Quantitative anatomical studies on the postnatal development of the cerebellum of the albino rat

Abstract

Summary.The quantitative postnatal changes of the cerebella of 65 Wistar rats aged 2-120 days have been examined. The cerebellar volume increases in two phases: The first phase lasts from birth to the seventh postnatal week. The second phase begins ten weeks post parturn and lasts for a Ionger period than the first phase.The cerebellar surface increases continuously from birth to the end of the seventh week.The volume of the external granular layer is maximal when the organ grows rapidly. The external granular layer has nearly disappeared 24 days after birth; the volume of the interaal granular layer is maximal at this time. Later on, the volume and the width of the interaal granular layer decrease. Myelinization of the cerebellar fibers and growth of the molecular layer run parallel to this decrease. The second late, but protracted growth of the cerebellum, ten weeks after birth, is due to an increase of the molecular and medullary layer. These findings are in good accord with histological, histochemical, and ultrastructural observations of other authors.

Developmental fates and migratory pathways of dividing progenitors in the postnatal rat cerebellum

“…Postnatal day 415 rats were selected as the starting point for this study because 1) the size of the rat cerebellum of earlier stages is too small to manipulate easily; 2) the foliation of the cerebellum is not yet fully developed (Heinsen, 1977), thus allowing us to inject into the WM more easily; and 3) the generation of glia has begun, based on previous 3H-thymidine studies (Miale and Sidman, 1961;Fujita et al, 1966). between folia and the deep cerebellar nuclei.…”

Anomalous migration of central nervous tissue to transplanted autonomic ganglia

“…At this age the cerebellum should have a mature appearance. All of the EGL cells normally descend to the IGL level by the 24th day of postnatal life (Heinsen, 1977). Instead, numerous cells of the EGL were clustered at the transplantation site as laminae directly beneath the pial surface.…”

Development of the Cerebellum in the Platypus <b><i>(Ornithorhynchus</i></b> <b><i>anatinus)</i></b> and Short-Beaked Echidna <b><i>(Tachyglossus aculeatus)</i></b>

“…The similarities in the timing of cere bellar development between the monotremes and both polyprotodont (Virginia opossum, Didelphis virginiana ) [King et al, 1987;Laxson and King, 1983;Maley and King, 1980] and diprotodont (tammar wallaby, Macropus eugenii ) [Ashwell, 2010] metatheria are clear and have two significant aspects ( table 4 ): (1) the ntz and ctz appear either shortly before hatching or around the time of birth in monotremes and metatheria, whereas the ntz and ctz emerge during the embryonic period in the eutheria; (2) the egl persists for up to 3 or 4 months of postnatal life and there is a prolonged period of granule cell generation in both monotremes and metatheria, whereas the egl persists for less than 4 weeks in rodents [Heinsen, 1977], although it persists for months postnatally in humans [Friede, 1973;Rakic and Sidman, 1970]. On the other hand, the monotreme cerebellum is slightly advanced at hatching compared to the newborn metatheria in that the ntz and ctz are already evident by the last third of incubation ( fig.…”

“…6 d). King et al, 1987;Laxson and King, 1983;Maley andKing, 1980. b Ashwell et al, 2010. c Altman and Bayer, 1978a, b, 1985a, b, 1987aHeinsen, 1977. Note that developmental ages cited by Altman and Bayer are based on E1 being the first day after conception.…”