Module 3: Stages of Animal Development Flashcards
Stages of Animal Development
- Gametogenesis
- Fertilization
- Cleavage
- Gastrulation
- Organogenesis
- Growth
- Senescence
formation of sex cells or gametes from primordial germ cells (PGCs)
gametogenesis
precursors of gametes, which, following meiosis, develop as haploid sperm and eggs
primordial germ cells (PGCs)
type of cell division that gives rise to haploid gametes
meiosis
stage of meiosis that results to two cells with half the chromosome number of the parent cell
first division (Meiosis I)
stage of meiosis wherein the daughter cells will have the same chromosome number as the parent cells
second division (Meiosis II)
____ haploid cells from meiosis I will become ____ haploid cells after meiosis II
two, four
five substages of prophase I
Leptotene, Zygotene, Pachytene, Diplotene, and Diakinesis
tight pairing of the homologous chromosomes; genes on the chromatids of the homologous chromosomes are aligned with each other
synapsis
(substage) synapsis begins; synaptonemal complex forms at specific locations, spreading to cover the entire length of the chromosomes
zygotene
lattice of proteins between the homologous chromosomes
synaptonemal complex
first source of genetic variation produced by meiosis; exchange of chromosomal segments between non-sister homologous chromatids
crossing over
(substage) crossing over occurs, then synaptonemal complex breaks down and the connection between homologous pairs is also removed
pachytene
found at the end of prophase I; pairs are held together only at the chiasmata; four sister chromatids of each pair of homologous chromosomes are now visible
tetrads
(stage of meiosis) tetrads move to the metaphase plate; homologous pairs orient themselves randomly at the equator
metaphase I
(stage of meiosis) second mechanism that introduces variation
metaphase I
(stage of meiosis) no more DNA
replication will occur; replicated chromosomes (sister
chromatids) are the ones that line up along the metaphase plate
metaphase II
where spermatocytogensis and spermatogenesis occur
wall of the seminiferous tubules
initial stage of spermatogenesis; spermatogonia go through mitosis to form more spermatogonia
spermatocytogenesis
diploid, stem cells
spermatogonia
diploid cells that develop from spermatogonia
primary spermatocytes
(spermatogenesis) primary spermatocytes undergo meiosis I to produce _____
two secondary spermatocytes (n)
(spermatogenesis) secondary spermatocytes go through meiosis II and produce _____
four spermatids (n)
spermatids give rise to mature spermatozoa; go through changes in their form so that they become adapted for fertilization
spermiogenesis
membrane-bound compartment at the tip of the head of the spermatid; Golgi apparatus surrounds the anterior of the spermatid
acrosomal cap / acrosome
organelle that produces and releases lytic enzymes
Golgi apparatus
mitochondria fill the opposite end of the spermatid forming the _____
mid-piece
(phase) formation of acrosome
cap phase
(phase) elongation of microtubules on one of the centrioles of the spermatid
tail phase
(phase) residual cytoplasm and some organelles are removed by phagocytosis
maturation phase
(phase) genetic material is tightly packed, highly condensed, and transcriptionally inactive
DNA packaging
epithelial cells of the seminiferous tubules that nourish the germ cells attached to them; responsible for the phagocytosis of the residual cytoplasm
Sertoli cells
migration of the spermatozoon to the epididymis to become a motile sperm cell
spermiation
Sertoli cells secrete testicular fluid to aid sperm as they travel from the seminiferous tubules to the epididymis via _____
peristaltic contraction
occurs in the outermost layers of the ovaries
oogenesis
germ cell; only divide by mitosis during embryogenesis
oogonium
cell that will enter meiosis; develops from oogonium
primary oocyte
first meiotic arrest
prophase I (diplotene I)
At the time of birth, all future eggs are in the _____ stage
prophase
product of meiosis I; primary oocyte divides unequally, with most of the cellular material and organelles going to one cell
secondary oocyte
product of meiosis I; other cell which will get one set of chromosomes and a small amount of cytoplasm; degenerates
polar body
second meiotic arrest
metaphase II
ovum with little yolk
Microlecithal/Alecithal
ovum with moderate yolk
Mesolecithal
ovum with massive yolk
Macrolecithal
ovum where yolk is evenly distributed throughout the cytoplasm as fat droplets and yolk granules
Isolecithal
ovum with centrally-placed yolk
Centrolecithal
ovum where yolk and cytoplasm tend to accumulate at opposite poles
Telolecithal
__ gamete/s is/are produced per primary spermatocyte
4
__ gamete/s is/are produced per primary oocyte
1
