The human platysma contains numerous muscle spindles.

The mimic muscles are usually described as containing no muscle spindles. In the present publication the human platysma was reinvestigated concerning its content of corpuscular sensors. Serial sections through the platysma of seven donors revealed numerous muscle spindles but no Pacini corpuscules. The muscle spindles were located in the cranial two-thirds of the platysma, and were evenly distributed with a tendency to have more spindles in the lateral part of the muscle. Immunohistochemical staining with S46 antibodies revealed a predominance of nuclear bag fibers. The results point to an extended function of the platysma as an afferent center of the lower face mimic muscles.

The architecture of the mouse ciliary processes and their changes during retinal degeneration.

In contrast to most mammalian species, the ciliary processes in the mouse eye form an irregular pattern. Different strains were studied using scanning electron microscopy. The ciliary processes of C57BL/6J animals showed quadrant-specific characteristics: in the superior quadrant, large and radial oriented processes were present. In the inferior quadrant, the processes were small but still mainly radial oriented. In the temporal quadrant, the processes showed a radial, longitudinal course, some being L-shaped. In the nasal quadrant, few processes were oriented longitudinal. In DBA/2 animals, the processes were shorter and the radial orientation less developed. NMRI animals showed the shortest processes with no increase towards the superior quadrant. Additionally we investigated age-related changes in the ciliary processes of Pde6b(rd1) mice, which develop retinal degeneration. In C57BL/6J mice, the ciliary body shape, size and architecture was comparable between 3 and 10 months of age, but showed a mild shortening of the pars plicata in the temporal, inferior and nasal quadrants in animals older than 20 months of age. The parameters of the ciliary body in 3 months old Pde6b(rd1) mice were comparable to those of age-matched C57BL/6J mice. Pde6b(rd1) mice 10 months old revealed significant shortening of the total width of the ciliary body and of the length of ciliary processes in all quadrants. The shape and architecture of the ciliary processes remained preserved.