Evidence for the innervation of sperm storage tubules in the oviduct of the turkey (Meleagris gallopavo).

The presence of neural tissue and smooth muscle elements in the vicinity of the oviductal sperm storage tubules at the uterovaginal junction was assessed by several modes of light microscopy. Isolated neurones and small ganglia were identified in the uterovaginal junction of the turkey oviduct. The nerve cell bodies were observed in the tunica mucosa by bright field microscopy. Immunoreactivity against neurofilament antibody and recombinant fragment C of the tetanus toxin reacted with nerve fibres and the nuclei of neurones. Fluorescence microscopy and confocal laser scanning microscopy revealed that nerve fibres continued from the base of the tunica mucosa into the plicae. Axons appeared to terminate on, or run immediately adjacent to, individual sperm storage tubules. Neither phalloidin reacting with F-actin nor the monoclonal antibody against alpha-smooth muscle actin detected smooth muscle fibres in the tissue encapsulating individual sperm storage tubules. In contrast, F-actin was strongly localized in the apical region of the epithelial cells of the sperm storage tubule and in smooth muscle elements in the tunica mucosa and tunica muscularis. These observations present the first evidence for the innervation of the sperm storage tubules. It is suggested that a previously unrecognized neural factor may function in oviductal sperm storage in, and release of spermatozoa from, the sperm storage tubules of hens.

Rete mirabile medullae: vascular specialization of the avian brain stem.

A circumscribed vascular plexus is located between the conjoint proximal ganglion of cranial nerves IX-X and the lateral surface of the avian brain stem. Gross, light, and electron microscopic analyses reveal that this structure is a rete mirabile. This rete is unique in that it resides in the subarachnoid space where it is bathed by cerebrospinal fluid. Microscopic and ultrastructural studies document that the rete is composed of arterioles with wide luminal diameters, marginal folds project from the endothelial cells into the lumen of the blood vessel. The endothelial cells contain numerous pinocytotic vesicles. The underlying basal lamina is penetrated by myoendothelial junctions. One to three layers of smooth muscle cells comprise the tunica media. Bundles of unmyelinated nerve fibers course through the loose connective tissue encompassing the blood vessels.

The parasagittal zonation within the olivocerebellar projection. II. Climbing fiber distribution in the intermediate and hemispheric parts of cat cerebellum.

Olivocerebellar fibers from different subnuclei of the rostral inferior olive decussate in the brain stem and terminate as climbing fibers in one or two narrow, longitudinally arranged zones of the cerebellar cortex. These fibers issue collaterals to the central cerebellar nucleus that receives its afferents from the same cortical zone in which the parent fibers terminate. The rostral medial accessory olive projects to zone C2 and sends collaterals to the posterior interposed nucleus. A differentiation can be made between the rostral pole of this subnucleus which projects primarily to the paraflocculus and the ansiform lobule. More caudal areas connect with zone C2 in the anterior lobe and the paramedian lobule. The dorsomedial cell column projects to a lateral zone (zone A2) of lobule IX and more rostrolateral portions of the medial accessory olive supply a still more lateral zone of this lobule. The rostral half of the dorsal accessory olive sends fibers to zones C1 and C3. These fibers issue collaterals to the anterior interposed nucleus. A distinction can be made between the ventrolateral dorsal accessory olive, projecting to lobules II-IV and the ventral folia of the paramedian lobule and the dorsomedial portion of the rostral dorsal accessory olive that connects with lobules V, VI and the dorsal folia of the paramedian lobule. The most rostral part of the dorsal accessory olive provides more fibers into zone C3, more caudally located cells distribute primarily to zone C1. The rostral principal olive is connected with zone D and collateral terminations are found in the lateral cerebellar nucleus. In the paraflocculus the D zone can be divided into subzones D1 and D2. This study further substantiates the similarity in the organization of corticonuclear and olivocerebellar connections. The results are in general agreement with other recent investigations on the olivocerebellar system (Armstrong et al., '74; Brodal et al., '75; Brodal, '76; Hoddevik et al., '76; Brodal and Walberg, '77a,b; Oscarsson, '73, '76; Oscarsson and Sjölund, '77a,b).

Experimental evidence for climbing fibers in the avian cerebellum.

This study identifies climbing fibers in the cerebellar cortex following brain stem lesions. Antegrade nerve fiber degeneration was studied after electrolytic destruction of rhombencephalic structures in 24 domestic fowl. Direct damage to the cerebellum was precluded by a retropharyngeal surgical approach. Only lesions that include the inferior olivary nucleus were compatible with Fink-Heimer staining of degeneratin nerve fibers in the Purkinje cell and molecular layer. Degenerating axons were identified as climbing fibers from their trajectory in association with Purkinje cell soma and dendrites. Terminal nerve endings were observed only in the basal one-third to one-half of the molecular layer. The presence of climbing fibers in only the contralateral molecular layer was observed in autoradiographic preparation subsequent to unilateral injection of tritiated leucine into the inferior olivary nucleus of three hens. The morphology of the labeled and impregnated degenerating nerve fibers closely coincides with information provided by previous investigators using Golgi stained histological preparations and electron microscopy.

A retropharyngeal approach to the avian brain stem.

The surgical steps used to expose the ventral surface of the chicken's rhombencephalon are detailed. Both acute and chronic experimental preparations can be obtained with this technique. Text material and illustrations provide information on the morphological relationships of the brain stem, skull and other significant structures encountered during the operative procedure.