Gametogamy is sexual fusion – copulation orfertlization – of two single-celledgametes of different sex and the union of theirgametenuclei (and corresponding extranuclear structures) giving thezygote nucleus, as well as whole zygotic content.[1][2]
According to itsmorphology, size and other properties, most forms of gametogamy are as follows:
- Isogamy (Ancient Greek ισο -iso= "equal + γάμοςgámos = "marriage") – incell biology – is a type ofsexual reproduction that includesgametes of similar morphological similar shape and size, with difference in general only ingenome content andgene expression in one or moremating-type regions. Both gametes look alike, and they cannot be classified as "male" or "female." Actually, organisms characterized as isogametic have differentmating types, most commonly noted as "+" and "−" strains, although in some species there are more than two mating types (designated by numbers or letters). Izogamicfertilization includes two gametes fusion, when different mating types form azygote.[3]
- Heterogamy (Ancient Greek ἕτεροςheteros = "other, another" + γάμοςgámos = "marriage") – incell biology – is a synonym ofanisogamy, involving differently sized male and femalegametes produced by different sexes or mating types in aspecies.
- Apogamy (Ancient Greek αρο -apo = from, of + γάμοςgámos) – inbotany – is defined as a replacement of normalsexual reproduction byasexual propagation, withoutfertilization.[4] The fruits can be developed withoutfertilization. In this case,embryo occurs without fertilization or without the presence ofpollen. A special form of apogamia is when the embryo develops klijavo seed. It is the phenomenon calledparthenogenesis. So, fruits contain seeds, which although not fertilized, maintaining viability. In this case the embryo or germ arises from unfertilizedoocyte. This phenomenon is widespread example innuts.
From such seeds develop plants whose features are identical properties of mothers from which the seed was taken.
