The ontogeny of an organism is a complex process that strongly depends on the timing of developmental processes. In this article, I discuss ontogeny of fish (and other organisms) in temporal terms, based on the hypothesis that organisms as self-organized entities may create their own times for their development, and that this development consists of a sequence of longer stabilized states (steps...

Background:Spermatogenesis is maintained by a pool of the spermatogonia. The group formed by As, Apr and Aal is known as undifferentiated type a spermatogonia (Aund). The Aal spermatogonia will differentiate, with no mitotic division, to the differentiating type A1 spermatogonia. The type A1 spermatogonia undergo 6 successive mitotic divisions to yield A2, A3, A4, intermediate-type (In), and ty...

allometric growth pattern and body shape changes of the green terror (andinoacara rivulatus)(cichlidae) were studied using landmark-based geometric morphometric (gm) and traditional methods, from hatching up to 1266 hours post hatching (hph) under culture conditions. the left side of specimens were photographed using digital camera and morphometric characters, including total length, head lengt...

Abstract Cetaceans (baleen and toothed whales) present a unique set of adaptations for life in water. Among other abilities, the two living groups can hear produce different sound frequencies: baleen whales use low frequencies primarily communication, whereas acquired ability to echolocate using high-frequency sounds. Both exhibit modifications morphology ear bones (tympanic bulla periotic) tha...

Zebrafish exhibit remarkable alterations in behaviour and morphology as they develop from early larval stages to mature adults. In this study we compare the locomotion parameters of six common zebrafish strains from two different laboratories to determine the stability and repeatability of these behaviours. Our results demonstrate large variability in locomotion and fast swim events between str...

Basidiocarps of species of Armillaria, Russula, Lactarius and  Agaricus with fungal infection were collected from different regions of Iran. Portions of infected carpophores, were taken and cultured on PDA, PCA and MEA. Fungicolous isolates were identified on the basis of morphological characters such as: color and shape of colony, morphology and branching of conidiophores, manner of proliferat...

Drawing on both evolutionary and ontogenetic perspectives, the basic biological-genetic and social-cultural architecture of human development is outlined. Three principles are involved. First, evolutionary selection pressure predicts a negative age correlation, and therefore, genome-based plasticity and biological potential decrease with age. Second, for growth aspects of human development to e...

Developmental research has the potential to address some of the critical gaps in our scientific understanding of the role played by cultural learning in ontogenetic outcomes. The goal of this special section was to gather together leading examples of research on cultural learning across a variety of social contexts and caregiving settings. Although the field of developmental psychology continue...