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, 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.
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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.
What is the primary organ for excretion of nitrogenous substances in adult honey bees?
The primary organ for excretion is the Malpighian tubules, of which there are around 100 in the abdomen.
What is the structure of a Malpighian tubule?
Each Malpighian tubule consists of a single layer of cells attached to a thin basement membrane, with muscle fibers and tracheoles supplying oxygen.
What is the function of microvilli in Malpighian tubules?
The microvilli are microscopic projections tightly packed together inside the tubule, aiding in absorption.
How do Malpighian tubules connect to the digestive system?
The open ends of the Malpighian tubules link into the digestive system just above the pyloric valve leading to the small intestine.
How are substances filtered in the Malpighian tubules?
Substances in the haemolymph are filtered through the wall of a Malpighian tubule at its upper end, passing through gaps between cells.
What happens to water and minerals during excretion?
Some water, along with minerals and salts, is re-absorbed back into the haemolymph to maintain balance.
What determines whether substances are reabsorbed or excreted?
It depends on the needs and balance of the system; the same substances can be filtered out or reabsorbed at different times.
How are other substances secreted in the Malpighian tubules?
Other substances are actively secreted by the cells, pulled in and passing into the lumen of each tubule.
Where does absorption and reabsorption occur in the Malpighian tubules?
Absorption and reabsorption occur in the lower (proximal) end of the tubule.
What happens to waste material after leaving the Malpighian tubules?
Waste material passes into the Ventriculus, through the small intestine and rectum, and leaves the body via the anus.
What occurs while waste passes through the intestine and rectum?
More water may be absorbed from the gut contents during this passage.
What is the normal form of nitrogenous waste excreted by honey bees?
The normal form of nitrogenous waste excreted is uric acid, along with various salts and harmful substances.
Why is ammonia considered toxic for honey bees?
Ammonia is toxic and requires a lot of water to remove it from the body.
