the union of a single egg and sperm, marks the beginning of pregnancy.
diploid number is restored
egg and sperm formation
release of egg
union of the gametes
body cells replicate to yield two cells with the same genetic makup as the parent cell. First the cell makes a copy of DNA and then it divides; eacg daughter cell recieve one copy of the genetic material.
the process ny which germ cells divide and decrease their chromosomal number by half, produces gametes
the process of egg(ovum) formation, begins during fetal life in the female.
the united egg and sperm
when a male reaches puberty-testes then under go spematogenis
the cells that undrgo meiosis in the male
when the sperm successfully penatrates the membrane surrounding the ovum, both sperm and ovum are enclosed within the membrane and the membrane become impenetrable(zona reaction).
Mitotic cellular replication (cleavage) begins as the zygote travels the length of the uterine tube into the uterus
a solid ball of cells, is produced within 3 days and still surrounded by the protective zona pellucida
give rise to the embryo
when the cavity becomes recognizable, the whole structure its the developing embryo
btwn 6-10 days after conception, the trophoblast secretes enzymes that enable it to burrow into the endometrium until the entire blastocyst is covered.
placenta is form
vascular process that obtain o2 and nutrients from the maternal bloodstreem and dispose of Co2 and waste products into the maternal blood.
the portion directly under the blastocyst, where the chorionic villa tap into the maternal blood vessels.
give rise to the epidermis, the glans , the nails, hair, CNS, PNS
dvlps into teeth, muscles(skeletal, smoothm cardiac), connective tissue
give rise to the digestive and respiratory tract, bladder
organ systems and the main external features. succeptible to malformation. lasts from day 15- 8 weeks of conception
cover fetal side of the placenta. contains major umbilical blood vessels
inner cell membrane
amniotic fluid functions
1. constant body temp
2. source of oral fluid and repositor for waste and assists in maintenance of fluid and electrolyte homeostasis
3. freedom of movement and musculoskeletal dvlp
4. cushions fetus
having less then 300ml of amniotic fluid. its associated withe renal abnormality
having 2l of amniotic fluid. its associsted with gi malformastiom
function of yolk sac
aids in transferring maternal nutrients and oxygen, which have diffused through the chorion to the embryo.
connective tissue, which prevents compression of the blood vessels and ensures continued nourishment of the embyro/fetus
cord is wrapped around the fetal neck
peripheral location is less common in reference to the umbilical cord
human chorionic gonadotropin
detcted 8-10 after conception
hcg percerves the function of ovaian corpus luteum which ensure the continued supply of estrogen and progesterone(needed to maintaine the preg.)
human chorionic somatomammotropin
stimulates the maternal metabolism to supply nutrients needed for fetal growth.
Increases the resistance to insulin, faciliates glucose transport across the placental membran and stimulate breast dvlp to prepare for lactation.
protects the skin of the fetus
very fine hair.
only immunioglobin that crosses the placenta
immunoglobin that passes in the breast milk, providing passive immunity.
2 mature ovums are produced in one ovarian cycle, both have the potential to be fertilized by seperate sperm.
Fraternal twins-can be the same sex of different sec and are genetically no more alike then siblling borm at different times.
one fertilized ovum which then divides. They are the same sex and have the genotype
incomplete embryonic division at 13-15 days
environmental substances or exposures that result in function or structural disablility.
drugs, chemicals, infections, exposure to radiation, and certain maternal conditions diabetes and PKU