510-2 Flashcards
What is the difference between an embryo and a fetus?
AGE. An embryo lasts 8 weeks, the fetus is the rest of the trip.
Where is the normal fertilization site in the uterus?
The ampulla region
What is the 1st barrier of the unfertilized ovum?
The corona radiata
What is the second layer of the unfertilized ovum?
The Zona Pellucida “PEL-EW-SID-AH”
Approx how many spermatozoa are deposited into the repro tract? How many SURVIVE reach the oocyte?
~200-300 MILLION deposited, only the strongest three to five hundred make it to the egg.
What is the vesicle of enzymes at the tip of a spermatozoan?
The acrosome
What are the two “reactions” necessary for the sperm to enter the egg?
1st: Acrosome Reaction-enzymes released from the acrosome allow the sperm to get in 2nd: the Zona reaction-The zona pellucida undergoes a rapid, CALCIUM mediated change and another sperm is prevented from entering.
How long does it take for the zygote to develop into the morula? Where does it travel to and from during this time?
It takes 4 days to develop into the morula. It travels from the ampulla to the uterine tube to the uterus.
What is the term for a solid ball of blastomeres?
A morula. Think MULBERRY (and birds pooping)
NAME the 4 cell types yielded by the ECTODERM
“Attract-o-derm” 1)Epidermis 2)ENAMEL 3)Mouth Lining 4)Nervous system
Name the 7 yields of the ENDODERM
1)LIVER 2)Pancreas 3)Thyroid 4) Parathyroid 5)Lining of the Gut 6)Lungs 7)Bladder
Name the 9 yields of the MESODERM
1) Muscles 2)Bones 3)Blood Cells 4)Spleen 5)lymphatic tissues 6)heart 7)lungs 8)reproductive system 9) excretory system
What is undifferentiated connective tissue called?
Mesenchyme
What does gastrulation begin with?
The primitive streak on the epiblast.
After implantation of the blastocyst and rooting of the trophoblast, what does the trophoblast divide into?
1) the Syncytiotrophoblast “SIN-SE-shio-Tropho-blast” 2)Cytotrophoblast
What are the three layers of the Uterus?
1)Perimetrium 2)Myometrium 3)Endometrium
How long does it take from fertilization to two cell stage?
30 hours
How long does it take from fertilization to implantation?
6 days
What does the trophoblast develop into?
The placenta–Troph==Nourish
What is the vascular connective tissue of the uterus?
The endometria Stroma
Cytotrophoblast: Inner or outer? What type of cells?Large?Small?Singular?Plural?
The cytotrophoblast is the INNER layer of the trophoblast and it is mainly LARGE and SINGLE cells.
What is the outer layer of the trophoblast that grows around maternal blood vesicles in the endometrial stroma?
The syncytiotrophoblast
What 2 parts do the epiblast develop into?
The ectoderm and the amniotic cavity
What does the hypoblast develop into?
The yolk sac
What cavity causes the formation of the secondary yolk sac from the primary yolk sac?
The chorionic “CORE-EE-ON-IC” cavity
What hormone does the chorionic tissue produce?
hCG-human Chorionic Gonadotropin-keeps the corpus luteum alive to produce progesterone to maintain the uterus :)
What is at the leading edge of the primitive streak?
The primitive NODE
What does the buccopharyngeal membrane on the epiblast yield?
THE ORAL CAVITY!!
What types of genes do the cells of the primitive STREAK express?
Growth Factors! Bone Morphogenic Protein 4 & Transforming Growth Factor Beta
What types of genes do the cells of the primitive NODE express?
Inhibitory proteins! Block excessive growth of the messderm.
What genes do the cells of the primitive node trigger?
Chordin-notochord Noggin-somites
What portion of the embryo did Hans Spemann experiment with? What was the takeaway?
Spemann played around with the PRIMITIVE NODE, and found that it ORGANIZED the growth of a second head. (Therefore primitive node = head dev.)
What is the role of the GOOSECOID transcription factor?
Goosecoid activates CHORDIN which directs development of the cranial mesoderm. Creates a two headed baby.
What structure do the cells of the primitive node form?
The notochord
What type of effect does the notochord have on surrounding tissues? What type of tissues develop from this effect?
INDUCTIVE effect: causes the development of NERVE MUCSLE AND CONNECTIVE tissue(only epithelial missing,eh?)
What are the only remnants of the notochord in a developed human?
The center of the intervertebral disks. STARTS the axial skeleton (SOMITES!)
What does the buccopharyngeal membrane correspond to? Which end of the notochord? Cranial or Caudal?
The buccopharyngeal membrane corresponds to the mouth and it is Cranial. NO MESODERM
What does the CLOACAL membrane correspond to?Cranial or Caudal end?
CLOW-ACHE-AL membrane corresponds to the anus and it is on the caudal end of the notochord. NO MESODERM
What begins the process of neurulation?
The formation of the Neuroectoderm. This makes up the neural Plate (does not touch, inside of neural tube)
What forms out of the neural tube? Where does the first enclosure begin?
THE CNS. Folds in the middle of the embryo and then proceeds cranially and caudally
WHEN does NEURULATION take place?
Approx 3 weeks
What derm layer forms Somites?
Mesoderm
What develops from somites?
Dermis, muscle, tendons, bones. SKELETAL/Structure
What causes Anencephaly & spina bifida? How can a pregnant woman avoid spina bifida?
“AN-IN-Seph-AL-EE” and spina bifida are caused by incomplete closing of the nural tube. Spina bifida can be avoided with consumption of FOLIC ACID. Green leafy veggies.
What are the two MAIN derivatives of Surface Ectoderm
Mouth epithelium & subsequently Tooth enamel (Repeat right? :)
What are the two main derivatives of the Neural crest?
Facial Cartilage & Dentin<–(ODONTOOBLASTS!)
A clinical example of abnormal neural crest cell migration?
Treacher Collins syndrome
What is an agent such as a drug, virus, or radiation that can cause malformations to an embryo or fetus? When is development most susceptible to malformations?
Teratogen “TER-AT-O-GEN”. 3-8 week embryonic stage.
