Flashcards
Dev biology
Flashcards do conjunto (16)
- 1OviparityAnimals from eggs (birds, frogs, most invertebrates)
- 2ViviparityLive birth (placental mammals)
- 3ovoviviparityan egg that hatches inside the body (n certain reptiles and sharks)
- 4Holoblastic cleavageEntire egg is divided into successively smaller cells, as it is in frogs and mammals
- 5Meroblastic cleavageas in chicks, wherein only part of the egg is destined to become the embryo while the other portion—the yolk—serves as nutrition for the embryo
- 6BlastomeresCells in the cleavage-stage
- 7Control of blastomeres' division rate and placement in most species (except mammals) is achieved byproteins and mRNAs stored in the oocyte.
- 8fast cleavage in invertabrates to restore the somatic ratio of nuclear volume to cytoplasmic volume is due toabolishing the gap periods of the cell cycle (the G1 and G2 phases), when growth can occur
- 9pattern of cleavage is determined by1. Amount and distribution of yolk protein (inhibits cleavage)
2. Factors in the egg cytoplasm that influence the angle of the mitotic spindle and the timing of its formation - 10vegetal poleThe yolk-rich pole
- 11animal polelow yolk concentration
- 12isolecithal(Greek, “equal yolk”) -> eggs of sea urchins, mammals, and snails
- 13Source of nutrition for isolecithal eggs1. Larval form
2. Maternal placenta - 14MesolecithalModerate vegetal yolk disposition
- 15TelolecithalDense yolk throughout most of cell
- 16CentrolecithalYolk in center of egg
Informações
- Descrição
- Cleavage and gastrulation
- Criado por
- Alexandra Shabanova
- Visualizações
- 1
- Avaliação