title: [The morphological characteristics of the brain in 20- to 21-day-old embryos and 1- and 5-day-old rats].
abstract: Absolute and relative brain mass, specific rate of its growth, hemispheric cortex thickness, neurocyte distribution in the second and fifth cortical layers were investigated. A positive relationship between body mass and absolute brain mass was revealed in 21-day embryos and 1-day-old rats. Correlation coefficient between the values in 20-day embryos and 5-day-old rats was 0.2-0.3 (p > 0.05). All age groups showed a reliable correlation between relative brain mass and body mass. Both the parameters differed much in animals of the same age and sex and even within the same litter. Rate of brain growth was the highest during days 1-5 and the lowest between embryogenesis day 21 and day 1 of life, and higher in males than in females. Brain cortex was thicker in 5-day-old males than in females; this parameter varied within a wide range in all age groups. Neuron distribution density in the second layer decreased by the first day of life, that in the fifth layer by day 5 of life.
authors.forename: B Ia
authors.initials: BIa
authors.lastname: Ryzhavskiĭ
authors.forename: S I
authors.initials: SI
authors.lastname: Biriukova
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000196:embryology* / Q000254:growth & development; D005260:Female; D005865:Gestational Age; D006652:Histological Techniques; D008297:Male; D009929:Organ Size; D051381:Rats; D012727:Sex Characteristics
vernacular_title: Morfologicheskie osobennosti golovnogo mozga 20--21-dnevnykh émbrionov, 1- i 5-dnevnykh krys.