Embryogenesis and Development Flashcards
What sex are embryos by default?
female <3
Fertilization usually occurs in the…?
ampulla
Acrosomal apparatus
the first sperm to come in contact with the secondary oocyte’s cell membrane, forms a tubelike structure
Cortical reaction?
after the sperm penetrates the cell membrane, a release of calcium ions occurs; the calcium ions depolarize the membrane of the ovum, prevents fertilization of the ovum by multiple sperm cells and increased calcium concentration increases the metabolic rate of the newly formed zygote
Cleavage (for cells)
as the zygote moves to the uterus for implantation, the zygote undergoes rapid mitotic cell divisions in a process called cleavage!
indeterminate and determinate cleavage
indeterminate cleavage
cells that can still develop into complete organisms
determinate cleavage
results in cells with fates that are already determined; committed to differentiating into a certain type of cell
morula
embryo becomes a solid mass of cells
blastula
when morula undergoes blastulation, in which the blastula, a hollow ball of cells with a fluid-filled inner cavity known as a blastocoel; mammal’s are called blastocyst
chorionic villi
microscopic fingerlike projections that penetrate the endometrium
yolk sac
what the embryo is supported by until the placenta is fully functional
allantois
involved in early fluid exchange between the embryo and the yolk sac, ultimately, the umbilical cord is formed from remnants of the yolk sac and the allantois, allantois is surrounded by the amnion, a thin, tough membrane filled with amniotic fluid
gastrulation
generation of three distinct cell layers
archenteron
membrane invagination into the blastocoel, later develops into the gut, opening of this is called the blastopore, turns into the anus (in deuterostomes), like humans, in protostomes, it turns into the mouth
ectoderm
outermost layer, gives rise to the integument, including the epidermis, hair, nails, and the epithelia of the nose, mouth, and lower anal canal, the lens of the eye, nervous system (including adrenal medulla), and inner ear are also derived from ectoderm
mesoderm
develops into several systems including the musculoskeletal, circulatory, and most of the excretory systems, gives rise to gonads as well as the muscular and connective tissue layers of the digestive and respiratory systems and the adrenal cortex
endoderm
epithelial linings of the digestive and respiratory tracts, including the lungs, pancreas, thyroid, bladder, and distal urinary tracts, as well as parts of the liver, are derived from endoderm
selective transcription
only the genes that are needed for a particular cell are transcribed
induction
ability of one group of cells to influence the fate of nearby cells
inducers
diffuse from organizing cells to the responsive cells, chemicals are responsible for processes such as the guidance of neuronal axons
neurulation
development of the nervous system, can occur once the three germ layers are formed
teratogens
substances that interfere with development ex. alcohol or high blood glucose
specification
cell is reversibly designated as a specific cell type
determination
the commitment of a cell to a particular function in the future
morphogens
molecules that can cause a neighboring cell to follow a particular developmental pathway
differentiation
changing the structure, function, and biochemistry of the cell to match the cell type
totipotent
cells that can differentiate into any cell type, either fetal of placental
pluripotent
cells that can differentiate into any cell type in the fetus
multipotent
cells that can differentiate into multiple cell types within a particular group
autocrine signals
act on the same cell that secreted the signal in the first place
paracrine signals
act on cells in the local area
juxtacrine signals
do not usually involve diffusion, but involve a cell directly stimulating receptors of an adjacent cell
endocrine signals
involve secreted hormones that travel through the bloodstream to a distant target tissue
Growth factors
often inducers, peptides that promote differentiation and mitosis in certain tissues
apoptosis
programmed cell death
necrosis
process of cell death in which a cell dies as a result of injury
senescence
biological aging
What happens as a cell divides ?
It’s telomeres/end of chromosomes will shorten
umbilical arteries
carry blood away from the fetus, carry deoxygenated blood
umbilical veins
carry blood towards the fetus from the placenta, carries oxygenated blood
Does a fetus depend on its own lungs and liver?
No, it has shunts to direct blood away from them while they develop
Foramen ovale
one-way valve that connect the right atrium to the left atrium , allows blood that enters the right atrium from the inferior vena cava to flow into the left atrium instead of the left atrium instead of the right ventricle and thereby be pumped through the aorta
Ductus arteriosus?
Shunts leftover blood in the pulmonary artery to the aorta
Ductus venosus?
liver is bypassed by this shunt, blood returning from the placenta via the umbilical vein directly into the inferior vena cava, liver still receives some blood supply from smaller hepatic arteries in the systemic circulation
Parturition
vaginal childbirth, accomplished by rhythmic contractions of the uterine smooth muscle, coordinated by prostaglandins and the peptide hormone oxytocin
- water breaks
- birth of child
- expulsion of placenta and umbilical cord (afterbirth)
