What's the difference between heterochrony and ontogeny?
Heterochrony
Definition:
(n.) In evolution, a deviation from the typical sequence in the formation of organs or parts.
Example Sentences:
(1) A detailed analysis of the frontal, medial prefrontal and hippocampal regions also shows a heterochrony within these regions.
(2) These groups correspond to different stages of neuroblast development in vivo and their presence in the tissue cultures of different brain regions reflects the heterochrony of cell development in these regions.
(3) Direct development is achieved primarily by heterochrony, that is, by the abbreviation or elimination of larval developmental processes and the acceleration of processes involved in development of adult features.
(4) Ontogeny in the tube-crested dinosaur Parasaurolophus (Hadrosauridae) and heterochrony in hadrosaurids.
(5) The concepts of chronogenetics, heterochrony, and developmental field defects appear relevant to yet another set of patients with chromosome anomalies.
(6) It has been pointed out, that there is a complex heterochrony of regional development in the brain.
(7) Certain single malformations such as holoprosencephaly immediately suggest heterochrony by their resemblance to antecedent phylogenetic or embryologic structures.
(8) Some male sterile mutations can decouple the development of the different components of a germ cell, i.e., they may lead to a heterochrony of the development of the different subcellular structures, or they may permit the differentiation of some components of a germ cell even in the complete absence of an organelle.
(9) He has only mentioned the concept of heterochrony to which we give much more importance nowadays.
(10) The role of altered developmental timing or heterochrony in morphologic evolution has intrigued classical and modern biologists.
(11) During prenatal life of monkey and man in the development of the frontal area the phenomena of heterochrony (common for both species) and anabolia (peculiar for man only) are observed (the appearance of new more complex structures).
(12) It is theorized that hormones are a major factor in the non-random regulation of cellular heterochrony in tumourigenesis.
(13) The data obtained suggest a heterochrony and different rate of the functional callosal connexions maturation in projection and associative areas of the cortex.
(14) The perspective of heterochrony stresses the molecular history and hierarchy which is recapitulated with each pregnancy, and reconciles apparent discrepancies between the rates of molecular and morphologic evolution.
(15) In terms of heterochrony such a pattern most likely is the result of a process termed "acceleration", i.e.
(16) Notwithstanding this, gross regularities of heterochrony in the neurogenetic behavior of the different segments lead to a definition of elemental longitudinal compartments of the forebrain and mesencephalon (floor, paramedian, basal, and alar regions) on the basis of precocious differentiation of the basal region and retarded differentiation of the paramedian and alar regions.
(17) Molecular mechanisms underlying heterochrony are thereby described.
(18) We propose that such a shift in relative timing of the developmental phenomena involved inhibits pigment cell migration in embryos of the white axolotl mutant and, accordingly, that the restricted pigmentation of the mutant larva is generated through heterochrony.
(19) In its normal ontogeny, Hydractinia symbiolongicarpus, a closely related hydractiniid hydroid, not only shows morphological heterochrony similar to that induced in P. carnea by DNP, but also shows a pattern of gastrovascular flow similar to that observed in P. carnea under treatment with DNP.
(20) In view of elucidating the origin of this heterochrony, we make an electrophoretic study of the different extracts from juveniles, adults in activity, in natural sleep and awakning.
Ontogeny
Definition:
(n.) The history of the individual development of an organism; the history of the evolution of the germ; the development of an individual organism, -- in distinction from phylogeny, or evolution of the tribe. Called also henogenesis, henogeny.
Example Sentences:
(1) The effects of postnatal methyl mercury exposure on the ontogeny of renal and hepatic responsiveness to trophic stimuli were examined.
(2) These results suggest that ED2+ macrophages, TRPM-3+ macrophages, and Ia+ dendritic cells are distinct cell lines that pursue independent developmental process in spleen ontogeny.
(3) We have studied the postnatal ontogeny of creatine kinase (CK) and the glycolytic enzymes phosphoglycerate kinase (PGK), phosphoglycerate mutase (PGM), enolase (En), and pyruvate kinase (PK) in rat brain and uterus.
(4) Experiments were conducted in a group of pigs to determine the ontogeny of antigen specific IgA in the trachea.
(5) More and more of ontogeny has been taken over for eruption.
(6) The results suggest that normal development of some invertebrate neural pathways may be more dependent on experience during ontogeny than has previously been assumed.
(7) During ontogeny, the number of these cells gradually increased.
(8) In studies of the ontogeny of fibroblast-epithelial interactions during late fetal lung rat lung development, we have identified two subpopulations of fibroblasts which differed in their ability to promote epithelial cell proliferation or differentiation.
(9) In ontogeny, Ia+ dendritic cells were not stained with ED2 or TRPM-3.
(10) This difference was observed throughout ontogeny up to 15 mo of age, and was associated with increased levels of IL 2 activity in the culture supernatants.
(11) The present study investigated the ontogeny of 3H-uridine incorporation into RNA as a measure for RNA synthesis in preimplantation porcine embryos from the two-cell stage up to the stage of the newly hatched blastocyst.
(12) Recent advances in hybridoma technology and cellular immunology have facilitated the understanding of the ontogeny, structure, and function of the avian immune system.
(13) The present study was undertaken to assess the functional ontogeny of alpha 2-noradrenergic receptors in the hypothalamic paraventricular nucleus (PVN) that mediate noradrenergic stimulation of feeding in the rat.
(14) The heterogenous ontogeny and binding characteristics of brain and liver T3NR is compatible with the hypothesis that different thyroid hormone receptors are expressed in these tissues.
(15) Furthermore, it can be suggested that the onset may even be in the fetal stage and that lesions of specific neuronal systems occurring in early ontogeny could result in specific abnormality in the higher system which manifest later in development, after these structures reach certain levels of maturation.
(16) In three experiments, the effects of augmenting or blocking dopamine (DA) D-2 receptor activity on the ontogeny of response suppression learning of preweanling rat pups were determined.
(17) Kupffer cells in the liver and endothelial cells of blood vessels stained positively for the enzyme at every stage of ontogeny studied.
(18) The axonal amelin antibody detects a 97 kDa protein in embryonic tissue which diminishes during development; and a 93 kDa protein which is first seen at postnatal day 1 of mouse brain ontogeny, increasing constantly to its adult concentrations.
(19) The expression of T-cell antigen receptors during T-cell ontogeny is an important issue that bears directly on such questions as where T-cell tolerance is acquired, at what stage T cells become susceptible to repertoire selection, and why most thymocytes die within the thymus.
(20) Most importantly, our hypothesis leads to a series of experimentally testable predictions, which should provide considerably greater insight into the ontogeny of NK cells and their relationship to the T-cell lineage.