Zoo lab 2 Flashcards
Unfertilized sea star egg
Germinal vesicle (nucleus)
Nucleolus (darkly stained within the nucleus)
Fertilized egg
Fertilization membrane
Identify the name of the cleaved cells,
why doesn’t the structure change size between embryonic cell cleavage?
Blastomeres
They don’t change size because the blastomeres are cleaved radially in this instance. It does not duplicate itself to create an equally sized cell to the original, rather it splits to create two equal halves of an original cell.
Identify the structure and stage of development
Blastula
Blastocoel is within the blastula
How can you identify late and early stages of a blastula?
Size only.
What stage of development is this and label it
Early Gastrula
Blastocoel
Archenteron
Endoderm
Ectoderm
Blastopore
What stage of development is this and label it (ignore 2)
Late Gastrula
Ectoderm
Blastocoel
Coelomic sac
Mesoderm
Endoderm
Archenteron
Blastopore
What stage of development and what is going on?
Bipinnaria larva
mouth, esophagus, stomach, intestine, anus
Coelomic sacs expand and the mesodermal cells proliferate to form the skeletal, muscular, and peritoneal structures of the body.
The mouth forms from the ectoderm contacting the stomodeum (2nd), making this a deuterostome.
The blastopore becomes the anus.
Shortly after formation of the mouth, the archenteron differentiates to form the gut (esophagus, stomach, intestine, and anus).
Frog eggs are … whereas seastar eggs are …
Mesolecithal ; Isolecithal
Stage of development in a frog egg?
Blastula
Blastocoel
Stage of development in a frog egg?
Late Gastrula
Archenteron (closest to ectoderm)
Endoderm
Ectoderm
Blastocoel
Yolk plug
Stage of development?
Early Gastrula
Archenteron
Blastocoel
Stage of development in a frog egg?
2 cell stage composed of 2 blastomeres
Differences between sea star and frog egg?
Yolk quantity is greater in frog eggs because they are mesolecithal and seastar eggs are isolecithal, meaning the frog eggs have concentrated yolk at the vegetal pole whereas the seastar has little yolk evenly distributed. This greater amount of yolk impedes cleavage and causes structures to be located near the animal pole of a frog blastula and gastrula as a consequence of cleavage being impeded by yolk. The seastar egg has no issue developing its structures evenly throughout the animal-vegetal axis because yolk does not impede its cleavages.
Morphological differences of tadpole and frog
gut changes, head widens and eyes go further to the sides, loses tail, grows 4 appendages, larger mouth
