3.1 Early developmental stages Flashcards
What is the difference between determinante and indeterminate cleavage.
Indeterminate cleavage: results in cells that can still develop into complete organisms.
Determinate cleavage: the cells are already determined to be a specific type of cell, i.e. differentiate into a specific type of cell.
What does the ectoderm turn into?
Gives rise to the ectoderm.
Integument: epidermis, hair, nails, epithelia of nose, mouth, and lower anal canal.
lens of eye
nervous system & the inner ear
adrenal medulla
Ecto=attratoderm= cosmetic features (skin) and ‘smarts’ (brain)
What does the mesoderm turn into?
Musculoskeletal system
Circulatory System (i.e. heart)
Excretory system
Gonads
Muscular and connective tissue layers of the digestive and respiratory system, and adrenal cortex.
“means” oderm: the means of getting around an organism, such as bones, and muscle, the means of getting around the body such as the circulatory system, and means of getting around, like the gonads
What does the endoderm turn into?
Epithelia lining of digestive and respiratory tracts, including the lungs.
Also pancreas, thyroid, bladder, and distal urinary tracts, as well as parts of liver
Endoderm: linings of the ‘endernal’ (internal) or internal organs, such as the digestive and respiratory tract, and accessory organs attached to these systems.
What does the neural crest develop into?
Neural crest cells become the peripheral nervous system (including the sensory ganglia, autonomic ganglia, adrenal medulla, and Schwann Cells) as well as specific cell types in other tissues (such as calcitonin-producing cells of the thyroid.
How does induction influence development?
Induction is the process by which nearby cells influence the differentiation of adjacent cells. This ensures proper spatial location and orientation of cells that share a function or have complimentary functions.
What are the stages of embryonic development up to the gastrula?
Zygote–> 2, 4, 8, and 16-cell embryo –> morula –> blastula (blastocyst) –> gastrula.
Where does fertilization with the sperm to the egg occur?
In the fallopian tube.
More specifically, in the ampulla which is the widest part of the fallopian tube
What is the acrosomal apparatus?
This happens when sperm head (acrosome) gets in contact the the secondary oocyte’s cell membrane and forms a tube like structure called the acrosomal apparatus.
The pronucleus of the sperm can then go into the oocyte once meiosis II has come to completion.
What is the cortical reaction?
What is the impenetrable membrane that is formed after fertilization called?
This occurs when the sperm penetrants the cell membrane.
This causes a release of calcium ions, which then depolarize the membrane of the ovum to: prevent fertilization of the ovum by multiple sperm cells, and the increased calcium which increases the metabolic rate of the newly formed diploid zygote.
What’s the difference between dizygotic (fraternal) twins and monozygotic (maternal) twins.
Fraternal/Dizygotic Twins: two different eggs, two different, non-identical twins.
Paternal Monozygotic Twins: happens when a single zygote separates into two. Genetic material is identical.
What is the process of cleavage?
This is the rapid mitotic cell division of the zygote.
The first cleavage creates an embryo, no longer is it a zygote.
The cells divide into progressively smaller cells that have the following function: increase nuclear to cytoplasmic ratio and surface area to volume ration. Why? Because there is more area for gas and nutrient exchange relative to overall volume.
What is blastulation?
What is Morula, blastula, blastocoel, trophoblast cells, and inner cell mass?
Morula: solid mass of cells
Blastulation: the process by which the morula forms the blastula.
Blastula: a hollow ball of cells whih a fluid filled inner cavity known as a blastocoel or blastocyst.
The blastocyst contains two cell groups: trophoblast cells & inner cell mass
Mnemonic: a blastula is an embryo with a blasted-out cavity.
In the Blastula, what do the trophoblast cells do?
They create an interface between the maternal blood supply and the develop into the chorion, which then develops into the placenta.
They also form the chorionic villi, which are microscopic finger-like projections that penetrate the endometrium, and help support maternal fetal gas exchange.
The umbilical cord connects the placenta to the vascular system of the embryo.
What is the yolk sac?
It is the site of early blood cell development and helps support the embryo until the placenta forms.
What is the allantois?
This is involved in early fluid exchange between the embryo and the yok sac.
The umbilical cord is formed from the remnants of the yolk sac and the allantois.
What is the amnion?
This is a thin, tough membrane filled with amniotic fluid.
It helps protect the embryo from trauma too.
What is gastrulation?
This is the generation of three distinct cell layers that occurs after the cell mass implants.
The three cell layers are the: ectoderm, mesoderm, and endoderm.
From zygote to gastrula, what are the various stages of development?
Zygote–> 2, 4, 8, and 16-cell embryo –> morula –> blastula (blastocyst) –> gastrula.
What is the notochord, neural folds, neural grove, neural tube, and neural crest cells?
The notochord induces a group of overlying ectodermal cells to form neural folds surrounding the neural grove.
The neural folds fuse to form the neural tube, which becomes the central nervous system
The tip of the neural fold contains the neural crest cells, which become the peripheral nervous system.
