Gametogenesis to Implantation Flashcards
prenatal developmental stages
germinal (0-2 weeks), embryonic (3-8 weeks), fetal (9 weeks-birth)
postnatal developmental stages
neonate, infancy, childhood, puberty, adulthood
teratology
birth defects and genetic and environmental factors that cause them
critical period of pregnancy
until 8th week, when placenta forms
germ cells
precursor cells to gametes
when and how are primordial germ cells formed
during 4-6 week
migrate from wall of yolk sac to the developing gonad
sacrococcygeal teratoma
common tumor in newborns
from primordial germ cells (Pluripotent)
contains anatomic structures
totipotent cells
can become entire embryo
pluripotent cells
can develop into any type of cell in the adult body, can’t develop embryonic cells (Trophoblast cells)
multipotent cells
can produce a few types of cells, bone and cartilage
unipotent cells
can give rise to only one cell type
gametogenesis
formation of the gametes
diploid cell matures into a haploid gamete by undergoing meiosis
oogenesis
polar body is extruded
one mature oocyte is formed
follicular cells are released
zona pellucida surrounds ovum
spermatogenesis
no polar body
produces 4 haploid sperm
sertoli cells: differentiates from spermatogonia to spermatid
spermiogenesis: differentiates spermatid to mature sperms
anomalies in gametogenesis
down’s syndrome
edwards
patau
… non disjunction
steps in fertilization
- capacitation of sperm: chemical changes in sperm
- zona penetration: sperm binds to receptor in zona pellucida
- fusion of cell membranes of oocyte sperm
- fusion changes zona pellucida making it impermeable to other sperms to prevent polyspermy
cleavage
zygote initiates rapid series of mitotic cell divisions
daughter cells are called
blastomeres
morula
16 cell stage
