Across
- 4. an embryo is an egg that has been fertilised by a sperm and undergone at least one _________.
- 9. (2 words) in order for implantation to occur successfully, the embryo must develop within the ____ ______ (glycoprotein membrane), blastocyst must hatch, maternal recognition and extra-embreyonic membranes must form.
- 10. refers to the formation of the 3 germ layers (endo, meso, ecto)
- 11. in mammals, the _________ stage follows the embryonic stage
- 12. within the morula, blastomeres begin to differentiate into outer cells (which will form trophoblast) and inner cells (which will form inner cell mass). The inner cells have GAP junctions to increase communication – will form embryo and foetal membranes. The outer cells have ______ junctions to reduce permeability to fluids (will eventually form chorion and amnion)
- 13. the period of the ovum lasts from fertilisation to the end of the first week. Includes transport of zygote to uterus, mitosis, and transformation from zygote __________ blastocyst.
- 14. gene expression depends on genetic history (commitment) and current cellular ________ (intercellular communication)
- 17. the inner most cell layer formed by gastrulation is the endoderm, which goes on the form mucosal epithelium and glands of the respiratory and ____________ tracts.
- 18. time of hatching of the blastocyst varies between species, with humans and pigs taking a shorter time, and dogs and cats a ________ time.
- 19. the structure in fgure 1, labelled b, is the _________ ______ ______, forms the ‘animal pole’
- 22. the rupture (or degeneration in rodents and horses) of the zona pellucida and the release of the blastocyst is known as _________ and is accompanied by a marked increase in size.
- 23. pig gestation lasts for 114 days and includes 3 broad periods of gestation - ____, embryo, foetus.
- 24. structure A shown in figure 1 is a ____________. It is the early stage in development BEFORE implantation.
- 26. the ectoderm (outer) eventually differentiates to form skin, oral and nasal epithelium, and the ________ system.
- 27. the inner cell mass of a blastocyst contains many ____ junctions between cells.
- 29. cleavage produces smaller cells called ____________. No increase in cell size, just cell number.
- 31. with cleavage, there is no icrease in cell ____, in fact there is a decrease.
Down
- 1. cleavage results in a ______ ball of cells known as the morula.
- 2. the process of tissues interacting and becoming permanently changed.
- 3. process of cells becoming different from one another.
- 5. the ordered assembly of cells to form complex organs.
- 6. the secretions of the blastomeres within the morula form a ___________ (labelled d in fig 1). The embryo is then known as the blastocyst.
- 7. haploid reproductive cell (sperm or egg)used to pass chromosomes to offspring
- 8. the first diploid cell formed by fusion of egg and sperm
- 15. during cleavage, the first _____ blastomeres are undifferentiated. After this, the blastomeres begin to differentiate into inner and outer cells.
- 16. the outer cell layer of a blastocyst, labelled c in figure1.
- 20. refers to the mitotic division of the zygote. Occurs within zona pellucida (mammals). Produces smaller cells called blastomeres
- 21. cells can decide to divide, differentiate, interact with one another, move from place to place, change morphology, or undergo ___________ (eg finger webbing cells)
- 25. the pattern of cleavage (partial or total) depends on size of the ____. Eg avian have large volume of ____, partial cleavage. Mammals have small ____, total cleavage.
- 28. increase in size, cell number, cell size and cell products.
- 30. the mesoderm forms connective tissues, bone, components of circulatory/urinary/genital systems, as well as _______.