PMC7453521_01
Macroscopic appearance of the nose of the 1-month-old female Holstein calf. A small, flat nostril (empty arrow) is evident within the region of the muzzle and between the right and left nostrils, which exit at the normal locations. A hair-bearing region (black arrow) is evident near the left edge of the middle nostril
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Fig1
Of the three nostrils, the right and left existed in the normal locations within the nose (Fig. 1).
Dorsal macroscopic view of the nose (a), three-dimensional computed tomography (CT) visualizing the dorsal surface of the nasal bones (b), and dorsal CT (c) and T1-weighted MRI (d) visualizing the nasal cavity in the 1-month-old female Holstein calf. a The bridge of the nose is significantly curved toward the left. The middle nostril (empty arrow) is located in close proximity to the right nostril. b The transformation of the nasal bone allowed a curvature of approximately 30  from the central line of the nasal bone to the left. c The abnormal curve of the nasal septum allowed constriction within the right nasal cavity. The blind end is evident within the middle nostril (empty arrow). Bone-like structures (white arrowheads) are observed within the nasal septum. d A blind-ended middle nostril is evident (empty arrow), although a bone-like structure is not evident. Scale: 25 mm on CT and MRI
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Fig2
On the dorsal view, the bridge of the nose was running straight, with a sudden curve toward the left side (Fig. 2a). T1-weighted [time of repetition (TR), 450; time of echo (TE), 21; slice thickness, 5 mm] and T2-weighted images (TR, 3224; TE, 100; slice thickness, 5 mm) were obtained. Three-dimensional (3D) CT of the skull revealed that the left-sided nasal bone was more curved toward the left side at a third of the apex-caudal length of the nasal bone than the left side within the right-sided nasal bone (Fig. 2b). This transformation of the nasal bone allowed a curvature of approximately 30  from the central line of the nasal bone toward the left side. T1-weighted MRI of the nasal cavity revealed that the nasal septum was abnormally curved along the transformed left-sided nasal bone, with a severe protrusion toward the right nasal cavity within the middle area of the nose (Figs. 2c,d). The abnormal curve of the nasal septum allowed constriction within the right nasal cavity, with a minimum lumen width of approximately 3 mm on CT.
Transverse 3D-CT and T1-weighted MRI corresponding to approximately 1 cm (a and b) and 7 cm (c and d) deeper than the muzzle. a A bone-like structure (empty arrow) is observed in the left inferior site of the middle nostril (asterisk). b An elliptical middle nostril (asterisk) is seen in the space between the right and left nostrils. c The hyperdense vomer (white arrow) leans toward the right, along the transformed nasal septum. d The transformed vomer (white arrow) is imaged as a low-signal-intensity structure. The transformed turbinate bones are also clear. Scale: 10 mm on CT and MRI
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Fig3
Transverse 3D-CT and T1-weighted MRI revealed an elliptical middle nostril within the space between the right and left nostrils, approximately 1 cm deeper than the muzzle (Figs. 3a,b). Transverse 3D-CT and T1-weighted MRI revealed that the nasal septum was thickened, markedly protruding toward the right nasal cavity at approximately 7 cm deeper than the muzzle (Figs. 3c,d).
Endoscopy of the nasal cavities in the left nostril (a), the right nostril (b), the lumen near the opening (c), and the deepest site (d) of the middle nostril. a and b The lumen of the right nostril is narrower compared with that of the left nostril. c The mucosa is smooth and pale pink in the lumen of the middle nostril. d The blind-ended structure (asterisk) is observed approximately 5 cm deeper than the opening of the middle nostril
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Fig4
Endoscopy of the left and right nostrils revealed that the right nostril had a narrower lumen than the left nostril (Figs. 4a,b). In the lumen of the middle nostril, the wall showed a normal mucosal structure with a pale pink and smooth surface (Fig. 4c). The blind-ended structure was observed approximately 5 cm deep toward the opening of the middle nostril (Fig. 4d).
Intraoperative layout during removal of the middle nostril (a and b), and macroscopic layout of the nose soon after surgery (c) and at 1 month after surgery (d). a The muzzle is incised around the entire circumference of the edge of the middle nostril. b The middle nostril is removed (intact) by whole-circumference exfoliation toward the deepest part of the middle nostril. c The incision line on the muzzle is closed by clamping using four cable ties. d The incised line has healed, although irregularities are observed in a dorsoventral direction on the surface of the muzzle (empty arrow)
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Fig5
The muzzle was incised around the entire circumference and along the edge of the middle nostril using an electric scalpel (Fig. 5a). Whole-circumference exfoliation toward the deepest part of the middle nostril allowed intact removal of the middle nostril (Fig. 5b). After closure of the dead space under the surface of the muzzle, four cable ties were passed through small incisions made in both sides near the incision line of the muzzle and clamped to close the incision line (Fig. 5c). The incised line healed; however, irregularities were observed along the dorsoventral direction as a trace of the incised line on the surface of the muzzle (Fig. 5d).
Histology of the middle nostril and hair-bearing surface of the muzzle in the present case (a) and the mucosal surface of the muzzle and nostrils in a normal, age-matched calf (b). a The tissue comprises normal skin structures, including nasal glands and subcutaneous connective tissues (H&E, bar = 250 mum). b Compared with the present case, the glandular lobes are larger in the middle nostril of the age-matched calf (H&E; bar = 100 mum)
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Fig6
Histologically, the surgically removed tissue consisted of normal nostril structures, including nasal glands, skin adnexa, and a few sinus hairs (Fig. 6).