Flashcards in Lect 1: Gametogenesis I Deck (33):
Study of the embryo. Descriptive and experimental (developmental bio).
Includes all developmental processes from conception to death
That part of ontogeny from conceptions to birth/hatching
Process by which a cell or part of an embryo becomes restricted to a given developmental pathway.
Complex of changes involved in progressive specialization of structure and function, often resulting in the formation of luxury molecules
Permanent increase in mass. Hyperplasia (increase in cell numbers) Hypertrophy (increase in cell size)
Generation of form or assumption of new shape.
An affect one embryonic tissue (inductor) has upon another (responder) such that the development course of the responding tissue is qualitatively changed from what it would have been in the absence of the inductor
Process by which different tissues are brought together and combined to form organs and tissues
Phases of Gametogenesis
*Extraembryonic origin of germ cells and their migration into the gonads
*Increase in # of germ cells by mitosis
*Reduction in chromosomal # by meiosis
*Structural and functional maturation of the eggs and spermatozoa
Following fertilization, when do the primordial germ cells first appear?
24 days after fertilization
What is the migration route of the primordial germ cells?
Yolk sac -> hindgut epithelium, through dorsal mesentery, into developing gonads.
Growths from misdirected migrating primordial germ cells. Contain mixtures of highly differentiated tissues.
Process of gametogenesis in females and products
Oogenesis - eggs
Process of gametogenesis in males and products
Spermatogenesis - spermatozoa
Stages of Meiosis
Prophase I, Metaphase I, Anaphase I, Telophase I Prophase II, Metaphase II, Anaphase II, Telophase II
Substages in Prophase I
Leptotene, Zygotene, Pachytene, Diplotene, Diakinesis
Prophase I - Leptotene
Chromosomes are threadlike. Each chromosome consists of 2 chromatids. Chromosomes begin to coil
Prophase I - Zygotene
Homologous chromosomes pair (synapsis). Synaptonemal complex forms.
Prophase I - Pachytene
Maximum coiling. Tetrads. Crossing-over begins
Prophase I - Diplotene
Crossing over continues. Chiasmata are well defined.
Prophase I - Diakinesis
Crossing-over is complete. Terminalization. Spindle apparatus is in place. Nuclear membrane is disrupted.
Tetrads line up along equatorial plate. Centromeres do not divide.
Homologous chromosomes move to opposite poles. Each homologue consists of 2 chromatids. Chromatids are not genetically identical b/c of crossing-over. Daughter cells will be haploid.
Cytokinesis occurs (usually). Nuclear membranes reform (maybe). Spindle apparatus disassembles. Chromosomes may uncoil to varying degrees.
Chromosomes again condense. Nuclear membranes disappear. Spindle apparatus reforms in each cell. Each chromosome consists of 2 chromatids. Each daughter cell has 1 complete set of chromosomes (haploid)
Chromosomes line up on equatorial plate
Centromeres divide. Chromosomes move to opposite poles. Each chromosome consists of a single chromatid.
Chromosomes uncoil. Cytokinesis is complete. Nuclear membranes reform. End result is 4 genetically unique haploid daughter cells.
Abnormal number of chromosomes. Monosomy/Trisomy
Changes in number of complete sets of chromosomes. Monoploidy/Diploidy
Meiosis requires how many divisions and replication?
2 consecutive cell divisions but only 1 cycle of DNA replication