Embryology_flipped_student

Questions/Logistics

• Overview of questions that will be discussed.

• Important logistics related to the exam.

Free Recall

• Practice recalling information without prompts.

• Focus on retaining key concepts and details from previous material.

Mitosis and Meiosis in Spermatogenesis

Figure 46.12a: Male Reproductive System

• Key Components:

  • Epididymis: Stores sperm.

  • Seminiferous tubule: Site of sperm production.

  • Sertoli cells: Support and nourish sperm development, contain nucleus.

  • Lumen of seminiferous tubule: Where sperm matures.

  • Cellular Structures: Plasma membrane, tail, neck, midpiece, head, mitochondria, nucleus, acrosome.

• Cell Types and Stages:

  • Primordial germ cell (in embryo) → Spermatogonial stem cell → Spermatogonium

    • Undergo mitotic divisions.

  • Primary spermatocyte → undergoes Meiosis I, producing Secondary spermatocyte.

  • Spermatids (n) → further differentiation to form mature sperm cells.

  • Stages: Mitosis (2n) → Meiosis I (2n) → Meiotic division II → Sperm cell formation (n).

Mitosis and Meiosis in Oogenesis

Figure 46.12b: Female Reproductive System

• Key Components:

  • Ovary: Site of egg production.

  • Primordial germ cell → Oogonium

    • Undergo mitotic divisions.

  • Primary oocyte: Present at birth, arrested in prophase of Meiosis I.

  • Secondary oocyte: Arrested at metaphase of Meiosis II after ovulation.

  • Polar bodies: Form during oocyte development.

  • Staging: Completion of meiosis I to secondary oocyte, ovulation, fertilization.

Fertilization

Page 5 Overview

• Secondary oocyte in metaphase II; sperm entry sequence.

• Process:

  • Sperm penetrates corona radiata and undergoes acrosome reaction.

  • Fusion of sperm and oocyte membranes and pronuclei.

  • Stages outlined: Phase 1 (penetration), Phase 2 (reaction), Phase 3 (fusion).

Stem Cell Potency

Page 6: Totipotent, Pluripotent, and Multipotent

• Stem Cell Stages:

  • 8-cell stage → Morula.

  • Definitions of stem cell types:

    • Totipotent: Can differentiate into any cell type, including extra-embryonic.

    • Pluripotent: Can become nearly all any cell type but cannot form a full organism.

    • Multipotent: Limited to a particular lineage (e.g., hematopoietic stem cells).

Embryonic Development

Page 7: Blastocyst Formation

• Elements of a blastocyst:

  • Embryoblast: Inner cell mass that develops into the embryo.

  • Trophoblast: Contributes to placenta formation.

  • Cavities: Developing blastocyst cavity, zona pellucida degenerates.

Differentiation and Implantation

Page 8 Overview

• Trophoblast structure:

  • Syncytiotrophoblast vs Cytotrophoblast: Forms during implantation.

• Key areas:

  • Formation of the amniotic cavity, epiblast, hypoblast.

  • Early yolk sac development (Day 9).

Embryonic Development: Bilaminar to Trilaminar Disc

Page 9 Overview

• Transition from bilateral to trilaminar structure.

• Key structures:

  • Trophoblastic villi, Maternal sinusoid: Important for nutrient exchange.

  • Other developmental structures during days 14-16: primitive streak and mesoderm formation.

Types of Twins

Page 10: Fraternal Twins (Dizygotic)

• Result from two separate eggs fertilized by different sperm.

• Genetically unique individuals.

Page 11: Maternal or Identical Twins (Monozygotic)

• Result from a single fertilized egg splitting into two embryos.

• Genetically identical individuals.

Page 12: Placental Differences

• Fraternal Twins: Separate placentas.

• Identical Twins: Can share placenta or have separate inner sacs.

Questions/Logistics: Overview of exam questions and important logistics.

Free Recall: Practice recalling key concepts and details from past material.

Mitosis and Meiosis in Spermatogenesis:

• Key Components: Epididymis (sperm storage), seminiferous tubule (sperm production), Sertoli cells (supporting cells), cellular structures (tail, midpiece, head).

• Stages: Primordial germ cell → Spermatogonial stem cell → Spermatogonium → Primary spermatocyte (Meiosis I) → Secondary spermatocyte → Spermatids → Mature sperm cells.

Mitosis and Meiosis in Oogenesis:

• Key Components: Ovary (egg production), Primordial germ cell → Oogonium → Primary oocyte (arrested in Meiosis I) → Secondary oocyte (arrested in Meiosis II).

• Staging: Oogenesis includes completion of meiosis I, ovulation, and fertilization.

Fertilization:

• Process: Secondary oocyte in metaphase II; sperm penetrates, fuses with oocyte membranes and pronuclei in three phases (penetration, reaction, fusion).

Stem Cell Potency:

• Types: Totipotent (any cell type), Pluripotent (nearly all cell types), Multipotent (limited to a lineage).

Embryonic Development:

• Blastocyst Formation: Includes embryoblast (embryo) and trophoblast (placenta).

• Differentiation and Implantation: Syncytiotrophoblast and cytotrophoblast components; early yolk sac development.

Types of Twins:

• Fraternal Twins (Dizygotic): Two genetically unique eggs fertilized.

• Identical Twins (Monozygotic): Single fertilized egg splitting into two genetically identical embryos.

• Placental Differences: Fraternal (separate placentas) vs. Identical (can share placenta).