ANAT 1607 Embryology Chapters 3-6

ANAT 1607 Embryology Chapters 3-6 - CH. 3 - 1st week of...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
CH. 3 - 1 st week of Development These will probably be most useful when looking at the diagrams in the book. Fertilization Ampulla - usual site of fertilization - longest and widest part of the uterine tube - * if not fertilized, oocyte moves to uterus, degenerates, and is resorbed - carbohydrate and protein-binding molecules on gamete surfaces are involved in sperm chemotaxis and gamete recognition, and process of fertilization. Phases of Fertilization -Sperm passes through the corona radiate of the oocyte -Acrosome of sperm releases hyaluronidase, which disperses the follicular cells of the corona radiate and allows the sperm to penetrate. -Penetration of Zona Pellucida -Acrosome enzymes: esterases, acrosin , and neuraminidase create pathway through zona pellucida to the oocyte. - Sperm enters zona pellucida zona reaction other sperm can’t enter -Sperm and Ooctye membranes fuse -head and tail of sperm enter but plasma membrane remains behind. -2nd meiotic division of oocyte, and female pronucleus formation. -mature oocyte and 2 nd polar body form -decondensation of maternal chromosomes -mature oocyte pronucleus -Formation of male pronucleus -sperm nucleus enlarges pronucleus -tail degenerates - (male and female pronuclei replicate DNA during growth) - Pronuclear membranes breakdown -Chromosomes condense -Chromosomes arrange for mitotic division -Fertilization is complete within 24 hours of ovulation . -Early Pregnancy Factor (EPF) – is secreted by trophoblastic cells and appears in maternal serum in 24 to 48 hours after fertilization. Results of Fertilization - Secondary oocyte completes 2 nd mitotic division 2 nd polar body - Diploid # of chromosomes restored (46) - Mingling of moms and dads chromosomes variation of species - Determines embryo sex: X=female and Y=male - Zygote is unique b/c half its chromosomes come from mom and half come from dad. Cleavage of the Zygote – repeated mitotic division of zygote - rapid increase in number of cells ( blastomeres) # 2,4,8,16, etc - blastomeres become smaller w/ each cleavage - occurs while zygote goes from uterine tube uterus
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
- Compaction - blastomeres change shape and align into a tight ball o Prerequisite for segregation of internal cells that form embryoblast (inner cell mass) of blastocyst - Morula 12-15 blastomeres - Trophoblast (outer cell mass) – layer of flattened cells that surround embyroblast ( inner cell mass) Formation of Blastocyst - Fluid from uterine cavity zona pellucida blastocystic cavity (in morula) fluid increases blastomeres separate into 2 parts: - 2 parts: o Trophoblast- thin outer cell embryonic part of placenta o Embryoblast- centrally located blastomeres embryo - Now called blastocyst - Embryoblast projects into blastocystic cavity - Trophoblast forms blastocyst wall - All takes place within zona pellucida - Blastocyst sheds zona pellucida after 2 days in uterine fluid - allows rapid growth of blastocyst - (~6 days) Blastocyst attaches to endometrium epithelial
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 8

ANAT 1607 Embryology Chapters 3-6 - CH. 3 - 1st week of...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online