Development of cerebral sulci and gyri in fetuses of cynomolgus monkeys (Macaca fascicularis)

Abstract

This study aimed to clarify the development of sulci and gyri on the external surface of the cerebrum of cynomolgus monkeys. Sulcus formation began with the appearance of the lateral fissure on embryonic day (ED) 70, followed by delineations of four cerebral lobes by the emergence of the parietooccipital sulcus, central sulcus, and preoccipital notch on EDs 80-90. The following primary sulci were then visible until ED 120: the superior temporal sulcus on ED 90; the intraparietal sulcus, lunate sulcus, inferior occipital sulcus, and arcuate sulcus on ED 100; and the principle sulcus on ED 110; the occipitotemporal sulcus, anterior middle temporal sulcus, and superior postcentral dimple on ED 120. These sulci demarcated the superior temporal gyrus on ED 90, the precentral gyrus, supramarginal gyrus, and angular gyrus on ED 100, and the inferior and middle temporal gyri, postocentral gyrus, superior parietal lobule, superior, middle and inferior frontal gyri, and inferior occipital gyrus on ED 120. Except for the intermediate and lateral orbitofrontal sulci, the sulci that appeared on ED 130 and thereafter were not related to the gyrus demarcations. Intriguingly, the brain markedly gained weight on EDs 100 and 120, corresponding to the embryonic ages when almost all gyri were visible. The results suggest that a rapid growth of the cerebrum involves convolutions of the gyri by a regular sequence of the sulcus formation in cynomolgus monkeys. This study further provides a standard of reference for normal development in the cerebral cortical morphology of cynomolgus monkeys.

Development of cerebral sulci and gyri in fetuses of cynomolgus monkeys (Macaca fascicularis). II. Gross observation of the medial surface

“…7.4 in our previous study (Fukunishi et al 2006). Photographs of the medial surface of the cerebrum were taken, and tracings were made from the photographs of the outlines of the perimeter of the hemisphere and of the sulcal patterns at each age.…”

“…Photographs of the medial surface of the cerebrum were taken, and tracings were made from the photographs of the outlines of the perimeter of the hemisphere and of the sulcal patterns at each age. According to the procedures of our study (Fukunishi et al 2006), the degree of sulcal formation was graded three as shown in Fig. 1, with its chronological order appearing in Table 1.…”

“…Since the calcarine sulcus extends from the splenium of corpus callosum to the end of the occipital lobe, the length of this sulcus reflects the size of the ''occipital region'', which includes the posterior part of the parietal lobe and Infolded and open groove, Grade 3 Infolded and closed groove. This illustration was reproduced from our previous study (Fukunishi et al 2006) the occipital lobe. The lengths of these sulci and the FO line were measured on photographs of the medial aspect of cerebrum by Tamaya Digital Area-Line Meter Planix 10 s (Tayama Technics Inc, Tokyo, Japan).…”

“…Imagawa and Yamadori (1996) measured the lengths of cingulate and calcarine sulci of four species of adult primates, and revealed that the ratios of these sulcal lengths to a fronto-occipital (FO) length reflected the sizes of the ''frontoparietal region'', which included the frontal lobe, the anterior part of the parietal lobe and the limbic cortex, and the ''occipital region'', which included the posterior part of the parietal lobe and the occipital lobe, respectively. Our previous study reported that the formations of almost all primary sulci and gyri on the lateral and ventral cerebral surfaces were correlated with the brain weight gain in cynomolgus monkeys (Fukunishi et al 2006). However, we did not clarify the sulcal and gyral formations on the medial cerebral surface and the relationship between the regional development of the cerebrum and formations of the sulci and gyri.…”

“…In humans, chronological sequences of the appearances of the cerebral sulci and gyri have been well documented in anatomic (Turner 1948;Chi et al 1977;Dorovini-Zis and Dolman 1977;Naidich et al 1994), sonographic (Murphy et al 1989;Huang 1991;Naidich et al 1986;Worthen et al 1986;Naidich et al 1994), and magnetic resonance image (MRI) (Martin et al 1988;Naidich et al 1994;van der Knaap et al 1996) studies. Recently, we have reported a chronological order in the appearance of cerebral sulci and gyri on the lateral and ventral surfaces and its relation to brain weight gain in cynomolgus monkeys (Fukunishi et al 2006). Cingulate sulcus and calcarine sulcus are phylogenetically highly-conserved cerebral sulci among primates.…”