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With enzyme histochemical methods, regional differences were observed regarding the connexions of the tanycyte processes and certain cytoplasmatic of the tanycytes reactions in the ependyma of the infundibular and infra-mammillary recesses of the albino rat. (1) According to the G„PD and TPND methods, the basal processes of the tanycyte ependyma exhibit a definite vascular contact only dorsally from the n. periventricularis arcuatus. Ependymal fibre endings can be seen in the region of the sulcus tuberoinfundibularis and in the inframammillary recess on the basal surface. Medially from the former, the tanycyte processes can be followed into the zona externa of the infundibulum. A convincing tissular connexion with the hypophysis portal system and with the cells of the pars infundibularis adenohypophyseos cannot be observed. (2) The TPPase activity usual in the secretory nervous system structures is missing from the tanycyte ependyma. The ependyma of the caudal end of the inframammillary recess exhibits isolated intense alkaline phosphatase activity. Rostrally from this, in the ependyma of the top of the inframammillary recess, there are more intense enzyme reactions than in the ciliated ependyma elsewhere lining the third ventricle.

The accessory phrenic nerve (APN) is commonly a branch from the nerve to the subclavius. It lies lateral to the phrenic nerve and descends behind, or sometimes in front of, the SV. It joins the main nerve usually near the first rib or sometimes union may even below the root of the lung. The APN may occasionally arise from spinal nerves C4, or C6, or from the ansa cervicalis (10). The incidence of the APN was varies a great deal in the available literature. Felix (Cited by Kikuchi) observed the APN in 17.6 % population he studied (6), in contrast to him Kelly (Cited by Loukas et al.) mentioned the presence of APN in 80.9 % cases (7). The APN may arise as additional roots from one or more of the following nerves: nerve to subclavius; nerve to sternohyoid; second or rarely, sixth cervical spinal nerves; descendens cervicalis; ansa cervicalis; and brachial plexus. It may receive a branch from hypoglossal and may communicate with spinal accessory. The size of the nerve may vary bilaterally (2). The present study was conducted to find out the occurrence of APN in Indian population and discussed its clinical significance. Material and Methods The anatomy of the APN was examined in forty five adult formalin-fixed cadavers (35 male, 10 female; 90 sides) used for gross anatomy dissection at the Kasturba Medical College, Mangalore for undergraduates during 2006 to 2007. The mean age of the cadavers was 58 years (range, 49 to 83 years). The cadavers had been fixed in 10 % formalin solution. None of the specimens revealed any evidence of previous surgical procedures, traumatic lesions, or gross pathologies to the neck and thorax. Findings of the dissec-tion were recorded at different stages of the dissection. The nerves contributing to the phrenic nerve (PN) after it had crossed the scalene anterior muscle (SAM) considered being APNs. When the APN joined the PN above the level of first rib it was considered cervical type and when below the level of first rib it was considered as a thoracic type of APN. Results The PN was found bilaterally in all 45 cadavers (90 PNs) and an APN was present in 48 sides (53.3 %), Summary: The description of accessory phrenic nerve (APN) in the standard textbooks and available literature is vague and sometimes limited to few lines. The incidence of APN varies a great deal from 17.6 % to 80.9 % in the available literature. The aim of the present study was to calculate the incidence and variation of APN in Indian population. Material and methods: Forty five adult formalin-fixed cadavers (35 male, 10 female; 90 sides) used for gross anatomy dissection for undergraduates; during the 2 year period 2006-2007 were considered. Findings were recorded at different stages of the dissection. Results: Out of 90 body sides studied, the APN was present in 48 sides (53.3 %). In 17 of the above sides the APN was confined to the cervical region (Cervical type) and in 31 sides the APN entered the thorax (Thoracic type), all anterior to the subclavian vein (SV). In eleven specimens the APN was found bilaterally. Co...

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