It has long been known that the left and right hemispheres of the human brain show different morphology related to their functions in the human body, with this being referred to as asymmetry or hemispheric asymmetry [1]. The earliest evidence of asymmetry comes from the observation of clinical patients with focal cerebral injury. In 1860, Paul Broca found that damage to specific areas (over part of the inferior frontal gyrus) of the left hemisphere could cause aphasia, although this did not happen when similar damage occurred on the right side [2]. Since then, more and more evidence has revealed functional differences between the left and right hemispheres of the human brain [3–6]. The most fundamental reason for the functional differences of the brain is differences in the organization of structures between the left and right hemispheres. To identify the organization and structural basis of the functional asymmetry of the human brain, studies have concentrated on the structural differences in the cerebral hemispheres, and have gradually revealed that multiple structures differ between the left and right hemispheres of the human brain [7–9]. In 2007, Amunts used MRI to measure the depth of the central sulcus (CS) of 103 healthy adults and showed significant differences between the left and right hemispheres of right-handed men, whose left CS was deep in the right side, whereas no obvious differences were found in women [10].
Obvious differences in brain function between men and women have long been found, and include cognitive processing, language, spatial imagination, and logical thinking [11–13]. These differences are also based on differences in the structures of the brain. In 1982, DeLacoste-Utamsing and Holloway published an article in SCIENCE magazine that proposed the existence of gender dimorphism in the morphology of the human corpus callosum [14]. Since then, more and more studies have suggested differences in multiple brain structures between men and women [15, 16], including a larger volume of gray matter along the CS in women than in men [17, 18].
However, there are few reports on the study of hemispheric asymmetries and gender dimorphism in the fetal human brain, and we are not aware of any reports of study of hemispheric asymmetries and gender dimorphism in the fetal CS [19].
To ascertain whether hemispheric asymmetries and gender dimorphism of the fetal CS exist in the early development period, this study obtained 7.0-T MRI data of the fetal CS from specimens ranging from 13 to 22 gestational weeks.
Using statistical methods, the condition of the hemispheric asymmetries and gender dimorphism of the fetal CS in the early development period were preliminarily judged, providing data that can further improve the understanding of the fetal brain in the early development period.