Chapter 16 and 17 course packet part 2 Flashcards
Prenatal period, zygote is
Secondary oocyte, that has only gone through meiosis 1, that is penetrated by a sperm at fertilization
What happens once the zygote, which is the secondary oocyte, is penetrated by a sperm?
The cortical granules in the egg cytoplasm release chemicals that make the zone pellucid impentrable to other sperm
Once the sperm tail degenerates what happens
The oocyte nucleus completes meiosis 2, the sperms haploid nuclues enlarges & fuses with the egg’s haploid nucleus
What is the result once the sperms haploid enlarges and fuses with the egg’s haploid nucleus
The result being a diploid zygote. The individuals karyotype is now established
What happens within 24 hours of the zygote period
The first mitosis or cleavage will commence
What is morula?
The initial cells divide in perpendicular planes.
During the morula stage, by 4 days after fertilization and the 3rd round of cleavage what is there?
16 embryonic cells arranged in a compact ball called a morula
Still contained within the zona pellucid, the morula is physically
The same size as the mature ovum;
What is the stage that usually reaches the uterus from the oviduct?
The morula stage
Different cells (or blastomeres) of the morula have different what
Developmental fates for a particular individual
On day 5 the morula begins to show signs of what
Organization. The ball of cells forms a fluid-filled cavity with the bulk of cells to one side
What is the organization stage of the morula called
Blastocysts, and ONLY the inner cell mass will become the fetus
What stage at 6-7 days implants into the uterine endometrium
The blastocysts stage
What is shed prior to implantation
The zona pellucida
What occurs between 10-14 days
Complete implantation and the early formation of the extra embryonic membranes (amnion, chorion, and yolk sac)
Embryo is what type of stage
The stage which entails all the developlmental steps from 2 weeks after fertilization until the end of the 8th week takes up most of the first trimester
What began in the blastocyst stage really gets going in the
Early embryonic stage: Gastrulation
What does Gastrulation entail?
It entails the cell divisions, migrations, and rearrangements that produce 3 germ layers
What are the 3 germ layers?
1) Endoderm
2) Mesoderm
3) Ectoderm
7 Main points from endoderm
1) Epithelia (internal)
2) GI & respiratory tracts
3) Urinary bladder
4) Urethra
5) parts of inner ear
6) Parts of endocrine glands
7) tonsils & liver
5 Main points for mesoderm (middle layers)
1) Cartiliage & bone
2) Muscle & connective tissue
3) Spleen
4) Adrenal cortex
5) Excretory & reproductive system
6 Main points for the Ectoderm (outermost)
1) Epidermis & its derivatives
2) CNS & PNS
3) Sensory epithelia of eyes, ears & nose
4) Pituitary gland
5) Tooth enamel
6) Adrenal medulla
During the embryonic stage, the 3 germ layers split into what
Subpopulations of cells which become the cellular foundations of future organs
Where do we find organ formation or organogenesis
As diff. sets of cells become unique in structure & function, both in prescribed patterns & at prescribed times
