Early Stages Flashcards
(27 cards)
Ectopic pregnancy
implantation in an inappropriate position
Early embryonic loss
Normal, ranges between 25-50% in domestic species
Late embryonic loss
Mummification
Abortion
Causes including viral, nutritional, toxicosis
Placental insufficiency and failure
poor in-utero foetal growth
abortion
embryonic loss
Stages from fertilisation to implantation
2-cell stage -> 4 cell stage -> 8 cell stage -> 16 cell stage -> morula -> blastula
Cleavage
series of rapid mitotic division following fertilisation - asynchronous
Blastomeres
cells resulting from cleavage process - occurs within isthmus
Morula
solid ball of cells consisting of 16-64 blastomeres
Blastocyst is caught on…
a sticky ECM
Central implantation
blastocyst remains within uterine lumen
Eccentric implantation
blastocyst lies within uterine crypt or recess
Interstitial implantation
conceptus invades the uterine wall
Yolk sac
first membrane formed, involved in early haematopoiesis and angiogenesis
Amnion
surrounds foetus, fluid filled, filtration
Amniotic fluid
cushions the foetus, allows movement, ruptures at birth
Amnion at birth in horse, dog and cat
May be born in amniotic sac
Amnion at birth in ruminants and pigs
born without sac
Components of maternal placenta
Endometrial lining of uterus
Components of foetal placenta
Chorion and yolk sac (transitory), chorion and allantois (definitive)
Haemotropic source of nutrients
Maternal blood stream
Histotropic source of nutrients
coiled endometrial glands produce histotrophe (uterine milk)
Diffuse placenta
placental zone covers almost entire surface of chorionic sac
Cotyledonary placenta
Cotyledons develop in response to chorionic contact - caruncles
Zonary placenta
placental zone in band around central region - complete or incomplete
