Reproductive Anatomy Flashcards
Describe the Spermatheca and accessory glands as well as their functions
Outpocketing of oviduct or vagina is spermatheca
- Stores sperm prior to fertilization: survival variable – multiple years in social insects!
- Spermathecal gland provides nourishment to sperm
- Pair of accessory glands opening into vagina • secretion of sticky ‘cement’ to attach eggs to substrate
- protection of eggs
- produce venom in Hymenoptera (e.g. parasitoids, bees)
Describe the male reproductive system and the associated functions
Production, storage and delivery of sperm
- Two testes with follicles where spermatogenesis occurs
- Mature sperm pumped into vas deferens then to ejaculatory duct & aedeagus
- Seminal vesicles store sperm
- Accessory glands add nutrient-rich secretions to sperm for long-term survival in female
- Accessory gland secretions tightly coordinated with mating behaviour & regulated by hormones (Diptera use a secretion to induce female
Describe the insect circulatory system
- Open system – blood (hemolymph) directly bathes internal organs in body cavity (hemocoel)
- Only contractile structure and conducting tube is dorsal vessel
- Circulatory system & hemolymph : variety of vital functions
- Consists of a fluid or plasma portion and cellular portion : hemocytes
Elaborate on hemolymph and give some basic functions
Extremely dynamic fluid; changes with diet, environment & life history stage
- Plasma portion is 85% water – hemolymph has several functions:
- Acts as a hydrostatic skeleton – combo. of muscles & hemolymph pressure changes for locomotion, molting, reproduction, metamorphosis
- Transport & storage of nutrients (amino acids, sugars, fatty acids) • Hormone transport
- Immunity
What is the main carbohydrate in insect hemolymph?
Trehalose
• Disaccharide made of 2 glucose molecules (twice as much energy)
Relatively, do insects or vertebrates have the most free amino acids?
- Insects have > 300X free amino acids in hemolymph as in vertebrates
- Serves as a reservoir for protein synthesis for construction of new cuticle
How are mountain pine beetles able to survive freezing temperatures?
A hemolymph nutrient “glycerol”. Produced in increased concentrations in the fall and gives the hemolymph the ability to drop below 0 without causing ice formation and necrosis.
Describe the insect fat body in detail
- Loose network of cells & connective tissues suspended in hemolymph in hemocoel (up to 60% of insect’s biomass!) • Several functions of fat body:
- Multiple metabolic functions – storage & synthesis of fats; metabolism of sugars
- Major site of glycogen deposition & storage
- Synthesis & secretion of hemolymph proteins (e.g. yolk protein (vitellogenin))
Is the fat body static?
No it can switch activity in response to nutritional and hormonal signals.
- Vital in order to regulate insect growth, metamorphosis and reproduction
- E.g., Oogenesis, vitellogenesis & integration of fat body and midgut physiology with neuroendocrine control by hormones
How does gas exchange occur in insects?
Open tracheal system: connected to exterior via spiracles
• Tracheal tubes branch into minute tracheoles in metabolically active tissues where gas exchange occurs by diffusion. Huge surface area.
Describe the female reproductive system with respect to the ovaries the and their associated functions.
- Paired ovaries made up of ovarioles : site of egg formation and maturation (oogenesis).
- Ovarioles surrounded by follicular epithelial cells : uptake of nutrients from hemolymph for yolk production (vitellogenesis) and secretion of egg shell
- Oogenesis and vitellogenesis under endocrine control
