The present report describes a newborn calf with spina bifida that presented with a giant mass of the lumbar region, as well as subsequent gross, histological, and immunohistochemical examinations. A malformed Japanese black calf (estimated weight = 20 kg) was euthanized immediately after birth. A gross evaluation revealed a giant mass (approximately 60 cm × 30 cm × 15 cm) covered by the hair coat in the lumbar region and connected with the hair coat of the trunk. The mass surface was divided by a deep polygonal groove and externally resembled a lobulated kidney. Histology and immunohistochemistry revealed that the giant mass comprised a vessel, bronchiolus lined with cuboidal epithelium, and small alveolus. Bone bleaching revealed various abnormalities, including spina bifida, vertebral fusion, vertebral deformity, vertebral malformation, vertebral scoliosis, and coxal bone malformation. Following a suggestion that the giant lumbar region mass was occupied by lung tissue, this case was considered to involve an asymmetric conjoined duplicitas that resulted in a very rare dichotomous spondylosis malformation.

We measured the lengths of some parts of the right and left hemispheres (HEs) in 70 formalin-fixed brains and on 15 computed tomography/magnetic resonance imaging (CT/MRI) images (7 left-handed and 8 right-handed cases) to clarify the morphological changes indicating which HE developed earlier and handedness. In many cases of the fixed brains, 1) the distance from the frontal pole to the occipital pole was longer in the left HE than in the right HE, 2) the distance from the middle plane to the lateral-most portion of the HE was wider in the right HE than in the left HE, 3) the left occipital pole elongated more posteriorly and covered the right occipital pole, and 4) the volume of each HE was nearly the same. The results indicate that the left HE develops and grows slightly earlier in the larger semi-cranium (half of the cranium) than the right HE which develops later in the smaller semi-cranium. The whole brain was more spherical in the female cases than in the male cases. The morphological changes in both HEs for handedness were not evident on the CT/MRI images.

The origin of the posterior scrotal nerve is considered to be the bilateral pudendal nerves but the course to the midline is still obscure. Using 5 late-stage human male fetuses, we identified the single nerve through the intramuscular midline septum of the bulbospongiosus and the bilateral nerves along the left and right sides of the septum. Thus, the posterior scrotal nerve showed a variation: a single midline trunk or bilateral nerves. Branches of the bilateral pudendal nerves ran medially between the muscle and Cowper's gland and, at the midline area, they joined or associated closely. During the proximal course, much or less, the nerve penetrated the superior part of the muscle. The nerve entered the subcutaneous tissue at and near the perineal raphe. The communication with intrapelvic autonomic nerves were suggested behind Cowper's gland. Notably, the midline skin immediately anterior to the anus carried a considerable dense supply of thin sensory nerves. However, these nerves seemed to come from a space between the rectal smooth muscle and the external anal sphincter, not from the posterior scrotal nerve. Therefore, surgical treatment of the intersphincteric layer was likely to injure the original sensory nerve supply to the anterior anal skin.

At birth, the ductus arteriosus (DA) merges with the aortic arch in the caudal side of the origin of the left subclavian artery (ltSCA). Since the SCA (seventh segmental arteries) were fixed on the levels of the seventh cervical-first thoracic vertebral bodies, the confluence of the DA should migrate caudally toward the lower level. We aimed to describe the changing topographical anatomy of the DA and SCA using serial sections. First, we examined serial sagittal sections of 11 embryos (Carnegie stage 15-18), but the specimens were clearly divided into 2 groups with and without the lower confluence of the DA. Next, we examined serial horizontal sections of 40 specimens (Carnegie stage 14-16) and we chose 5 specimens (CRL 11 mm, 3 specimen; 1, 14 mm; 1, 15 mm) including the DA near (within 1-vertebral segment from) the ltSCA. The final approach of the DA occurred during the heart descent in which the apex of the heart migrated from the level of the first to the fourth thoracic vertebral body. Thus, the DA reached the SCA level before establishment of the heart descent. The right aortic arch maintained its entire course in 2 of the 5 specimens. Therefore, the positioning of the DA along the left aortic arch might occur independently of degeneration of the right arch. Notably, the tracheal bifurcation level was higher when the DA-ltSCA distance was greater. A contribution of the increased pulmonary volume was suggested for the final approach of the DA.

The median nerve passes through the humeral and ulnar heads of the pronator teres muscle (PT), although variations such as absence of the ulnar head may exist. We observed histological sections of the upper extremity from 24 embryos and fetuses. In the early stage, the PT extended between the radius and the medial epicondyle of the humerus, but no candidate for the ulnar head was found. In mid-term fetuses, the ulnar margin of the PT was attached to the elbow joint capsule. Moreover, in late-stage fetuses, a small deep part of the PT arose from the thick joint capsule of the humero-ulnar joint near the coronoid process of the ulna. This joint capsule also provided the most proximal origin of the flexor digitorum profundus muscle. Therefore, we considered fetal PT origin from the capsule as a likely candidate for the ulnar head. Consequently, the PT seemed to develop from a single anlage through which the median nerve passed, but later – possibly after birth – a small PT origin from the joint capsule appeared to obtain an aponeurosis connecting the muscle fiber to the ulna. This secondary change in PT morphology might explain the muscle variation seen in adults.