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MCB 135E Physiology of Development

MCB 135E Physiology of Development. GSI: Jason Lowry Discussion. General Information. Discussions: Mon 4-5 pm in 106 Moffitt Office Hours: Wed 1:30-2:30 in 434 Barker E-Mail: Jlowry@Berkeley.edu. Introduction. Class Overview Syllabus Discussion Topics Growth and Development

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MCB 135E Physiology of Development

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  1. MCB 135EPhysiology of Development GSI: Jason Lowry Discussion

  2. General Information • Discussions: • Mon 4-5 pm in 106 Moffitt • Office Hours: • Wed 1:30-2:30 in 434 Barker • E-Mail: Jlowry@Berkeley.edu

  3. Introduction • Class Overview • Syllabus • Discussion Topics • Growth and Development • Male and Female Reproductive Systems • Fertilization Process • Implantation

  4. Terminology • Physiology • Study of Function • Development • Functional Changes with Age • Fertilization  Death • Follows a predictable timetable with critical events • Growth • Change in Size • Index used to measure development

  5. Concepts • Divisions of Life-Span (Intro. Table 1) • Pre-Natal • Post-Natal Life • Periods of Development (Intro. Table 2) • Starts with fertilization and proceeds in a continuous and orderly sequence throughout the pre-natal and post-natal periods

  6. Gametogenesis • Terminology • Gamete – Either the Mature Sperm or Ovum • Zygote – Formed by the union of the mature Sperm with mature Ovum • Gametogenesis – Development of Male (Spermatogenesis) and Female (Oogenesis) sex cells

  7. Spermatogenesis • Formation of Spermatozoa (Sperm) • Occurs in seminiferous tubules • Involves two distinct maturational processes • Spermatocytogenesis • 1st Stage of sperm formation • Spermatogonium  Spermatids • Involves mitosis initially and then meiosis • Spermiogenesis • Spermatids  Spermatozoa

  8. Male Reproductive Endocrinology

  9. Oogenesis

  10. Fertilization • Terminology • Fertilization • the formation, maturation, and union of the Ovum and Sperm (Zygote) • Roles of Ovum • Contribute the maternal complement of genes • Reject all sperms but one • Provide food reserve until the embryo begins to feed upon exogenous material • Roles of Sperm • Reach and penetrate the egg • Activate the egg to nuclear and cytoplasmic division necessary to embryonic development • Contribute the paternal complement of genes

  11. Capacitation – Changes that occur between sperm and ovum to allow only one sperm to successfully penetrate the ovum (Increase fertilizing capacity) Cleavage – Mitotic division of the zygote into a morula Morula – Ball of cells that will form blastula that will implant in uterus Terminology

  12. Stages of Fertilization • Penetration • Random contact between sperm and egg • Sperm propel past corona cells and attach to zona pelucida • One sperm-One Egg • Activation • Completion of Meiosis of ovum – forms female pronucleus • Sperm Changes – Sperm travels toward center of egg, head swells, becomes male pronucleus • Rearrangement in egg – biochemical changes necessary prior to nuclear fusion • Nuclear Fusion • Union of two pronuclei • Loss of nuclear envelope, contribution of chromosomes to first mitotic cleavage

  13. Results of Fertilization • Reassociation of male and female sets of chromosomes to full diploid number • Physical basis for inheritance and variation • Determination of sex • Activation of ovum into cleavage

  14. Terminology • Implantation – Process of preparation of the uterine zone for blastocyst embedding and the active penetration of this zone by the blastocyst • Nidation – Latin for nest (alternate name for implantation) • Blastocyst – Approximately 60 cells stage where morula has become fluid filled • Of the cells, about 5 clump together to form inner cell mass (ICM) that projects into blastocele

  15. Uterine Preparation • Estrogen • Involved in proliferation of uterus (hypertrophy) • 3-5 Days post-ovulation E dominates and is thought to play a role in transport of ovum • Progesterone • Increased Vascularization (hypervascularization) • 5-7 days post-ovulation, P increases and counters the effect of E thus relaxing uterine contractions • hCG • Prevents corpus luteum regression • Similar to LH • Maintains E+P during early embryonic development

  16. Implantation Events • Days 1-8 • Fertilized egg begins to divide by cleavage into smaller blastomeres • Blastomere increase follows a double synchronous sequence initially, but later becomes asynchronous • Later stage cleavage forms a ball of cells or morula • Fluid begins accumulating in morula and a conversion occurs to the blastula (blastocyst) • Blastocyst attaches to uterine stroma • Outer layer of cells begin to proliferate and invade stroma of uterus

  17. Implantation Events • Days 8-16 • Blastocyst lodged in uterine stroma • Trophoblast (outer cells) invades uterine stroma and begins to form placenta • Blastocele becomes chorionic cavity • Inner cell mass begins to proliferate and form germ disc and primitive entoderm • Complex sequence of chemical and physical interactions occur between ovum and mother • Only about 50% of fertilized eggs successfully implant

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