Reproductive biology

Gastrotrichs are primitively hermaphroditic, with frequent protandry (male organs develop first). Most species possess paired testes and ovaries. Loss or reduction of the testes is common in several lineages. (Some Thaumastodermatidae have lost the left testis, for example, and many Chaenotonotida have reduced testes). The ovary is single in species of Lepi-dodasyidae. Fertilization is via indirect transfer of sperm or spermatophores. Complex reproductive organs may facilitate transfer of sperm in some species. Development is direct with no larval stage. Freshwater chaetonotidans often are partheno-genetic, with a later hermaphroditic phase.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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