my

spermatozoon enters the cytoplasm of the egg

meiosis 2 starts

hypothalamus

produces gonadotropin releasing hormone

stimulates anterior pituitary gland

produces luteinising hormone

estrogen increase

brakes down conectiive tissue around graafian follicle

aids release of oocyte

oocyte has undergone meiosis 1

called secondary oocyte in metaphase 2

sperm ejaculated

vagina - cervix of the uterus - fallopian tubes

zygote

mitotic division

2-4-8-16 cells

morula

contains blastomere cells

forms ovum and second polar body

fluid penetrates zona pellucida

male pronucleus consolidates inside the cytoplasm and it begins to associate with the female pronucleus.

diploid complement of chromosomes

blastocyst

creates blastocyst cavity

(blastocele)

inner cell mass

outer cell mass

specialises into embryoblast

specialises into trophoblast

cytotrophoblast

syncytiotrophoblast

bilaminar disk

amniotic cavity is formed among the epiblast cells

will eventually cover embryo and fetus

connects to the maternal blood vessels

placenta forms

produces B-HCG

goes to the corpus luteum of ovary

continues to produce progesterone

prevents the cells inside the endometrial lining to become necrotic and shed

top layer - epiblast

bottom layer - hypoblast

line the blastocyst cavity and form the primary (primitive) yolk sac

the cells surrounding the yolk sac form a layer called extraembryonic mesoderm

separates embryo from placenta

develops fluid-filled gaps, extraembryonic coelom

when enlarges and wraps around the embryo and yolk sac becomes chorionic cavity

divides primary yolk sac into 2 parts

the part in contact with embryo -(secondary) definitive yolk sac

the part that moves away - exocoelomic cysts

connecting stalk connects embryo to the placenta

becomes umbilical cord

bilaminar disc becomes polorised by migration of epiblast cells from later aspect towards the midline

on one side epiblast cells collapse inwards to create a primitive streak

(at the caudal end)

tip of the primitive streak - primitive pit

cells inside the primitive pit - primitive node

prochordal plate

cranial end