Embryology
EMBRYOLOGY
DEVELOPMENT * Sequential expression of the genes * Organisms proceeds from cell fertilized egg to adulthood to eventual death
Successful development * Has to follow the prescribe sequence in normal pattern
Three Fundamental Processes in Embryology: 1. Morphogenesis * (morph- = shape, + genesis = origin) * Origin of shape, form
2. Differentiation * Process of cells becoming different, and specializing for different functions 3. Growth * Increase in size, requires input of matter, food
Two Modes of Reproduction * SEXUAL * ASEXUAL (METAGENESIS)
Indirect development * Exhibited by the eggs of most marine invertebrates and those of many freshwater vertebrates * feeding larval forms that look and behave differently from mature adult * Eggs often contain rather limited food reserves and programmed for rapid differentiation
Direct development * Exhibited by eggs of mammals, birds and reptiles * Develops without passing through a highly specialized larval phase *
Oviparity and Viviparity
Oviparous - Animals that spawn (lay their eggs) * Viviparous – animals that give birth * Ovoviviparity - which embryos develop inside eggs that are retained within the mother's body until they are ready to hatch * Euviparity – designates the viviparous condition
Gametogenesis * Converts diploid (2N) into haploid cells (N), sperm or ova * Originated from stem cell which grow into primary oocyte and primary spermatocyte * Undergo meiosis
Stages of Development * Fertilization * Cleavage * Blastulation * Gastrulation * Neurulation * Organogenesis
STAGES OF ANIMAL DEVELOPMENT
FERTILIZATION
* Sperm release enzymes that pierce the egg’s coat. * Receptor protein of eggs – surface protein of sperm, plasma membrane fuse and nuclei combine * Change in polarization – only 1 sperm enters * Fertilization restores the 46
DEVELOPMENT * Sequential expression of the genes * Organisms proceeds from cell fertilized egg to adulthood to eventual death
Successful development * Has to follow the prescribe sequence in normal pattern
Three Fundamental Processes in Embryology: 1. Morphogenesis * (morph- = shape, + genesis = origin) * Origin of shape, form
2. Differentiation * Process of cells becoming different, and specializing for different functions 3. Growth * Increase in size, requires input of matter, food
Two Modes of Reproduction * SEXUAL * ASEXUAL (METAGENESIS)
Indirect development * Exhibited by the eggs of most marine invertebrates and those of many freshwater vertebrates * feeding larval forms that look and behave differently from mature adult * Eggs often contain rather limited food reserves and programmed for rapid differentiation
Direct development * Exhibited by eggs of mammals, birds and reptiles * Develops without passing through a highly specialized larval phase *
Oviparity and Viviparity
Oviparous - Animals that spawn (lay their eggs) * Viviparous – animals that give birth * Ovoviviparity - which embryos develop inside eggs that are retained within the mother's body until they are ready to hatch * Euviparity – designates the viviparous condition
Gametogenesis * Converts diploid (2N) into haploid cells (N), sperm or ova * Originated from stem cell which grow into primary oocyte and primary spermatocyte * Undergo meiosis
Stages of Development * Fertilization * Cleavage * Blastulation * Gastrulation * Neurulation * Organogenesis
STAGES OF ANIMAL DEVELOPMENT
FERTILIZATION
* Sperm release enzymes that pierce the egg’s coat. * Receptor protein of eggs – surface protein of sperm, plasma membrane fuse and nuclei combine * Change in polarization – only 1 sperm enters * Fertilization restores the 46