Fertilisation and week 1 development

what are the pre-natal periods known as?

Embryonic phase and foetal phase

what weeks of development is the embryonic phase?

weeks 0-8

what weeks of development is the foetal phase?

weeks 9-40

what happens in the pre-embryonic period?

fertilisation

cleavage

implantation and bilaminar disc formation

what happens during the embryonic period?

gastrulation

neurulation

organogenesis

morphogenesis

what is teratology?

study of abnormal development

what can cause birth defects?

genetic and chromosomal disorders

environmental factors

complex interactions between genes and environment

what are the 5 types of teratogen?

physical

chemical

nutritional

hormonal

infection

what is a malformation?

a complete or partial absence of a structure or alteration in its normal configuration - can be caused by environmental or genetic factors

what is disruption?

morphological alterations of already formed structures and are caused by destructive processes

what is deformation?

abnormal form due to mechanical factors over a prolonged period

what are some primary development processes?

Cell division

differentiation

cell attachment

apoptosis

induction

cell migration

what are some secondary development processes?

Axis formation/polarity

folding and rotation

increase and decrease in mass or dimension

what is hypertrophy?

increase in cell size

what is hyperplasia?

increase in the number of cells

what happens to oogonia prenatally?

they undergo several mitotic divisions and arrest in prophase of meiosis 1

what are the 3 phases that a follicle goes through?

primary follicle → antral follicle → Graafian follicle

what does the corpus luteum do?

releases hormones (progesterone and some oestrogen) with the purpose of preparing the uterine mucosa for implantation of the embryo

what are the steps of spermatogenesis?

formation of the acrosome

condensation of the nucleus

formation of neck, middle piece and tail

shedding of excess cytoplasm as residual bodies

what happens to sperm at the ischmus?

they become less motile and stop

what happens to sperm during ovulation?

they become hyperactive and highly motile

what role do secretins play?

they cause the removal of the protective protein coat that covers the acrosome of the sperm

what are the 3 phases of fertilisation?

penetration of the corona radiata

penetration of the zona pellucida

fusion of sperm and oocyte membranes

what is the acrosome reaction?

the release of acrosomal enzymes from sperms acrosomal cap to help sperm penetratethe zona pellucida

what happens when the sperm and oocyte fuse?

cortical and zona pellucida reactions

resumption of meiosis II

metabolic activation of the egg

what does the cortical and zona pellucida reaction cause?

the oocyte membrane becomes impenetrable to other sperm, zona pellucida is altered to prevent sperm binding and penetration, prevents polyspermy

what is cleavage?

series of rapid mitotic divisions with no overall increase in size

what is an embryoblast and what will it become?

its the inner/ central blastomere which will become the embryo proper

what is a trophoblast and what will it become?

its the peripheral blastomere which will become the foetal component of the placenta

what is hatching?

when the zona pellucida is shed to allow future interactions with endometrial lining of the uterus