Gametogenesis Flashcards
Embryology
Study of the embryo, subed into descriptive or experimental
Developmental Biology
What the difference between ontogeny and embryogeny?
Ontogeny is all development from conception to death
Embryogeny is the development from conception to birth or hatching
What are the six component processes of development?
Determination
Differenciation
Growth
Morphogenesis
Induction
Integration
Determination
Process by which a cell or part of an embryo becomes restricted to a given developmental pathway
Differentiation
Compls of changes in progressive specization of structure and function, and the formation of luxury molecules
Not all cells need the same housekeeping molecules or organeeles, or smal number of.
Growth
Permanent increase in mass:
Hyperlasia - increase in cell numbers
Hypertrophy - increase in cell size
Morphogenesis
Generation of form or assumption of new shape
Induction
An effect one embryonic tissue (inductor) has upon another (responder) such that the development course of the respounding tissue is qualitatively changed from. What it would have become before the prescence of the inductor
The notochord in an inductor
Integration
The process of different tissues coming together to combine into organs and other tissues
What are the basic phases of Gametogenesis?
Extraembryonic origin of germ cells and their migration into the gonads
Increase in number of germ cells by mitosis
Reduction in chromosome number by meiosis
Strucural and function maturation of the egges and spermatozoa
Where do the primordial germ cells first appear?
What else is found there?
In the endodermal layer of the yolk sac, appear 24 days after fertilization
Blood vessel form first in the this layer as well.
What is the migration route of germ cells?
Start in layer of yolk sac, to the hindgut epithelium
Through the dorsal mesentery and into the developing gonads
Teratomas
They are growths from misdirected migrating primordial germ cells, which contain mixtures of highly differntiated tissues (all sorts of tissues can be found in them from partial organs to hair, nails or teeth)
What stages of meiosis I do you see crossing over?
Prophase 1, during pacytene, diplotene and diakinesis
Only one chromotid of a pair undergoes crossing over
What do somatoplasm and germ plasm refer too?
Somatoplasm - all somatic cells in a individual
Germplasm - all reproductive cell in an individual
What is nondisjunction?
What does it reult in?
The failure of a chromosome to pull apart in meiosis
-anaphase I
Aneuploidy: Monosomy, trisomy
Other meiotic issues result from what type of processes?
Chromosomal changes
- trranslocations
- deletions
- inversions
- duplications
What is euploidly?
Changes in the number of complete sets of chromosomes
Monoploidy
Diploidy
Polyploidy
Prophase I of Meiosis
Leptotene: threadlike chromosomes, two chromotids, coiling begins
Zygotene: synapsis - homologous chromosomes pair, synaptonemal complex forms
pachytene: maximum coilling, tetrads, crossing-over begins
diplotene: crossing-over continues, well defined chiasmata (cross over points)
Diakinesis: terminlization, spindle apparatus, disruption of nuclear membrane, crossing over is complete
Metaphase I
Tetrad line up at the equatoial plate
Centromeres do not divide
Random alignment?
Anaphase I
Homologous chromosome more to opposite poles
Each consists of two chromotids, not gentically identical because of crossing over
Haploid
Telophase I
Cytokinesis occurs, not always
Nuclear membranes may reform
Spindle apparatus refroms, maybe
Chromosomes uncoil slightly
May be an interphase following this stage
Prophase II
Chromosomes condense
Nuclear membranes disappear
Spindle apparatus reforms
Chromosomes consist of two chromotids
One complete set of chromosome in each daughter cell
Metaphase II
Chromosomes line up at equatorial plate
Anaphase II
Centromeres divide
Chromosomes go to poles
Single chromotids
Telophase II
Chromosomes uncoil
Cytokinesis
Nuclear membranes reform
Give four gentically distinct haploid daughter cells
