Cilia are complex organelles involved in sensory perception and fluid or cell movement. They are constructed through a highly conserved process called intraflagellar transport (IFT). Mutations in IFT genes, such as Tg737, result in severe developmental defects and disease. In the case of the Tg737orpk mutants, these pathological alterations include cystic kidney disease, biliary and pancreatic duct abnormalities, skeletal patterning defects, and hydrocephalus. Here, we explore the connection between cilia dysfunction and the development of hydrocephalus by using the Tg737orpk mutants. Our analysis indicates that cilia on cells of the brain ventricles of Tg737orpk mutant mice are severely malformed. On the ependymal cells, these defects lead to disorganized beating and impaired cerebrospinal fluid (CSF) movement. However, the loss of the cilia beat and CSF flow is not the initiating factor, as the pathology is present prior to the development of motile cilia on these cells and CSF flow is not impaired at early stages of the disease. Rather, our results suggest that loss of cilia leads to altered function of the choroid plexus epithelum, as evidenced by elevated intracellular cAMP levels and increased chloride concentration in the CSF. These data suggest that cilia function is necessary for regulating ion transport and CSF production, as well as for CSF flow through the ventricles.

Abstract. Oxytalan connective tissue fibers are a separate and distinct fiber type. Although current histochemical methods cannot distinguish pre‐elastic from oxytalan fibers, the two fiber types are readily distinguished by electron microscopy. Oxytalan fibers are found in periodontal membranes of all teeth of man, monkeys, rats, guinea pigs and mice. Increased numbers and size of oxytalan fibers are observed in periodontal membranes of teeth subjected to increased stress, such as those used for bridge abutments. Edwards (1968) observed increased size and number of oxytalan fibers in periodontal membranes of dog incisors subjected to orthodontic forces. Some oxytalan fibers serve to support the blood and lymphatic vessels leading to the teeth. Oxytalan fibers appear to have a protein component and a stainable component digestible with β‐glucuronidase after peracetic acid digestion. Oxytalan fibers develop in repair tissues of the periodontal membrane. Although oxytalan fibers probably develop in relation to tumors developed from dental tissues, electron microscopy must be employed to distinguish oxytalan from developing elastic tissues inasmuch as histochemical methods are inadequate.

The anatomy of the greater petrosal nerve while within the middle cranial fossa is lacking in the English literature and must be well understood by the surgeon who operates in this area. Twenty-two sides from six female and five male cadavers were examined. Measurements were made between the greater petrosal nerve as it coursed through the middle cranial fossa and surrounding structures such as the arcuate eminence and lateral wall of the middle cranial fossa. Mean distances from the arcuate eminence to the hiatus of the greater petrosal nerve into the middle cranial fossa measured 17.5 mm (SD = 2.2). The length of this nerve within the middle fossa was approximately 10 mm (SD = 2). From the lateral wall of the middle fossa to a midpoint of the greater petrosal nerve mean distances measured 39 mm (SD = 2.4). The mean distance from the foramen spinosum to the exit of this nerve inferior to the trigeminal ganglion measured 7 mm (SD = 1.8). These measurements will hopefully aid the surgeon who wishes to expose or avoid the greater petrosal nerve within the middle cranial fossa.

Electron micrographs of skin from xanthic (gold) sailfin mollies revealed numerous xanthophores, as well as scattered melanophores. The melanophores were seen to contain premelanosomes in various stages of development. This is consistent with the fact that xanthic mollies have been shown to be tyrosinase positive. Melanosomes in xanthic mollies appear to develop by one of two pathways: 1) from an endoplasmic reticulum-derived vesicle which develops an internal lamellar framework, and 2) by fusion of multiple Golgi-derived vesicles which lack an internal lamellar framework. Analysis of the pigments in the skin of the xanthic mollies identified four colorless pteridine pigments (xanthopterin, isoxanthopterin, neopterin, and pterin) and a carotenoid with an absorbance spectrum similar to beta-carotene. It appears that, unlike some other poeciliid fishes, sailfin mollies do not use pteridine pigments for orange coloration. Rather, they appear to rely primarily on carotenoids.

The same oxylalan fibers in pcriodontal membranes of rats wete demonstrated by both light and eleetron mieroseopy. These observations confirm that structures previously identified as oxytalan fibers are, in faet, oxytalan fibets. The structute of oxytalan fibers as revealed by electron microscopy differs from elastic, collagen, and reticular fibers.