Flashcards in Intro to Embryo 8-24 Deck (39)
Fertilization to 8 weeks - initial development of all major structures and establishment of all organ systems
9th week (57 day) to 38th week - differentiation and growth of organs and tissues
Study of abnormal development (generic/environmental causes)
last normal menstrual period - 40 week pregnancy as opposed to 38 week pregnancy from fertilization to birth
Formation of PMGs, occurs at week 7
Primordial Germ cells - originate from endodermal cells of umbilical vesicle near origin of allantois as specific cells lining yolk sac. Migrate to gonads where they mature. Start as large cells recognizable 24 days after fertilization.
Where germ cells migrate
Will form ovaries or testies
Cannot differentiate between sexes
Occurs in month 3 - at prophase I it halts. Only about 500 are ovulated. Oogonia to oocyte - 2 million oocytes.
Like a funnel focused @ ovary.
Little fingers over ovary from infundibulum. Smooth muscle then moves egg through ampula (fertilization likely occurs here).
Spermatogonia to sperm
Maximum number of oocytes
Month 5 - 7 million oocytes
All oocytes in meiosis I, birth, 600-800K oocytes
First occurrence of menstruation, 400K oocytes
Immotile all are 23X, Corona radiata, Zona pellucida
FSH, LH (anterior pituitary) - prior to fertilization
follicular stimulating hormone. Tells 10-15 of the oocytes to start meiosis II and I.
Leutinizing hormone - surge that causes oocyte to be spit out to be picked up by fimbriae
causes only 1 sperm to be able to break into the nucleus
12-32 blastomeres. Important stage because of inner and outer cell mass.
Occurs after ejaculation 7hrs. Surface proteins remove acrosome, allows acrosome to interact with corona radiata and ZP.
Type of sperm motility, helps sperm penetrate ZP
Allows sperm to break ZP.
Zona reaction, sperm and oocyte cell membranes break down and fuse. Oocyte completes meiosis and forms pronucleus. Haploid pronuclei fuse and form diploid zygote --- initiates cleavage. 1. Coronal cells 2. Acrosomal reaction 3. Fusion
Early embryonic cells from zygote that start to form within 30 hours of fertilization. Zona pellucida confines cells.
Begins at 8 cells
Implantation occurs in abnormal position - usually in uterine tubes.
Embryo in abdomen, calcifies
Results in heavy bleeding.
no more zona pellucida. Fluid enters blastocystic cavity and separates blastomeres. Trophoblast and Embryoblast
Forms extra embryonic structures (placenta). Troph=nutrients.
Best place for implantation. Tropoblast cells attach to endometrium. Once this occurs, tropoblast differentiates into cytotrophoblast and syncytiotrophoblast (day 7).
Line blastocystic cavity
"Finger" type cells that extend and attach to endometrium.