Table 1 Similarities between NPPa of teleosts and mammalian AVPV

Neuroanatomical location

Anteroventral preoptic area, around the preoptic recess [2, 7, 31, 38].

Ventral position in the periventricular zone of the preoptic nucleus [68].

Dopamine (tyrosine hydroxylase) neurons

Contain several DA neurons [7, 8, 12, 13, 39, 47] and serve as an important DAergic neuronal group involved in the regulation of gonadotropin secretion and reproduction [2, 15, 37, 39].

Contain several neurons and serve as a nodal component of neural circuitry controlling gonadotropin secretion [68].

Estrogen receptor (ER) expression

Presence of ERα as well as ERβ expression was observed [11, 12, 69, 70].

Contains both ERα and ERβ [23, 74, 75].

TH neurons expressing ER

Several TH neurons co-express ER [11, 12].

Harbors TH neurons expressing ERα [75] and ERβ [23].

Sexually dimorphic TH neuronal number

Higher in females compared to that in males (present study).

Higher in females compared to that in males [23, 24, 76].

Kisspeptin-containing system

kiss 2 neurons were seen in the POA [71] at a similar location to the NPOav, and these neurons seem to co-express ER [72]. POA kiss neurons are regulated by gonadal steroids [82; 83].

Harbors kiss 1 neurons [78]; these neurons co-express ER and are regulated by gonadal steroids [79].

Cocaine- and amphetamine-regulated transcript (CART) neurons and fibers

Few CART cells but several fibers [73].

Few CART cells and dense CART innervation [77].

NPY neurons and fibers

Few NPY cells and several fibers [8].

NPY cells and fibers were seen in and around AVPV [80].