Embryo 2 Flashcards
List all stages of fertilisation
Capacitation
Acrosome reaction
Adhesion of sperm
Penetration of zona pellucida
Fusion of cell membranes
End of second maturation division
Formation of pronuclei
Karyogamy
List the gestational period of animals
Cattle -9 months
Horse- 11 months
Swine - 3 months, 3 weeks, 3 days
Sheep/goat 5 months
Dog - 63 days
Cat- 62 days
What do PGCs form
Depending on sex PGCs become spermatogonia or oogonia
Characterise the germinal layer that arises from the wall of the yolk sac
Primordial germ cells
migrate form the yolk sac to the indifferent gonadal analage. During their migration, they multiply by mitotic division. colonise the gonadal analge. Depending on the sex, PGCs become spermatogonia or oogonia
How does the indifferent gonadal anlage differenciation decide which sex an organism is
If a Y chromosome is present, a testis develops from the undifferent anlage.
If a X chromosome is present, a set of ovaris is formed from the undifferent anlage
Name 3 types of spermatogonia
Type A = stem cells
intermediate
Type B
Explain briefly the stages how spermatids are transformed into spermatozoa
Golgi phase - head, neck and tail are formed
Cap phase - the acrosomal granule flattens and covers a large portion of the spermatid nucleus
Acrosomal phase- cytoplasm allocated development of tail
Maturation phase - species specific architecture of the sperm head and tail is developed. spermatids disconnect from each other and spermatozoa are released form sertoli cells into lumen of seminiferous tubules
Characterise the parts of spermatozoon
Head:
Nucleus-tightly packed chromatin
Acrosome- covers the anterior portion of the nucleus
Plasma membrane
Equatorial region
Postacrosomal region
Neck:
connected to head by basal plate
Contains: proximal and distal centrioles
Tail:
middle piece, principal piece, end piece
Describe the middle piece of tail of spermatozoon
middle piece contains a flagellum, contains:
a central axonema with 2 microtubule and 9 peripheral doublets
9 course (outer dense) fibres
A helix of elongated mitochondria
Only difference is principal has no mitochondria
List all germ layers in logial sequence
Ectoderm, mesoderm, endoderm
Draw a Blastocyst
Zona pellucida
Inner call mass
Trophoblast
Blastocyst cavity
Previtelin space
List all fetal membranes in order
Yolk sac
Amnion
Allantois
Chorion
Characterise the umbilical cord
The connecting stalk between the foetus and the placenta, consists of :
foetal mucoid CT
Two umbilical arteries
Two umbilical veins
The urachus
Vestige of the yolk sac
Characterise the umbilical cord
The connecting stalk between the foetus and the placenta, consists of :
foetal mucoid CT
Two umbiliva arteries
Two umbilical vein
How are dizygotic twins created
Two oocytes are ovulated, both are fertilised giving two embryos, two zygotes which develop separately so each of them has its own fetal membrane
