogenesis in the Lizard, Tropidurus Itambere . Biocell . http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S0327-95452003000300006 Gametogenesis . Gametogenesis - an overview | ScienceDirect Topics. (n.d.). https://www.sciencedirect.com/topics/medicine-and-dentistry/gametogenesis Genome integrity and instability: “Meiotic chromosome dynamics and double strand break formation in reptiles.” IBB UAB. (1970, October 21). https://ibb.uab.cat/index.php/2022/10/12/genome-integrity-and-instability-meiotic-chromosome-dynamics-and-double-strand-break-formation-in-reptiles/ In vitro gametogenesis. (n.d.-a). https://digitalcommons.liberty.edu/cgi/viewcontent.cgi?article=2379&context=honors Kohno, S., Parrott, B. B., Yatsu , R., Miyagawa, S., Moore, B. C., Iguchi, T., & Guillette Jr., L. (2014, March 13). Gonadal differentiation in reptiles exhibiting environmental sex determination . Karger Publishers. https://karger.com/sxd/article-abstract/8/5/208/304470/Gonadal-Differentiation-in-Reptiles-Exhibiting?redirectedFrom=fulltext Luo, Y., & Yu, Y. (2021, December 27). Research advances in gametogenesis and embryogenesis using pluripotent stem cells . Frontiers. https://www.frontiersin.org/articles/10.3389/fcell.2021.801468/full PMC, E. (n.d.). Europe PMC. https://europepmc.org/article/med/22319673 Showing variations in sperm structure across different ... (n.d.-b). https://www.researchgate.net/figure/Showing-variations-in-sperm-structure-across-different-vertebrates-a-b-Toad-Fish_fig1_326827104 Sphenodon . Sphenodon - an overview | ScienceDirect Topics. (n.d.). https://www.sciencedirect.com/topics/immunology-and-microbiology/sphenodon Squamate . Squamate - an overview | ScienceDirect Topics. (n.d.). https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/squamate Yoshimatsu, S., Kisu, I., Qian, E., & Noce, T. (2022, June 29). A new horizon in reproductive research with pluripotent stem cells: Successful in vitro gametogenesis in rodents, its application to large animals, and future in vitro reconstitution of reproductive organs such as “ uteroid ” and “ oviductoid .” MDPI. https://www.mdpi.com/2079-7737/11/7/987 GAMETOGENESIS OF REPTILES 27