Insect Reproductive Anatomy Quiz

Reproduction

• Reproduction is the production of offspring via a sexual or asexual process.

Reproduction Strategies

Asexual Reproduction

• Requires only one parent organism.
• Common in invertebrates.
• Methods include fission, budding, fragmentation, and parthenogenesis.

Sexual Reproduction

• Requires two parent organisms (male and female).
• Involves fusion of male (sperm) and female (egg) gametes to form a zygote.

Mechanisms of Asexual Reproduction

• Fission: Separation of a parent into two or more individuals of similar size.
• Budding: A parent organism develops a bud that grows and eventually separates.
• Fragmentation: A parent organism breaks into fragments, each of which develops into a new organism.
• Parthenogenesis: Development of an egg without fertilization.

Sexual Reproduction

• Two parents.
• Each parent has reproductive organs to produce gametes (reproductive cells).
• Males have testes producing sperm.
• Females have ovaries producing ova (eggs).

Reproduction Strategies: Additional Points

• Internal vs. external fertilization.
• Semelparity: Organisms reproduce only once in their lifetime before death (e.g., octopus, mayfly).
• Iteroparity: Organisms reproduce multiple times over their lifetime (e.g., most animals).

External Fertilization vs. Internal Fertilization

• External: Eggs shed by the female are fertilized by sperm in the external environment.
• Internal: Sperm are deposited in or near the female's reproductive tract, and fertilization occurs within the tract.

Reproductive Cycles and Patterns

• Most animals exhibit cycles in reproductive activity related to changing seasons.
• Reproductive cycles are controlled by hormones and environmental cues.

Hermaphroditism & Alternation of Sexes

• Simultaneous hermaphroditism: Both gametes are present. Self-fertilization is possible.
• Sequential hermaphroditism: Change in sex over time. Protandrous (male first, then female).
• Examples include: Bluehead wrasse.

Liver Fluke (Sexual and Asexual Reproduction)

• This organism exhibits both sexual and asexual reproduction.
• Shows the anatomy of the organism with specific organ identifications.
• Exhibits both male and female reproductive organs

Female Gametes - Reproduction Types

• Oviparity: Eggs are laid outside the body.
• Ovoviviparity: Eggs hatch inside the mother's body. Nutrients are stored in the egg.
• Viviparity: The embryo develops inside the mother. Nutrients come from the mother (e.g., all mammals except monotremes).

Insects

• Complex reproductive systems.
• Males and females are separate, with specific reproductive organs.

Mammalian Reproduction: Males

• Male gonads (testes).
• Seminiferous tubules form sperm.
• Sperm pass through the epididymis.
• Sperm are propelled during ejaculation through muscular vas deferens, ejaculatory duct, and urethra.

Spermatogenesis

• Process of sperm production in males.
• Involves mitosis and meiosis.
• Stages include spermatogonia, primary spermatocyte, secondary spermatocyte, spermatid, and sperm.

Accessory Glands

• Contribute fluids to semen (important for sperm function).
• Three sets: seminal vesicles, prostate gland, and bulbourethral glands. -Functions, including contributing fructose and other energy sources and buffering the semen.

Female Reproductive Organs: Ovary

• The female gonads. Located in the abdominal cavity.
• Each ovary contains follicles, each with an egg.
• Ovulation: Release of an egg from the follicle.

Oogenesis

• Process of egg (ovum) production in females
• Stages: Oogonium, primary oocyte, secondary oocyte, ovum.

Oogenesis (Further Details)

• Oogonia divide by mitosis in fetal ovaries.
• Primary oocytes complete meiosis I when the egg is ovulated.
• Meiosis II is completed if/only if fertilization occurs
• Hormonal control
• Structures like follicles.

Ovaries - Hormones

• Estrogen: Involved in ovulation and pregnancy.
• Progesterone: Prepares the uterus for pregnancy.

Oviducts and Uterus

• Oviducts (Fallopian tubes) convey the egg to the uterus.
• Contain cilia that move the egg.

Ovarian Cycle

• Ovulation marks the end of the follicular phase and the start of the luteal phase.
• Stages include follicular phase, ovulation, and luteal phase. Controlled by hormones.

Luteal Phase

• Corpus luteum forms from ruptured follicle.
• Secretes progesterone and estrogen, supporting pregnancy.
• Failure of fertilization leads to corpus luteum degeneration.

Fertilization

• Acrosome reaction: Sperm penetrates egg's membrane.
• Calcium release: Activates egg for fertilization.
• Membrane changes: Prevent additional sperm entry.

Gamete Production: Meiosis

• Oogenesis: Formation of female gametes (ova).
• Spermatogenesis: Formation of male gametes (sperm).
• Meiosis is crucial in both processes for producing haploid gametes
• Involved stages like mitosis, meiosis I, and meiosis II for both ova/oocytes and sperm.

Revision Questions

• Forms of asexual reproduction.
• Process of oogenesis and ovulation.
• Human male's reproductive organs (external and internal).

Acknowledgements

• Credits: Campbell's Biology and Dr. Javier delBarco-Trillo for contributions to the materials.