The role of the specific, profilaggrin-containing keratohyalin granules in the developing epidermis of the fetal horse hoof

The adult equine hoof is subdivided into distinct segments with various keratinization modes. In the periople and bulbs of the heel, the epidermis forms a Stratum granulosum with basophilic keratohyalin granules during soft keratinization, whereas in the coronet, wall proper, sole, and frog, the epidermis undergoes hard keratinization by keratinizing and comifying without forming keratohyalin granules. The present study tests the hypothesis that the presence of specific (profilaggrin-containing) keratohyalin granules in the hoof epidermis is correlated with the water-binding capacity and mechanical properties of the hoof horn. To identify these specific profilaggrin-containing keratohyalin granules, tissue samples of fetal hooves were studied with histochemistry, immunohistochemistry, and transmission electron microscopy. In a fetal hoof, a Stratum granulosum is formed in all hoof segments in the wake of the establishment of a segment-specific papillary body, but at differing developmental stages, starting in the coronet, then in the wall proper, and later in the sole and frog, and disappearing again in the same sequence. In the terminal part of the wall proper (i.e., Zona alba), the Stratum granu/osum is retained at least until three days after birth. In the periople and bulbs of the heel, the Stratum granulosum appears last (and is retained in the adult) when the other segments have not yet completely lost theirs. The basophilic granules in the Stratum granulosum are specific profilaggrin-containing granules that were also described in the human skin. These observations are relevant for a better understanding of certain dyskeratotic processes in the hoof epidermis

A study of ultrasound-guided perineural injection of the caudal cervical spinal nerve roots in equine cadavers

OBJECTIVES: To develop an ultrasound-guided cervical perineural injection technique for horses and to evaluate and compare the distribution of contrast agent among perineural, intra-articular and periarticular injections. STUDY DESIGN: Prospective, experimental cadaveric study. ANIMALS: A total of 14 equine cadaveric necks. METHODS: Bilateral ultrasound-guided perineural injection technique for the caudal cervical spinal nerve roots (CSNRs 5-7) was developed. Paramagnetic or iodinated contrast was injected and the distribution of contrast was evaluated using magnetic resonance (MR) or computed tomography (CT) imaging, respectively. The presence of contrast in the CSNR region was determined by an observer unaware of the technique used for each injection performed. The ability of the perineural injection technique to distribute contrast agent to the CSNR region was compared with intra-articular and periarticular injection techniques. RESULTS: Perineural injection delivered contrast agent to the CSNR region 100% of the time and was significantly different when compared with intra-articular injection (p = 0.008). There was no difference in ability to deliver contrast agent to the CSNR region between the perineural and periarticular injection techniques or between the intra-articular and periarticular injection techniques. CONCLUSION AND CLINICAL RELEVANCE: The ultrasound-guided perineural injection technique developed in this study accurately delivered contrast agent to the CSNR region in equine cadavers. This technique could potentially be used for the diagnosis and treatment of cervical pain in horses, particularly in cases where intra-articular cervical articular process joint injections have not been beneficial. Further studies are necessary to assess the effectiveness of the ultrasound-guided perineural injection technique in live horses

The anatomy of the larynx of the bowhead whale, Balaena mysticetus, and its sound-producing functions

This study describes the morphology of the laryngeal apparatus in bowhead whales (Balaena mysticetus) with respect to respiration, deglutition, and vocalization. We also examined the intrinsic cricoarytenothyroid muscle (Musculus (M.) diverticuli laryngei) which forms the laryngeal diverticulum, to ascertain its interactions with the laryngeal cartilages during respiration and sound production. Five fetal larynges and four from adult whales were studied using noninvasive imaging, as well as macroscopic and microscopic techniques. The larynx extends from the skull base into the thoracic inlet. The dorsally curved laryngeal stalk, supported by epiglottis and the corniculate processes of arytenoid cartilages, is situated within the nasopharynx. The epiglottic cartilage exhibits a prominent medial ridge. The arytenoid cartilages are rod-shaped, and extend through the laryngeal cavity. The thyroid cartilage possesses a prominent caudal horn with a fibrous articulation to the ventrally incomplete cricoid cartilage. The M. thyroepiglotticus forms the connection between epiglottic and thyroid cartilages. The M. cricothyroideus lateralis connects the caudal horn of the thyroid cartilage with the cricoid cartilage and the M. cricothyroideus medialis connects the cricoid and thyroid cartilage. An extensive laryngeal diverticulum (Diverticulum laryngis), formed by the laryngeal mucosa and M. diverticuli laryngei, is positioned caudo-ventral to the laryngeal vestibule. The mucosa thickens into a fold medial to the vocal processes of the arytenoid cartilages. Experiments with airflow combined with histological and anatomical evidence strongly suggest a sound producing function for these (vocal) folds. This analysis provides the first account of sound producing structures and function in bowhead whales

Imaging tissue structures: Assessment of absorption and phase-contrast X-ray tomography imaging at 2-nd and 3-rd generation synchrotrons

Several methods have been proposed for imaging biological tissue structures at the near micron scale and with user-control of contrast mechanisms that differentiate among the tissue structures. On the one hand, treatment with high-Z contrast agents (Ba, Cs, I, etc.) by injection or soaking and absorption edge imaging distinguishes soft tissue from cornified or bony tissue. This experiment is most compatible with high-bandpass monochromators (ΔE/E between 0.01 - 0.03), such as recently installed at the LSU synchrotron (CAMD). On the other hand, phase contrast imaging does not require any pre-treatment except preservation in formalin, but places more demands upon the X-ray source. This experiment is more compatible with beam lines, such as 13 BM-D at APS, which operates with a narrow bandpass monochromator (ΔE/E ≈ 10 -4). Here, we compare imaging results of soft, cornified and bony tissues across the 2×2 matrix of absorption edge versus phase contrast, and high versus narrow bandpass monochromators. In addition, we comment on new data acquisition strategies adapted to the fragile character of biological tissues: (a) a 100 % humidity chamber, and (b) a data acquisition strategy, based on the Greek golden ratio, that more quickly leads to image convergence. The latter incurs the minor cost of reprogramming, or relabeling, images with order and angle. Subsequently, tomography data sets can be acquired based on synchrotron performance and sample fragility