Cells Tissues Organs

A correspondence between the appearance of vaginal smears and the layers of the epithelium from which the cells had desquamated was established in untreated rats during the estrous cycle, in control ovariectomized rats and in spayed rats injected with either estrogen or progesterone. The technique for preparing and staining the smears (modified Shorr’s staining procedure) is outlined. A simplified.system of classification which allows the accurate identification of the various stages of the reproductive state in the rat is described. Standing estrus, as well as the influence of estrogen on spayed rats, is characterized by marked cornification of the cells and the disappearance of leukocytes. At the end of estrus, the cornified layer is sloughed off and invasion by leukocytes occurs. During diestrus, as well as in untreated ovariectomized rats, the vaginal contents consistently lack cornified cells whereas leukocytes are very plentiful. Proestrus follows diestrus: the vaginal smear is devoid of leukocytes and characterized by nucleated epithelial cells. Pregnancy, as well as the influence of progesterone on ovariectomized rats, is also characterized by epithelial growth and desquamation but at different rates, resulting in the presence of intermediate cells, and polymorphs and mucus forming a noticeable background to the smear. Since vaginal smears display cell pictures characteristic for each hormone after administration of estrogen or progesterone, exfoliate cytology is a good indicator of the stage of the reproductive state in the rat.

<i>Background:</i> The extracellular matrix (ECM) is a critical determinant of neovessel integrity. <i>Materials and Methods:</i> Thirty-six (polyglycolic acid + polycaprolactone and poly lactic acid) tissue-engineered vascular grafts seeded with syngeneic bone marrow mononuclear cells were implanted as inferior vena cava interposition grafts in C57BL/6 mice. Specimens were characterized using immunohistochemical staining and qPCR for representative ECM components in addition to matrix metalloproteinases (MMPs). Total collagen, elastin, and glycosaminoglycan (GAG) contents were determined. MMP activity was measured using zymography. <i>Results:</i> Collagen production on histology demonstrated an initial increase in type III at 1 week followed by type I production at 2 weeks and type IV at 4 weeks. Gene expression of both type I and type III peaked at 2 weeks, whereas type IV continued to increase over the 4-week period. Histology demonstrated fibrillin-1 deposition at 1 week followed by elastin production at 4 weeks. Elastin gene expression significantly increased at 4 weeks, whereas fibrillin-1 decreased at 4 weeks. GAG demonstrated abundant production at each time point on histology. Gene expression of decorin significantly increased at 4 weeks, whereas versican decreased over time. Biochemical analysis showed that total collagen production was greatest at 2 weeks, and there was a significant increase in elastin and GAG production at 4 weeks. Histological characterization of MMPs showed abundant production of MMP-2 at each time point, while MMP-9 decreased over the 4-week period. Gene expression of MMP-2 significantly increased at 4 weeks, whereas MMP-9 significantly decreased at 4 weeks. <i>Conclusions:</i> ECM production during neovessel formation is characterized by early ECM deposition followed by extensive remodeling.

The zebrafish <i>(Danio rerio)</i> is an alluring model system currently used to study early embryonic development, organogenesis and gene functional analysis. However, few studies have been devoted to post-embryonic development. We have explored the possibility of using this organism to analyze how cranial suture patterning occurs. This study reports on the establishment of the zebrafish skull vault anatomy, calvarial osteogenesis, and cranial suture morphology. Our results demonstrate that the anatomy of the zebrafish cranial vault and cranial sutures is very similar to that of mammalian organisms. Indeed, the zebrafish represents a versatile and valuable model system for the study of the biogenesis of cranial sutures.

Questions on the embryonic origin and developmental significance of the epicardium did not receive much recognition for more than a century. It was generally thought that the epicardium was derived from the outermost layer of the primitive myocardium of the early embryonic heart tube. During the past few years, however, there has been an increasing interest in the development of the epicardium. This was caused by a series of new embryological data. The first data showed that the epicardium did not derive from the primitive myocardium but from a primarily extracardiac primordium, called the proepicardial serosa. Subsequent data then suggested that the proepicardial serosa and the newly formed epicardium provided nearly all cellular elements of the subepicardial and intermyocardial connective tissue, and of the coronary vasculature. Recent data even suggest important modulatory roles of the epicardium and of other proepicardium-derived cells in the differentiation of the embryonic myocardium and cardiac conduction system. The present paper reviews our current knowledge on the origin and embryonic development of the epicardium.

The accumulation of interstitial matrix represents the final common pathway of most forms of kidney disease. Much of this matrix is synthesized by interstitial myofibroblasts, recruited from resident fibroblasts and circulating precursors. In addition, a significant proportion is derived from epithelial-mesenchymal transition (EMT) of tubuloepithelial cells. The importance of EMT has been demonstrated in experimental models, where blockade of EMT attenuates renal fibrosis. Although a number of factors may initiate EMT in the kidney, the most potent is transforming growth factor-β1 (TGF-β1). Moreover, many other prosclerotic factors have effects on EMT indirectly, via induction of TGF-β1. Signaling events in this pathway include activation of Smad/integrin-linked kinase (ILK) and connective tissue growth factor (CTGF). Basement membrane integrity is also a key regulator of EMT. In particular, overexpression of matrix metalloproteinase-2 has a key role in the initiation of EMT, membrane dissolution, and the interstitial transit of transformed mesenchymal cells. Endogenous inhibitors of EMT also play an important counterregulatory role both to prevent EMT and stimulate uncommitted cells to regain their tubular phenotype (mesenchymal-epithelial transition). Such inhibitors represent a potential therapeutic approach, offering a mechanism to slow or even redress established renal fibrosis.

The basis for a higher prevalence of painful temporomandibular disorders (TMD) among women than men is not known. The present study used Fos-like immunoreactivity (Fos-LI) to quantify the pattern and magnitude of neural activation within the trigeminal brainstem complex of male and female rats caused by acute inflammatory injury to the temporomandibular joint (TMJ) region. Also, Fos-LI was assessed in animals given morphine, a preferential mu opioid receptor agonist, or U50,488H, a selective kappa opioid agonist, prior to TMJ injury to determine if opioid modulation of neural activation was similar in males and females. The general pattern of Fos-LI after TMJ injury was similar in males and females. This pattern was characterized by a high density of Fos-positive neurons in the dorsal paratrigeminal nucleus (dPa5), subnucleus interpolaris/caudalis transition region (Vi/Vc-vl), and in the superficial laminae at the subnucleus caudalis/upper cervical spinal cord (Vc/C2) junction ipsilateral to TMJ injury. In contrast to other regions the number of Fos-positive neurons produced at the Vc/C2 junction was proportional to the concentration of mustard oil injected into the TMJ region. In addition, proestrus females produced higher levels of Fos-LI at the Vc/C2 junction than diestrus females or males. Morphine caused a greater dose-related reduction in Fos-LI at the dPa5 and Vc/C2 junction in males than females. By contrast, U50,488H caused a dose-related reduction in Fos-LI only at the Vc/C2 junction of proestrus females. These results support the hypothesis that the Vc/C2 junction region plays a critical role in the integration of pain signals originating from the TMJ region and may underlie sex differences in sensory processing related to TMJ pain.