The whole thigh muscles are covered with the fascia lata, which could have morphological and mechanical features that match the underlying muscles' functions. In this study, we investigated the morphological and elastic properties of the human fascia lata taken from four (anterior, medial, lateral, and posterior) sites on the thigh of 17 legs of 12 cadavers (6 males and 6 females, 75-92 years). The thickness of the fascia lata was determined with a caliper. The interwoven collagen fiber's directions were measured and classified into longitudinal, transverse, and diagonal in two opposing directions, relative to the thigh. Tensile strength test along the longitudinal and transverse directions was performed, and the stiffness, Young's modulus, and hysteresis were determined. Fascia lata at the lateral site (0.8 ± 0.2 mm) was significantly thicker compared to other sites (0.2-0.3 mm). Fiber's directions showed substantial variability among sites, and longitudinally directed fibers were higher in proportion (28-32%) than those in other directions (20-27%) at all sites except for the posterior site. The stiffness and Young's modulus in the longitudinal direction (20-283 N/mm; 71.6-275.9 MPa, highest at the lateral site) were significantly higher than in the transverse direction (3-16 N/mm; 3.2-41.9 MPa, lowest at the lateral site). At the medial site, the proportion of the transversely directed fibers was higher in females than males, with higher stiffness and Young's modulus thereof. The present study shows that the fascia lata possesses site- and gender-dependence of the morphological characteristics and elastic properties.

Early life stress interrupts brain development through the disturbance of various neurotransmitter and neurotrophic factor activities, but the details remain unclear. In the current study, we focused on the serotonergic system, which plays a critical role in brain development, and examined the time-dependent influence of prolonged maternal separation on male Sprague-Dawley rats. The rats were separated from their dams for 3h twice-daily during postnatal days (PDs) 2-20. The influence of prolonged maternal separation was analyzed on PDs 7, 14, 21, and 28 using HPLC to assess concentrations of serotonin and 5-hydroxyindoleacetic acid and using real-time RT-PCR to measure mRNA expression of the serotonin 1A and 2A receptors in various brain regions. HPLC revealed imbalance between serotonin and 5-hydroxyindoleacetic acid in midbrain raphe nuclei, the amygdala, the hippocampus, and the medial prefrontal cortex (mPFC) on PDs 7 and 14. Furthermore, real-time RT-PCR showed attenuation of mRNA expression of the serotonin 1A receptor in the hippocampus and the mPFC and of the serotonin 2A receptor only in the mPFC on PDs 7 and 14. The observed alterations returned to control levels after maternal separation ended. These findings suggest that the early life stress of prolonged maternal separation disturbs the serotonergic system during a crucial period of brain development, which might in part be responsible for emotional abnormalities later in life.

The human triceps surae (two gastrocnemii and soleus) has aponeuroses in the proximal and distal aspects, the latter of which insert into the calcaneus by sharing the common Achilles tendon. These tendinous tissues are known to have elasticity and upon muscle contraction the aponeurosis is stretched both longitudinally (along the muscle’s line of action) and transversely. Higher aponeurosis transverse deformability has been documented, but there is a paucity of information on the morphology and mechanical properties of human aponeurosis. This study aimed to identify morphological and mechanical characteristics of the human triceps surae aponeuroses. Twenty-five triceps surae muscle-tendon units were procured from 13 human donors (formalin fixed, 6 males, 7 females) aged 67–91 years. Specimens of aponeuroses were excised from the eight regions (posterior and anterior regions of the gastrocnemius medialis and lateralis, medial and lateral parts of soleus; proximal, middle, and distal sites each, 2–4 cm × 2–4 cm). Aponeurosis thickness was measured using a digital caliper. Uniaxial tensile tests were implemented to determine the mechanical properties of specimens loaded longitudinally (along the muscle’s line of action) and transversely. The aponeurosis thickness showed significant differences between muscles and sites, while Young’s modulus showed direction-dependent (longitudinal vs. transverse) differences within sites. Results show different morphology and mechanical properties of aponeuroses between synergist muscles. The reason for site-dependent differences in stiffness is due to a reduced aponeurosis thickness rather than a reduction in the material property. The anisotropic elastic feature (differences between longitudinal and transverse directions) of the aponeuroses was more pronounced than previous in vivo findings, suggesting inherent material design of the aponeurosis that matches three-dimensional contractile behavior of muscle fibers.

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