5.12 Structure of the egg, development of embryo and hatching of larva Flashcards
What is the length and width of a honeybee egg?
A honeybee egg is around 1.5 mm long and about 0.33 mm wide.
What is the weight of a honeybee egg?
The weight of a honeybee egg is 0.13 mg.
Describe the shape of a honeybee egg.
The egg is slightly curved, with the head or anterior end wider than the posterior end. The dorsal side is convex and the ventral side is concave.
What is the chorion?
The chorion is an outer layer that forms a continuous protective layer around the egg cell.
What is the micropyle?
The micropyle is a hole found in the anterior part of the chorion, where the trophocytes were attached, serving as the passageway for sperm to enter the egg for fertilization.
What is the vitelline membrane?
The vitelline membrane surrounds the liquid called cytoplasm beneath the chorion.
What does the nucleus of the egg cell contain?
The nucleus contains the DNA or genetic material of the egg cell.
What happens to the egg once it is laid?
Once laid, the egg begins to change to form the embryo, regardless of whether it is fertilized or not.
What is cleavage in the context of embryo development?
Cleavage is the process where the fertilized egg divides by mitosis, producing identical cells called cleavage cells.
What is a blastoderm?
The blastoderm is a layer of cells formed by the migration of cleavage cells.
What forms the germ band?
An area of the blastoderm on the ventral side thickens and produces more cells, forming the germ band.
What structures do the lateral plates form?
The lateral plates form the ectoderm, which develops into structures such as the trachea, nervous system, and external parts of the bee.
What structures do the median plates form?
The median plates form the mesoderm, which develops into muscles, heart, and inner reproductive organs.
What does the endoderm form?
The endoderm forms from the remaining blastoderm and migrates inwards to create the digestive system.
What is the significance of invaginations in embryo development?
Invaginations or folds from both ends fuse to form the digestive tract.
How does the body plan of the honeybee compare to higher animals?
The honeybee’s 3-layered body plan is the same as that of all higher animals, including humans.
What surrounds the developing larva within the egg?
The developing larva is enclosed within the chorion and surrounded by the amnion.
What happens towards the end of the egg period?
The embryo develops recognizable features and segments, becoming similar to a larva.
What occurs after 72 hours of development?
After 72 hours, the larva begins to wriggle, the chorion splits, and the egg hatches into a new larva.
What process forms an increasing number of nuclei surrounded by cytoplasm?
The process is known as syncytial cleavage.
What are the cleavage cells surrounded by cytoplasm called?
They are known as energids.
How are the initial mitotic divisions of energids characterized?
They are synchronized across all energids.
What forms a continuous cell layer after cleavage cells migrate towards the vitelline membrane?
The continuous cell layer is known as the blastoderm.
How do mitotic divisions change as the blastoderm develops?
The divisions are no longer synchronized, taking longer in different parts of the blastoderm.
What thickens on the ventral side of the blastoderm?
The thickening becomes the germ band.
What structures are formed from the germ band?
The germ band divides into a median plate and a pair of lateral plates
What does the median plate become?
The median plate moves into the yolk and becomes the mesoderm.
What do the anterior and posterior rudiments form?
They form the endoderm (in time these invaginations will form the fore and hind gut.).
What systems and structures develop from the ectoderm?
The nervous system, tracheal system, legs, wings, mouthparts, and sting.
How does the nervous system develop from the ectoderm?
It comes from thickenings running the length of the ectoderm.
What does the mesoderm develop into?
It develops into the internal structures of the honeybee, including the heart, aorta, diaphragms, and reproductive system.
What encloses the whole embryo?
The embryo is enclosed in a thin cellar membrane called the amnion.
What happens when the larva bursts the amnion?
The chorion disappears, possibly digested by larval enzymes.
