Reproductive Terminology

Scientists can use this table of standardized reproductive terms and definitions to more effectively communicate about reproductive research.

An emerging issue in applied fisheries reproductive biology is the need for common terminology. Many of the terms used to describe reproductive concepts and developmental stages are often inconsistent and specific to a study, species or region. This makes communication and comparative analyses difficult for researchers. In an effort to address the need for a common vocabulary, a group of biologists developed a list of commonly used reproductive terms and definitions (Lowerre-Barbieri et al. 2011) and standardized terms to describe reproductive development (Access publication: Brown-Peterson et al. 2011). 


Reproductive Terms and Definitions

Term Definition References


Development and growth of oocytes, from oogonia through maturation. Stages of oogenesis: oogonia (Oo); primary growth (PG); cortical alveolar (CA); vitellogenic (Vtg), also known as yolked (Yo); and oocyte maturation (OM).

Kjesbu 2009

Wallace and Selman 1981

Patiño and Sullivan 2002

Hunter and Macewicz 1985


Morphological and physiological changes during development of male germ cells. Stages of spermatogenesis: spermatogonia (Sg), spermatocytes (Sc), spermatids (St) and spermatozoa (Sz). 

Grier and Uribe-Aranzábal 2009

Nagahama 1983

Primary growth

Gonadotropin-independent growth of oocytes, characterized by basophilic staining. Stages include: single nucleolus, multiple nucleoli and perinucleolar.

Wallace and Selman 1981

Secondary growth 

Gonadotropin-dependent growth of oocytes. Stages include: cortical alveolar (CA) and vitellogenic (Vtg). Vtg is often divided into three substages: primary vitellogenic (Vtg1), secondary vitellogenic (Vtg2) and tertiary vitellogenic (Vtg3).

Luckenbach et al. 2008

Abascal and Medina 2005

Matsuyama et al 1990

Oocyte maturation (OM)

Resumption of meiosis and achievement of oocyte maturational competence, ending in ovulation. OM includes two nuclear events: germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD). In some species, OM may also include: formation of large oil droplets, known as lipid coalescence (LC); yolk coalescence (YC); and hydration (H).

Grier et al. 2009

Jalabert 2005

Reproductive phases 

Phases of gonadal development occurring in all fishes prior to, during and after spawning. Phases are defined as: immature (Imm); developing (Dev); spawning capable (SC), which includes the spawning (S) subphase; regressing (Rgs); and regenerating (Rgn).

Brown-Peterson et al. this 2011

Determinate fecundity

Recruitment of oocytes from primary growth to secondary growth occurs prior to an individual’s spawning period.

Hunter et al. 1992

Murua and Saborido-Rey 2003

Indeterminate fecundity

Recruitment of oocytes from primary growth to secondary growth continues throughout an individual’s spawning period.

Hunter et al. 1992

Murua and Saborido-Rey 2003

Batch spawner

Females capable of ovulating and spawning multiple batches of oocytes during the individual spawning period. Batch spawners can have determinate or indeterminate fecundity.

Murua and Saborido-Rey 2003

Total spawner

Females ovulate and spawn all developing oocytes in a single event or within a very short time period as part of a single episode.

Murua and Saborido-Rey 2003

Skipped spawning

Sexually mature fish that fail to spawn during a reproductive season. Failure to spawn can be recognized by a lack of ovarian development (vitellogenesis) or by massive atresia prior to the spawning period.

Rideout et al. 2005


Synonymous with sexual maturity in both males and females, which is attained once in a lifetime.

Rideout et al. 2005

From Lowerre-Barbieri et al. 2011

FWC Facts:
Gar and bowfin, or mudfish, have specially adapted swim bladders that allow them to gulp air at the surface when oxygen levels are low.

Learn More at AskFWC