#reproduction

• Acrocyst — A temporary spherical anatomical structure or protective vesicular sac formed during the reproduction of certain colonial hydrozoans, protecting eggs or planulae.
• Agamous — Reproducing without sexual cells or fertilization; a plant or animal organism whose multiplication is achieved asexually, through cell division, budding, or spores. In a general sense, it describes the structural biological process that does not involve the alternation or fusion of gametes.
• Agamete — An asexual reproductive cell (such as a spore, zoospore, or conidium) capable of directly giving rise to a new living organism without previously fusing with another sexual cell. Its functional structure is specific to lower plants, fungi, and protozoans that utilize alternation of generations in their biological cycle.
• Agametangia — A rare plural or adjectival form used in botany to denote asexual organs or cellular structures inside which agametes (spores or zoospores) are formed in lower plants, fungi, or algae. The term describes the non-sexual reproductive apparatus before modern morphological standardization.
• Agamete — A primitive reproductive cell form or an undifferentiated gamete that develops directly, without fertilization, giving rise to a new organism. It represents a biological unit of asexual reproduction, found in certain protozoans, algae, and lower fungi, where multiplication does not involve the fusion of complementary genetic material.
• Agamic — Reproducing without the intervention of sexual cells or the process of fertilization; independent of gametic genetic phenomena. In a structural sense, the term describes organisms, evolutionary phases, spores, or multiplication methods (such as budding or direct division) that perpetuate the species exclusively asexually, generating clones identical to the parental organism.
• Agamogenetic — Relating to agamogenesis; pertaining to or specific to asexual reproduction, carried out independently of gametic fusion or the recombination of genetic material. In a structural sense, the term describes cellular processes, ontogenetic development cycles, and biological replication mechanisms through which a new organism originates from a single parental cell without meiotic division.
• Agamogenesis — A form of asexual reproduction in which the development of a new organism occurs without the participation of sexual cells (gametes) and without the process of fertilization; a mode of structural biological multiplication found in protozoans, coelenterates, worms, and certain lower plants. This phenomenon includes varied methods such as direct division, budding, or mitotic sporogenesis, guaranteeing the faithful perpetuation of the parental genome.
• Allelogamy — A biological phenomenon or mode of reproduction found in plants, consisting of cross-pollination between different individuals belonging to the same species; reciprocal fertilization. Structurally, allelogamy ensures the maintenance of heterozygosity and genetic recombination, being a crucial evolutionary mechanism that enhances the viability and adaptability of offspring compared to self-pollination.
• Allogamous — A term describing a plant organism or a species that reproduces exclusively or predominantly through cross-fertilization (allogamy), meaning the union of gametes originating from different individuals. In a structural sense, allogamous plants have developed complex adaptive morphological and physiological mechanisms (such as self-incompatibility, dioecy, or protandry) to prevent self-pollination and ensure high genetic variability.
• Allogamous — Relating to plants, flowers, or vegetal species: reproducing via cross-pollination, a biological phenomenon where fertilization is achieved using pollen from another flower belonging to either the same individual or a different individual of the same species. This complex genetic mechanism prevents inbreeding, promotes hereditary variability, and enhances the descendants' adaptability to environmental shifts.
• Amphigamy — A mode of reproduction characteristic of cryptogamous plants, defined by the absence of obvious floral organs and the occurrence of fertilization through the union of simple gametes or hidden spores; also, in an extended biological sense, it can designate the symmetrical cellular fusion or direct hybridization between two genetic lines without macro-structural sexual differentiation.
• Amphigenetic — Relating to amphigenesis or originating from it; characterized by biparental sexual reproduction involving the hybrid fusion of two gametes of different sexes (male and female). From a structural perspective, it describes the normal ontogenetic process through which the new organism inherits complementary sets of genetic material from both parents, ensuring genomic variability within the species.
• Amphigenesis — A biological process of generating or arising a new organism through true sexual reproduction, requiring the equal participation and structural fusion of male and female reproductive elements (gametes). This phenomenon represents the evolutionary foundation of most higher organisms, being the opposite of asexual reproduction or clonal parthenogenesis.
• Amphigony — A normal form of biparental sexual reproduction requiring the structural and functional fusion of two gametes of opposite sexes, male and female, leading to the formation of a diploid zygote. This fundamental biological process represents the evolutionary basis of genetic variability within higher organisms, being the opposite of parthenogenesis or clonal asexual reproduction.
• Amphimixis — A fundamental biological process of true sexual reproduction, consisting of the structural fusion of two gametes of opposite sexes (the male and female pronuclei), leading to the formation of a diploid zygote (fertilized egg). This mechanism forms the basis of Mendelian genetic recombination, ensuring the transmission of parental hereditary traits and genomic diversity within the species.
• Amphitoky — A specialized form of deuterotokous parthenogenesis in which unfertilized eggs can spontaneously develop into individuals of both sexes (both males and females). This structural reproductive mechanism is encountered in certain insect species (such as some aphids or wasps) and represents a biological adaptation strategy for dynamic population regulation in the absence of amphimictic reproduction.
• Amphitoky — A rare form of parthenogenesis, equivalent to amphitoky or deuterotoky, through which unfertilized eggs can develop into individuals of both sexes (both males and females). This phenomenon represents a remarkable evolutionary adaptation found in certain arthropods, providing demographic balance to isolated populations by alternating genetic sex-determination mechanisms without male gametic contribution.
• Amitotic — Pertaining to amitosis or occurring through amitosis; relating to direct cell division, characterized by the simple cleavage of the nucleus and cytoplasm without the individualization of chromosomes and without the formation of the mitotic apparatus (spindle). This physiological structural mechanism is specific to certain specialized, aged, pathological cells or lower unicellular organisms.
• Amitosis — A form of direct cell division occurring through the simple cleavage, strangulation, or fragmentation of the nucleus and cytoplasm, without the individualization of chromosomes and without the formation of the mitotic apparatus (spindle). This physiological structural mechanism is considered a rudimentary method of multiplication, being specific to certain aged, specialized, or pathological cells in higher organisms, as well as many lower unicellular organisms.