Lecture 1: Introduction/Gametogenesis I Flashcards Preview

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Flashcards in Lecture 1: Introduction/Gametogenesis I Deck (32):
1

Embryology

Study of the embryo, can be descriptive or experimental

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Ontogeny

Includes all developmental processes from conception to death

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Embryogeny

That part of ontogeny from conception to birth/hatching

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Determination

Process by which a cell/part of an embryo becomes restricted to a given developmental pathway

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Differentiation

Complex of changes involved in progressive specialization of structure/function, often resulting in the formation of luxury molecules

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Growth

Permanent increase in mass; hyperplasia or hypertrophy

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Morphogenesis

Generation of form/assumption of new shape

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Induction

An effect of an inductor on a responder such that the developmental course of responder is qualitatively changed from what it would have been in the absence of the inductor

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Integration

Process by which different tissues are brought together and combined to form organs and tissues

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Phase 1: Gametogenesis

Extraembryonic origin of germ cells and migration to gonads

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Phase 2: Gametogenesis

Increase in number of germ cells by mitosis

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Phase 3: Gametogenesis

Reduction in chromosomal number by meiosis

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Phase 4: Gametogenesis

Structural/functional maturation of the eggs and spermatozoa

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Where/when do primordial germ cells first appear following fertilization?

Yolk sac, 24 days after fertilization (humans)

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What is the migration route of the germ cells from the yolk sac to the developing gonads?

yolk sac, hindgut epithelium, dorsal mesentery, developing gonads

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Teratoma

Tumor-like growths from misdirected migrating primordial germ cells containing mixtures of highly differentiated tissues

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Major events in meiosis

Synapsis, crossing over, 2 cell divisions, 1 cycle of DNA replication

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Major results of meiosis

Increase in cell numbers, genetically unique and haploid daughter cells

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Prophase I - Leptotene

Threadlike chromosomes with 2 chromatids begin to coil

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Prophase I - Zygotene

Synapsis occurs, synaptonemal complex forms

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Prophase I - Pachytene

Maimum coiling, tetrads, crossing over begins

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Prophase I - Diplotene

Crossing over continues, chiasmata well defined

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Prophase I - Diakinesis

Crossing over complete, terminalization, spindle apparatus in place, nuclear membrane disrupted

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Metaphase I

Tetrads line up along equatorial plate, centromeres do not divide

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Anaphase I

Homologous chromosomes move to opposite poles, each consisting of 2 genetically unique chromatids

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Telophase I

Cytokinesis occurs, nuclear membranes reform, spindle apparatus disassembles, chromosomes may uncoil

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Prophase II

Chromosomes condense, nuclear membrane disappears, spindle apparatus reforms

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Metaphase II

Chromosomes line up on equatorial plate

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Anaphase II

Centromeres divide, chromosomes move to opposite poles, each chromosome has single chromatid

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Telophase II

Chromosomes uncoil, cytokinesis complete, nuclear membranes reform
END RESULT: 4 genetically unique haploid daughter cells

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Aneuploidy

Abnormal number of chromosomes; ex: monosomy, trisomy

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Euploidy

Changes in the number of complete sets of chromosomes; ex: monoploidy, diploidy, polyploidy